Moles {mole, chemistry}| is mass, in grams, divided by molecular weight, in atomic mass units. Substance mass, in grams, is moles multiplied by substance molecular weight, in atomic mass units.
An alchemic substance {philosopher's stone}| can control nature by strengthening essence in each thing.
Physical and chemical tests {chemical test} {property test} can reveal chemicals present.
process
To identify chemical, test the following properties in sequence.
Check color. Check odor.
For state, find solid crystal group, liquid viscosity, or gas nature. Check melting or boiling point.
For solubility, check in water, organic solvent, base, bicarbonate, hydrochloric acid, and sulfuric acid, which protonates O, N, and S.
For combustion, use Beilstein test for halides, ignition test for highly unsaturated or aromatic organic chemicals, and flame test for metals.
process: chemical tests
Use chemical tests for chemical groups.
Sodium iodide in acetone detects halides.
Ferrous hydroxide detects nitro- groups.
Bayer test or bromine in carbon tetrachloride detects double bonds.
Tollen's test detects aldehydes.
Iodoform, dinitrophenylhydrazine, and chromic-acid tests detect aldehydes and ketones.
Sodium bicarbonate, silver nitrate, and neutralization with base, on pH paper or in meter, detect carboxylic acid.
Sodium hydroxide, ferric chloride, and bromine water detect phenols.
Hinsberg test and nitrous acid detect amines.
Acetyl chloride, Lucas test, and chromic acid detect alcohols.
Ferric hydroamate or hydrolysis with base detects esters.
process: spectroscopy
Spectroscopy detects cyano- groups. Infrared spectroscopy detects chemical bonds. Ultraviolet-visible spectroscopy detects aromatic chemical groups. Nuclear magnetic resonance (NMR) detects electron densities. Mass spectroscopy detects elements.
Chemical names {chemical naming} have formats.
name from formula
Chemical name comes from chemical formula. In general, write name for each symbol in formula in same sequence as in formula, in order of increasing electronegativity.
To write correct symbol names, first check formula for complex ions.
Then check for atom or ion valences or charges.
Write first atom or ion name.
If molecule is ionic, and metal ion can have more than one valence number, write metal-ion valence in roman numerals in parentheses.
For covalent molecules, if number of attached oxygens or other atoms is one, write "mono-". If two, write "di-". If three, write "tri-". If four, write "tetra-". If five, write "penta-". If six, write "hexa-".
If molecule is ionic, write second-ion root. If molecule is covalent, write root of atom with attached oxygens or other atoms.
Always add "-ide" to root.
For example, the ionic compound FeCl2 [2 is subscript] is iron (II) chloride. The covalent compound SO2 [2 is subscript] is sulfur dioxide.
Acid names {acid naming} have the following rules. If anion name ends in "-ide", start with "hydro-", add anion root, and then add "-ic acid", as in hydrochloric acid. If anion name ends in "-ate", start with anion root and then add "-ic acid", as in sulfuric acid. If anion name ends in "-ite", start with anion root and then add "-ous acid", as in sulfurous acid.
Polyatomic ion names {complex ion naming} can have five parts.
hydrogen
If ion has one hydrogen, begin name with "hydrogen". For two hydrogens, begin with "dihydrogen". For three hydrogens, begin with "trihydrogen".
oxygen
If ion central atom can attach oxygen in more than two ways, use prefix "per-" for ion with the most oxygen atoms or prefix "hypo-" for ion with the least oxygen atoms.
root
Then use central atom root. Root for C is carbon-. Root for N is nitr-. Root for O is ox-. Root for P is phosph-. Root for S is sulf-. Root for Cl is chlor-. Root for Mn is mangan-.
oxygen suffix
If ion central atom can attach oxygen in at least two ways, add "-ite" to root for ion with fewer oxygens or add "-ate" to root for ion with more oxygens.
ion
Then add the word "ion".
example
ClO4- [4 is subscript and - is superscript] is perchlorate ion, ClO3- [3 is subscript and - is superscript] is chlorate ion, ClO2- [2 is subscript and - is superscript] is chlorite ion, and ClO- [- is superscript] is hypochlorite ion.
CO3-- [3 is subscript and -- is superscript] is carbonate ion.
NO3- [3 is subscript and - is superscript] is nitrate ion and NO2- [2 is subscript and - is superscript] is nitrite ion.
O2-- [2 is subscript and -- is superscript] is peroxide ion.
PO4--- [4 is subscript and --- is superscript] is phosphate ion.
SO3-- [3 is subscript and -- is superscript] is sulfite ion. SO4-- [4 is subscript and -- is superscript] is sulfate ion.
MnO4- [4 is subscript and - is superscript] is permanganate ion.
special
Polyatomic ions can have special names. NH4+ [4 is subscript and + is superscript] is ammonium ion. OH- [- is superscript] is hydroxide ion. CN- [- is superscript] is cyanide ion. C2H3O2- [2 and 3 are subscripts and - is superscript] is acetate ion. HCO3- [3 is subscript and - is superscript] is bicarbonate ion.
Find chemical formulas {chemical formula} {formula, chemistry} using percent composition. For each element, divide percent composition by atomic mass units, to find number of elements per molecular weight. Then divide smallest number into others. If all answers are close to whole numbers, use whole numbers as subscripts in chemical formula. If answers are not all whole numbers, multiply answers by two, then three, then four, and so on, until answers are whole numbers. Then use whole numbers as subscripts in chemical formula.
Chemical formula comes from chemical name {formula from name}. Because molecule has zero total charge, sum of ion charges and atom valences must equal zero. First, write atom or complex-ion symbols in same sequence as in name. Remember or look up ion or atom charges or valence. For atoms or complex ions, assign number subscripts so sum, of charge or valence times subscript, adds to zero.
Ion names follow rules {simple ion naming}. If cation has one atom, use atom name followed by the word ion. For example, Na+ [+ is superscript] is sodium ion. If anion has one atom, use atom root followed by "-ide". For example, O2- [2 is subscript and - is superscript] is oxide ion.
Material properties {material property, chemical} {chemical property} are hardness, strength, color, melting temperature, vaporizing temperature, tensile strength, malleability, ductility, adhesiveness, cohesiveness, and elasticity.
attraction to other substances {adhesiveness}.
attraction to itself {cohesiveness}.
wire-forming ease {ductility}|.
Materials have ability to return to original shape after stretching, compressing, or twisting {elasticity, material}|.
rolling-flat ease {malleability}|.
Substances {element}| can have only one atom type. Hydrogen is H2 [2 is subscript]. Nitrogen is N2 [2 is subscript]. Oxygen is O2 [2 is subscript]. Fluorine is F2 [2 is subscript]. Chlorine is Cl2 [2 is subscript]. Bromine is Br2 [2 is subscript]. Iodine is I2 [2 is subscript].
Elements, such as carbon and sulfur, can have several physical forms {allotrope}|.
Hitting light nuclei with heavy ions {cold fusion, element} makes elements 107, 108, 109, 111, and 112 [discovered from 1980 to 1996].
Lead is stable at 82 protons and 126 neutrons {magic mountain}.
Solid elements {boron} can polymerize, form rings, and be in white borates.
Elements {chlorine} can be gas, be reactive, and make hydrochloric acid. Chlorine makes chlorates, such as bleach, with oxygen.
Elements {fluorine} can be reactive gas that forms strong polar covalent bonds with non-metals and forms ionic bonds to metals.
Elements {hydrogen} can form polar covalent bonds with non-metals, making clear liquid acids. Hydrogen forms hydrides with strongly reducing metals. Hydrogen gas is mild reducing agent and reacts slowly. Chemical reactions involving hydrogen ion and hydride ion are fast.
Elements {nitrogen} can be inert gas. Ammonia is in basic fertilizer. Nitrous oxide is anesthetic. Nitrogen-nitrogen double-bond diazo compounds are solid dyes.
Elements {oxygen} can be gas and be oxidizer but be unreactive at low temperature. Ozone is powerful oxidizer. Two oxygens make the oxidizer peroxide ion. Oxygen combines with hydrogen to make water.
Elements {phosphorus, element} can have atomic number 15, with 15 protons and 15 electrons. Hennig Brand discovered phosphorus [1669]. Phosphorus means "bearer of light" in Greek.
properties
Phosphorus is non-metal, waxy, white or red, and solid. Atomic weight is 30.97, so phosphorus has 16 neutrons. Boiling point is 277 C. Melting point is 44 C. Density at 25 C is 1.82 g/cm^3.
reactions
Phosphorus is reactive and makes phosphates with oxygen. Red phosphorus is not as reactive as white. White is very reactive and catches fire in air at 35 C. At temperatures below 35 C, white phosphorus glows in air. For safety, phosphorus must be in water. Phosphorus is toxic and can damage nose and jaw cartilage and bones.
sources
Heating calcium phosphate with carbon and silicon dioxide produces phosphorus. Yearly amount is several million tons. Phosphorus is also in fluoroapatite, which is calcium, fluorine, and phosphate.
purposes
Phosphorus mainly makes phosphoric acid. Phosphoric acid is for fertilizers, which must have phosphate.
comparison
Phosphorus chemistry is similar to nitrogen chemistry.
Elements {silicon, element} can form silicates with oxygen to make sand, asbestos, mica, glass, and quartz. Etching it makes semiconductor circuits.
Elements {sulfur, element} can make sulfates and sulfites with oxygen, as well as sulfoxides for detergents. Hydrogen-sulfide gas has rotten-egg smell, as does carbon disulfide.
Most elements {metal, element}| are solid at room temperature, melt at high temperature, are gray to white in color, shine if polished, conduct electricity and heat, are malleable, are ductile, are dense, and tend to lose electrons in chemical reactions. The most-metallic elements are in periodic-table lower left. Elemental metals can bind to themselves in pure metals or alloys. They can bind to non-metals to make salts.
Few elements {semimetal} {metalloid}| are soft and crumbly solids or hard and brittle solids, have low melting temperature, are fairly shiny, are gray or colorless, are semiconducting, are not malleable, are not ductile, are rocklike, and have medium density.
Elements {non-metal}| can be colorless gases or colored soft solids, have low melting point, have no shine, have no conductivity, have low density, and tend to gain electrons in chemical reactions. The most-non-metallic elements are in periodic-table top right.
Radium compounds glow in the dark {radioactive element}|. Uranium and plutonium compounds are fuels for nuclear reactors.
Nuclei {transuranium element}| {transuranic element} can be heavier than uranium.
Hitting heavy nuclei with neutrons makes elements 93, 94, 99, and 100 [discovered by 1958].
Hitting heavy nuclei with alpha particles makes elements 95, 96, 97, 98, and 101 [discovered by 1958].
Hitting heavy nuclei with light-element ions, such as boron-5, makes elements 102 to 106 [discovered from 1958 to 1974].
Light-element ions can hit and split nuclei of elements above 106.
Hitting light nuclei with heavy ions {cold fusion, light nucleus} makes elements 107, 108, 109, 111, and 112 [discovered from 1980 to 1996].
Hitting light nuclei with heavy ions, such as calcium-48, makes elements 110 and 113 to 118 [discovered from 1994 on].
stability
At 114 is stable region, in which element lasts longer, especially element with 184 neutrons. Lead is also stable at 82 protons and 126 neutrons, at magic mountain.
Nature has 10,000 different inorganic and 10^11 different organic compounds {molecule}|. People know properties of 10^9 molecules.
color
Metal complexes can have metal ions with d orbitals, which chemically bind other molecules at smaller energy levels than s or p orbitals, lowering energy levels to visible light range, from ultraviolet for s and p orbitals. Iron compounds are red. Cobalt compounds are blue. Nickel compounds are green. Copper compounds are blue or green. Lead compounds are white. Silver compounds are black.
Organic molecules can have conjugated double bonds, which spread electron-orbital energies and lower energy levels to visible-light range, from ultraviolet for single bonds. Organic dyes and indicators have long carbon sequences and have lowest light frequencies, from red to blue.
diameter
Molecules have diameters from 10^-8 centimeters to 10^-5 centimeter. In periodic-table rows, right-most atom is half left-most-atom diameter. Last-row atom diameter is much greater than first-row atom diameter.
electrical property
Atom diameter and proton number determine electrical properties. Diameter changes have more effect than proton-number changes. Noble gases have lowest electron affinity and highest ionization energy, because electron shells are full. Elements in top-right periodic table have highest electron affinity and highest ionization energy, because they have relatively small diameter and relatively large proton number.
Substances {compound, chemistry}| can have different atoms bound together.
In molecules, atom atomic-weight sum is molecule mass {molecular weight}| {formula mass} {molecular mass}, in atomic mass units.
In compounds, element percentage {percent composition} is atomic mass, in atomic mass units, multiplied by number of atoms, divided by molecular weight, in atomic mass units.
High-temperature superconductors {strange metal state} {bad metal} can have impurities.
Ions {complex ion} can have more than one atom. Complex ions typically have central positive atom {mononuclear atom}. Mononuclear atom binds to negative atom ligands. Ligands can chelate to central atom at two or more sites.
properties
Central atom can have high charge, small radius, and filled or half-filled d orbitals. Central atom can have low charge, large radius, and odd number of d-orbital electrons. If central atom has higher positive charge, greater atomic weight, and/or more electrons in d orbitals, complex ion is more stable. d orbitals are most stable when they are half full or have 3, 6, or 8 electrons.
types
Heme has iron as central atom. Chlorophyll has magnesium as central atom. Vitamin B12 has cobalt as central atom.
In covalent compounds, ionization potential is inversely proportional to half the distance {effective atomic radius} between two covalently bound nuclei. Effective atomic radius ranges from 0.037 nanometers to 0.3 nanometers.
In gases, atoms have potential energies, which range from -0.9 eV to +3.6 eV, to attract additional electrons {electron affinity}. Atom electronegativity directly correlates with electron affinity.
Atomic nuclei attract electrons in shared orbitals {electronegativity}. Electronegativity is proportional to sum of ionization potential and electron affinity.
energy
For two bonded atoms, electronegativity difference is proportional to square root of bond-energy ionic bonding part {partial ionic character}, which ranges from 0.8 eV to 4.0 eV.
bonds
If both atoms have high electronegativity, they have covalent bonding. If both atoms have low electronegativity, they have metallic bonding. If one atom has high electronegativity and one atom has low electronegativity, they have ionic bonding.
location
Atom with higher electronegativity has higher probability of containing bonding electrons, and lower probability of containing antibonding electrons, than other atom.
To remove outermost electron, gas atoms require energy {ionization potential} {ionization energy}, which ranges from 4 eV to 24 eV.
Dots can represent electrons in molecule electron structures {Lewis structure}. Atoms, except hydrogen with two dots, have eight dots, to represent electrons in outer shell. Two dots are at atom right, bottom, left, or top. If two atoms bond, two dots are between them. If two atoms have double bond, four dots are between them.
Molecules {radical, molecule}| {free radical} can have no charge but have only one unpaired electron in outer orbital. Peroxides have oxygen free radicals. When peroxide or double-bonded carbon binds to carbon, carbon atom can have free radical.
Two non-metal-atom electrons {unshared pair} can be in non-bonding outer-shell orbital.
Atoms have number {valence, atom}| of outer-shell electrons, or missing outer-shell electrons, needed to complete outer shell.
Atom rotational, vibrational, and translational energy modes have same energy {energy partition} {partition of energy, chemistry}. If energy is different, rotation or vibration gains or loses energy to neighboring rotations and vibrations and returns to equilibrium.
Molecular groups can rotate around single bonds {rotation, bond}. Double bonds, triple bonds, and bonds with resonance have no rotation.
types
Because spherical molecules are symmetric in all three space directions, spherical molecules have no net rotation. Spin around axis leaves molecule the same. Spherical molecules cannot rotate around axis that does not go through center.
Linear molecules can spin around axis perpendicular to chemical bond, so linear molecules can have net rotation. Because linear molecules are symmetric in one space direction, linear molecules have no net rotation around line between nuclei, because spin around that axis leaves molecule the same.
Molecules that are not spherical or linear have no symmetry axis and can rotate around three mutually perpendicular space dimensions.
Molecule bonds can have different vibration types {vibration, molecule}.
types
Vibrations can stretch and compress chemical bonds along line between nuclei. Vibrations can widen and narrow angle between two bonds.
number
Molecules with no bonds cannot vibrate.
Molecules with one bond have one vibration type, bond compressing and stretching.
Molecules with two bonds can have four vibration modes. One bond can stretch, as the other compresses. Both bonds can stretch and compress at same time. Angle between bonds can narrow and widen. One bond can move downward perpendicular to bond plane, while one moves upward perpendicular to bond plane.
symmetry
Molecule symmetries can make two vibration modes indistinguishable and decrease total number of vibration modes.
Compounds {binary compound} {diatomic compound} can have two different elements. Hydrofluoric acid, for glass etching, is HF. The strong acid hydrochloric acid is HCl.
Table salt is NaCl. Sodium fluoride toothpaste compound is NaF. Sodium-bromide stomach soother is NaBr. Sodium iodide iodizing salt is NaI. Potassium chloride salt substitute is KCl.
Poisonous colorless odorless carbon monoxide gas is CO. The poisonous gas nitric oxide is NO. Calcium oxide, lime fertilizer, is CaO. Bronze green color, cupric oxide, is CuO. The solid used in flat stovetops, magnesium oxide, is MgO.
Compounds {triatomic compound} can have three atoms.
Water is H2O [2 is subscript].
Colorless odorless carbon dioxide gas, from burning, is CO2 [2 is subscript].
Inefficient burning makes nitrogen dioxide gas, NO2 [2 is subscript]. The colorless anesthetic gas nitrous oxide is N2O [2 is subscript].
Gas with rotten egg smell, hydrogen sulfide, is H2S [2 is subscript]. The irritating gas for preserving food and for refrigeration, sulfur dioxide, is SO2 [2 is subscript].
Lye or sodium hydroxide strong base is NaOH. The strong base potassium hydroxide is KOH. Milk of magnesia or magnesium hydroxide antacid is MgOH. Slaked lime mortar, calcium hydroxide, is CaOH.
Potash or potassium oxide fertilizer is K2O [2 is subscript].
Calcium chloride drying agent is CaCl2 [2 is subscript], for icy roads.
Black silver tarnish, silver oxide, is Ag2O [2 is subscript].
Hydrogen cyanide poisonous gas is HCN. Silicon-oxide glass is SiO2 [2 is subscript].
Black car-battery-terminal coating, lead oxide, is PbO2 [2 is subscript].
Bleach or sodium hypochlorite is NaClO.
Compounds {polyatomic compound} can have more than three atoms.
organic
Natural gas or methane is CH4 [4 is subscript]. Artificial gas or propane is C3H8 [3 and 8 are subscripts]. Lighter fluid or butane is C4H10 [4 and 10 are subscripts].
Carbon tetrachloride solvent is CCl4 [4 is subscript]. Chloroform anesthetic is CH3Cl [3 is subscript].
The strong base-forming gas ammonia is NH3 [3 is subscript].
Hydrogen peroxide disinfectant is H2O2 [2 is subscript].
iron
Rust or iron oxide is Fe2O3 [2 and 3 are subscripts]. Magnetite iron ore, iron (II) oxide, is FeO. Hematite iron ore, iron (III) oxide, is Fe2O3 [2 and 3 are subscripts].
calcium
Limestone, chalk, and the cement ingredient calcium carbonate is CaCO3 [3 is subscript]. Calcium phosphate bone mineral is Ca3(PO4)2 [3 and 2 are subscripts]. Plaster of paris or calcium sulfate is CaSO4 [4 is subscript].
sodium
Baking soda or sodium bicarbonate is NaHCO3 [3 is subscript]. Soda ash or sodium carbonate is Na2CO3 [2 and 3 are subscripts]. The fixer for photographic solutions, sodium thiosulfate, is NaHSO4 [4 is subscript].
alkali metals
The gunpowder and meat-curing salt saltpeter or potassium nitrate is KNO3 [3 is subscript].
The manic-depressive treatment lithium carbonate is Li2CO3 [2 and 3 are subscripts]. Lithium dialkylamides remove protons in chemical reactions.
Magnesium hydroxide antacid is Mg(OH)2 [2 is subscript]. The laxative, tanning, and dyeing compound Epsom salts or magnesium sulfate is MgSO4 [4 is subscript].
The compound used for GI tract x-rays, barium sulfate, is BaSO4 [4 is subscript].
boron
The compound used in heatproof glass, boron oxide, is B2O3 [2 and 3 are subscripts]. Boron nitride abrasive is BN3 [3 is subscript]. Borax detergent ingredient is B(C2H2O2)3 [2 and 3 are subscripts]. The abrasive carborundum or boron carbide is BC3 [3 is subscript].
aluminum
The treatment for canker sores, and compound for water purification, alum, aluminum potassium sulfate, is AlK(SO4)2 [4 and 2 are subscripts]. The white layer coating aluminum is aluminum oxide, Al2O3 [2 and 3 are subscripts], used in ceramics and abrasives. Aluminum hydroxide antacid is Al(OH)3 [3 is subscript].
copper
The blue compound copper sulfate is CuSO4 [4 is subscript]. The green compound copper chloride is CuCl2 [2 is subscript].
silver
Silver nitrate silver-plating salt is AgNO3 [3 is subscript].
The white layer coating aluminum is aluminum oxide or Al2O3 {alumina} [2 and 3 are subscripts], used in ceramics and abrasives.
Transparent brittle materials {glass}| can have different-length bonds and low thermal expansion. Sand is silicon dioxide. To make glass, melted sand receives small amounts of soda and lime at 2700 F. Melted sand is clear solid but is not crystalline. Glass does not melt at one temperature but becomes more fluid over temperature range. People can cut, blow, shape, and mold hot glass. Drawing molten glass through shaped boats floating in melted glass makes glass sheets. The glass cools slightly and then vertical rollers make it have equal thickness.
Compounds {halide} can contain fluorine, chlorine, bromine, or iodine.
Molecules {metal complex} can have metal ions with d orbitals, which chemically bind other molecules at smaller energy levels than s or p orbitals, lowering energy levels to visible-light range from ultraviolet-light range. Iron compounds are red. Cobalt compounds are blue. Nickel compounds are green. Copper compounds are blue or green. Lead compounds are white. Silver compounds are black.
Nitrogen burns at 800 F to make nitrogen oxides {nitrogen compound}. Cyanuric acid oxidizes nitrogen oxides to carbon dioxide, water, and nitrogen gas.
Ions {phosphate ion}, (PO4)-3 [4 is subscript and -3 is superscript], can have phosphorus and oxygen.
bone
Bone is calcium phosphate, Ca3(PO4)2 [3, 4, and 2 are subscripts]. 20% of skeleton is calcium phosphate. Teeth have calcium phosphate.
energy
Phosphate bonds in adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) store energy.
detergent
Detergents can have phosphates, because phosphate softens water. Many places ban phosphate detergents, because they cause lakes and rivers to have too many algae and other plants, which makes less oxygen in water and kills animal life.
Water {water, molecule} relates to anhydrous, hydrate, efflorescence, deliquescence, hygroscopic, and desiccant.
phases
Water can exist in 13 crystalline phases and five amorphous phases. Water can be high-density amorphous ice at 10 K to 65 K or low-density amorphous ice at 65 K to 125 K. Amorphous ice is in interstellar space. Space amorphous ice can flow with UV light and allows carbon dioxide, carbon monoxide, methanol, and ammonia formation. Cubic ice forms at 135 K to 200 K. Hexagonal ice forms from 200 K to 273 K.
ice surface
Ice has liquid water at surface, several molecules thick, with less structure than solid, because water interacts with air. Ice with impurities has thicker layer. Ice has a liquid surface layer even if it is tens of degrees below freezing. Water-surface-layer charge separation, on ice crystals moving upward and hail falling downward, causes lightning.
Most substances have no adhering water {anhydrous}|.
Solid can absorb water from air and become solution {deliquescence}|.
Chemicals {desiccant}| that can take up water can keep other chemicals dry.
Hydrates can give water to air {efflorescence, water}|.
Substances {hydrate}|, with dissolved ions, can adhere to water.
Compounds can absorb water from air {hygroscopic}|.
Water {hard water}| can have mostly calcium and magnesium ions.
Water {soft water}| can have mostly sodium and potassium ions.
Molecule atoms have stable electrical attractions {bonding, molecule}| {chemical bond}.
electrons
Only outermost electrons participate in chemical bonds, because they can contact another atom.
electrons: stability
Atoms have potential energy. Bonding lowers potential energy. Because radius is less, filled outer-electron shells have lower potential energy than unfilled.
electrons: types
Bonding types result from competition between weak bonds with low activation energy and strong bonds with large activation energy. Single covalent bond overlaps sigma orbitals. Double covalent bond overlaps sigma orbitals and pi orbitals. Triple covalent bond overlaps sigma orbitals and two pi orbitals.
electrons: bond order
Bonding order is 1sigma bonding, 1sigma antibonding, 2sigma bonding, 2sigma antibonding, 2sigma bonding, 2pi bonding, 2pi antibonding, 2sigma antibonding, 3sigma bonding, 3sigma antibonding, 3sigma bonding, 3sigma antibonding, 3pi bonding, 3pi antibonding, and so on.
bond length
Bonded atom pairs always have same average distance between nuclei. Bond length has lowest potential energy.
bond strength
Non-polar covalent bonds are stronger than polar, ionic, or metallic bonds, because atoms share electrons more equally and attractive force between electrons and nuclei is higher, making bond length less. Multiple bonds have shorter bond lengths, because nucleus shielding is more.
Ionic bonds are stronger if ions have more charges and larger sizes.
Metal alloys make stronger metallic bonds, because rapid electron transfer maximizes shell filling.
bond angle
Average angle between two bonds is always the same.
Similar-size non-metals can form covalent bonds {catenation}.
Metals can bind to anion and be soluble {chelation}|. Chelometric titration can measure all metals, except sodium, potassium, and lithium. Disodium EDTA at pH 4 to pH 5 chelates metals. Metal is Lewis acid, and ligand is Lewis base. Eriochrome Black T is indicator and goes from red to blue. Adding magnesium EDTA can measure calcium. EGTA titrates calcium. Xylenol is indicator for acid titrations with EDTA.
Atoms can make numbers {combining capacity} of covalent bonds or can become ions.
Compounds with alternating single and double bonds {conjugation, bond}| have electron resonance.
Molecule electrons can move among connected p orbitals and spread electron orbitals {delocalization}|, which lowers potential energy by minimizing electron repulsions.
Repulsions among electrons in different adjacent orbitals can change orbital shapes {hybridization, bonding}| {hybrid orbital theory}, to make same-shape orbitals. Orbital hybridization can happen if excited states are available.
shape
Hybrid orbitals have ellipsoid shapes. Shape is between s and p orbital shape. Electrons are mostly on one atom side.
types
Four adjacent orbitals make four hybrid orbitals and tetrahedron shape {sp3 hybridization}. Three adjacent orbitals make three hybrid orbitals and triangle shape {sp2 hybridization}, with one unaffected p orbital in pi bond. Two nearby orbitals make two hybrid orbitals and line shape {sp hybridization}, with two unaffected p orbitals in pi bonds.
Atoms or molecules {ligand}| can covalently or ionically bond to central atom, in different configurations depending on orbitals.
number
Central atom can bind coordination number of ligands. Central atom can have six ligands, at octahedron corners {octahedral}, at two d, one s, and three p orbitals. Cubic ligand arrangement has six bonds, at cube corners, at two d, one s, and three p orbitals. Central atom can have four ligands {square planar}, at square corners, at two d, one s, and three p orbitals. Tetrahedral ligand arrangement has four ligands, at tetrahedron corners, at one s and three p orbitals.
central atom
Metal ions have five d orbitals. z^2 and x^2 - y^2 orbitals point along axes and have higher energy. Electrostatic repulsion causes xy, yz, and xz orbitals to point between axes and have lower energy. If field is weak, energy difference is small, and all electrons go to all five d orbitals, with parallel spins, as in Hund's rule. If field is strong, metal d-orbital energy differences are large, spins pair, and electrons stay in the three lower-energy d orbitals.
Minimum potential energy is when molecule atoms, except hydrogen, have eight electrons, in four orbitals, in outer shell {octet rule}.
Hybrid bonding orbitals can represent alternative electron-arrangement averages, such as single and double bond interchanges {resonance, bonding}|.
delocalization
Molecule electron orbitals spread when electrons move between connected p orbitals, lowering potential energy by minimizing electron repulsions.
aromatic compounds
Benzene and other aromatic compounds, which have five-member or six-member carbon and nitrogen rings with alternating single and double bonds, have electron resonance.
conjugation
Compounds with alternating single and double bonds have electron resonance.
carboxyl group
If an atom single-bonds to an atom type and double-bonds to same atom type, so bonds can interchange, as in carboxyl ion -COO- or guanidium ion -CNN-, compound has electron resonance.
Electrons between two atomic nuclei reduce electric repulsion {shielding}|, by reducing nucleus apparent positive charge.
Weak electrical attractions {van der Waals force} are between charges induced on neighboring molecules by electronegative atoms. Van der Waals forces are at distances less than 0.25 nanometers. Higher-atomic-weight atoms make stronger van der Waals forces.
Bonding theories {molecular orbital theory} (MO) can use molecular electron orbitals. Bonding orbitals have electrons between nuclei, which causes shielding. Antibonding orbitals have electrons beyond nuclei, with no shielding. Only these two wave-interference types result in net amplitude and so are the only bonding types.
number
Number of occupied bonding orbitals compared to number of occupied antibonding orbitals gives total bond number. If antibonding equals bonding, no bond forms.
strength
Bond strength depends on atomic-orbital overlap, which is greatest for identical orbitals. If electronegativity difference between atoms is great, bonding and antibonding orbitals are similar in energy, because shielding is minimal.
errors
Molecular orbital theory weights ionic effects too heavily.
Bonding theory {valence-bond theory} involves electric interactions between atoms. Molecular orbitals only form between valence electrons, because only valence electrons can contact outside world and valence electrons are least bound. Other electrons are too tightly bound. However, valence-bond theory weights ionic effects too lightly.
Enough energy {bond energy} {energy, bond} can break bonds. Bond breaks at 40,000 to 260,000 calories per mole. Because shell is full, atoms in chemical bonds have lower energy and are more stable than isolated atoms. Symmetries in covalent chemical bonds make energy lower by minimizing electron repulsions.
Electrons can induce electric dipoles and cause electrical attractions {London energy} between atoms. London energy is at distance less than 0.6 nanometers.
Atoms {ion}| can donate electrons to or accept electrons from other atoms, so atom becomes positive or negative.
Atoms with strong electric forces can gain several electrons to fill shell {anion}|.
Atoms with strong electric forces can lose several electrons to make empty shell {cation}|.
One covalent sigma bond {single bond}| can be between two atomic nuclei.
One sigma and one pi bond {double bond}| can be between two atomic nuclei.
One sigma and two pi bonds {triple bond}| can be between two atomic nuclei.
Molecular orbitals {antibonding orbital} can be difference between two atomic orbitals that have quantum-wave destructive interference. Antibonding orbitals have electrons beyond nuclei. No shielding makes positively charged nuclei repel. Outside electrons pull positively charged nuclei apart.
Molecular orbitals {bonding orbital} can be sums of atomic orbitals that have quantum-wave constructive interference. Bonding orbitals have electrons between nuclei. Shielding reduces repulsion of positively charged nuclei. Between electrons pull positively charged nuclei together.
Most atomic and molecular orbitals {non-bonding orbital} have no sharing, overlap, or quantum-wave interference.
Chemically bonded hydrogen atom near chemically bonded nitrogen, oxygen, or fluorine atom forms electric dipole {hydrogen bond}|. Nitrogen, oxygen, or fluorine unshared-electron pairs attract hydrogen nuclei. Only nitrogen, oxygen, and fluorine atoms are small enough for unshared-electron pairs to get close enough to hydrogen nucleus.
strength
Electric attraction is one-tenth covalent-bond strength.
time
Hydrogen bonds break and reform in 10^-11 seconds.
forms
Hydrogen bonds can have two configurations. Oxygen atom, hydrogen atom, and atom bonded to hydrogen can be in straight line. This hydrogen-bond type is stronger. Water has many strong-type hydrogen bonds.
At hydrogen, angle of nitrogen, oxygen, or fluorine atom and atom bonded to hydrogen angle can be 109 degrees, as in tetrahedral configuration. This hydrogen-bond type is weaker.
multiplication
Hydrogen bond polarizes atom bonded to hydrogen atom. Polarization aligns other atoms and causes more hydrogen bonding.
Atoms can donate electrons to or accept electrons from other atoms, so one atom becomes positively charged and other atom becomes negatively charged, and opposite ion charges attract {ionic bonding}|. Anions with strong electric forces can gain electrons to fill shell. Cations with strong electric forces can lose electrons to empty shell.
Metal atoms exchange outer electrons to try to fill outer shell {metallic bonding}|. Mercury is liquid, because it has weak metallic bonds.
Two atoms can share two electrons {covalent bond}|, which spend most time between the atomic nuclei and share a bonding orbital. Molecular electron orbitals fill with electrons using same rules as for filling atomic electron orbitals. Bonding orbitals fill before antibonding orbitals. Covalent bonding fills both atoms' outer shells.
antibonding
Shared electrons can spend most time outside the atomic nuclei on line between nuclei, in antibonding orbitals. Outside electrons pull nuclei apart and so oppose covalent chemical bonding. Net bond number equals (bonding electrons - antibonding electrons) / 2.
factor
Atoms with weak electric forces make covalent bonds. Atoms with weak electric forces can gain electrons to complete shell. Atoms with weak electric forces can lose electrons to empty shell.
Two different-electronegativity atoms can bind by sharing electrons, and one atom attracts shared electrons more {polar bond}| {polar covalent bonding}.
Covalent chemical bonds {sigma bond}| {sigma bonding orbital} can overlap atom s orbital and other-atom 1s or 2s orbital, 1p or 2p orbital, or s-p hybrid orbital, with constructive interference and electrons between nuclei. Sigma bonding orbitals are symmetric around line joining the atomic nuclei. Atom s orbital can overlap other-atom 1s or 2s orbital, 1p or 2p orbital, or s-p hybrid orbital {sigma antibonding orbital}, with destructive interference and electrons not between nuclei.
Covalent chemical bonds {pi bond}| {pi bonding orbital} can overlap atom 2p orbitals, so shared electrons are between nuclei but in two regions, one above and one below line between atomic nuclei. Atom 2p orbital can overlap other-atom 2p orbital {pi antibonding orbital}, with destructive interference and electrons not between nuclei.
Molecule atoms can make and break chemical bonds {chemical reaction, inorganic}|. Chemical reactions make reactant molecules into product molecules. Chemical reactions typically release energy as heat.
energy release
Molecules have energy levels, with Boltzmann energy distribution. Reactants have higher ground-state potential energy and/or more widely spaced energy levels. If there is reaction path, molecules tend to become products, which have lower ground-state potential energy and/or less widely spaced energy levels. Potential-energy difference becomes kinetic energy and so heat. Products and heat have higher entropy than reactants.
reaction rate
Chemical-reaction rate depends on activation energy to go from reactants to products. Reaction rate depends on forward and backward chemical-reaction rates.
mass
Balanced chemical equations allow knowing reactant or product amounts from reactant or product amounts. Ratio between unknown reactant or product coefficient and known reactant or product coefficient equals ratio between unknown reactant or product moles and known reactant or product moles.
Reaction diagrams {Börn-Haber cycle} can show how molecule chemical properties relate to atomic chemical-property combinations.
Reaching chemical-reaction transition state requires energy {activation energy}| (Ea). Transition state has potential energy that is higher than reactant potential energy and is higher than product potential energy. For drugs, activation energy equals site-atom attached-hydrogen effective activation-energy sum.
Chemicals {catalyst}| can increase reaction rate, but chemical reaction does not alter them.
amount
Reaction needs only small catalyst amount, because reaction reuses catalyst. However, catalysts can break down, have dirt or product coatings, or have surface damage.
processes
Catalysts reduce energy needed to start reaction. Catalysts allow transition state with lower activation energy, make molecule easier to attack, allow leaving group to leave easier, make attacking group attack better, orient molecules for optimum bond stretching, provide functional groups for forces or transfer, or line up reactant molecules.
types
Enzymes are protein catalysts.
Acids and bases are catalysts {homogeneous catalyst}. Basic catalysts cause isomerization, halogenation, or condensation. Acid catalysts cause tautomerism, solvolysis, or inversion. Neutral catalysts polarize solvent.
types: solid
Solid catalysts {heterogeneous catalyst} provide structured surfaces. Ceramic or metal catalysts are for industrial processes. Surface chemistry is for catalysis, corrosion, membranes, surface tension, and electrodes.
If molecule collision energy with surface is same as surface thermal-vibration energy, surface can absorb molecule and collision energy. Molecule-absorption rate depends on collision energy. Electrode surfaces have an ion layer, covered by an opposite-charge ion layer.
Catalytic surfaces must not bind too strongly or too weakly. Collision rate is not important, because absorption surface is large. Activation energy is small and not determining factor for surface catalysts.
As atoms bind to catalyst, catalyst surfaces orient molecules and dissociate molecular bonds. Then new bond can form by collision or reorientation. Molecules on catalysts can move depending on impurities, defects, and crystal planes. Movement allows reaction atom transfer.
types: gas and metals
Gas molecules chemisorb on metals, because metal absorption area is much greater than gas collision area, so entropy decreases. How saturated surface is affects absorption. If concentration is high or time on surface is long, absorption is less. Because neighboring sites move, they affect absorption sites.
Metals bind oxygen strongest, then acetylene, ethylene, carbon monoxide, hydrogen, carbon dioxide, and nitrogen. Platinum, iron, vanadium, and chromium can adsorb all these substances. Manganese and copper can adsorb some. Magnesium and lithium only absorb oxygen. Iron, nickel, platinum, and silver surfaces are catalysts for hydrogenations and dehydrogenations.
Nickel oxide, zinc oxide, and magnesium oxide are catalysts for oxidations and dehydrogenations, because they are semiconducting. Metal sulfides are catalysts for desulfurations, because they are semiconducting. Aluminum oxide, silicon oxide, and magnesium oxide are catalysts for dehydrations, because they are insulators. Phosphoric acid and sulfuric acid are catalysts for polymerizations, isomerizations, alkylations, and dealkylations {cracking, petroleum}.
Chemical reaction starts when outside energy stretches, twists, or compresses molecule chemical bonds {initiation, reaction}.
energy
Energy typically comes from heat or light. Light adds electric energy and affects electrons directly. Heat makes molecules move faster with more kinetic energy, causing more and higher-energy molecule collisions.
size
In large molecules, collision is less likely to disrupt bond, because collision is more likely to hit other bonds.
shape
Molecule shape determines if collision affects bond. If collision is along bond line, bond disruption is more than if collision is from side.
charge
Bond disruption is greater if colliding atoms have opposite electric charges. Bond disruption is greater if colliding atoms have same electric-charge absolute value.
Light can cause chemical reaction {photoactivation}, as in photosynthesis.
Chemical bond is stable state with relatively low potential energy. See Figure 1. Collision, heat, or radiation can stretch, twist, or compress chemical bond to maximum extent {transition state}| {activated complex}, as molecule electrical attractions resist chemical-bond disruption. Transition state has greatest disruption, highest potential energy, and maximum separation. See Figure 2. If it can become new conformation or molecule, transition state is hybrid of stable chemical states before and after chemical reaction.
From transition state, molecules can go back to original states or become new conformations or molecules, with equal probability. See Figure 3.
After displacement from equilibrium, system returns to equilibrium and sum of all work done by forces during displacement and return equals zero {principle of virtual work} {virtual work principle}.
Chemical reactions proceed over time {reaction rate}|.
rate
Reaction goes in two directions at once, from reactants to products {forward reaction} and products to reactants {reverse reaction}. Backward reaction rate divides into forward reaction rate to find overall rate.
half-life
Reactant amount eventually reaches half original amount {half-life, reactant}: half-life = C * (1 / c^(n - 1)), where C is constant, c is concentration, and n is reaction order.
factors
Reaction rate depends on temperature, pressure, reactant concentrations, catalysts, states, and reactant physical forms: rate constant = (collision frequency) * e^(-E / (R*T)), where R is gas constant, T is temperature, and E is activation energy. If reactant concentration is in excess, concentration stays constant during reaction.
process
Reactants and products have initial, intermediate, and final concentrations. Reactions destroy reactants and makes products.
process: mechanism
Reaction rate depends on reaction mechanism. Reaction mechanism can depend on zeroth, first, second, or third reactant-concentration power {order, reaction}.
Reaction rate can be constant {zero-order reaction}.
Reaction rate can depend on one reactant concentration or pressure {first-order reaction}. First-order reaction uses linear equation: rate = dC / dt = k * C0 where dC is concentration change, dt is time change, k is rate constant, and C0 is concentration. ln(C / C0) = -k*t, where C is concentration, C0 is initial concentration, k is rate constant, and t is time. Find final and intermediate product or reactant concentrations from initial concentration, rate constant, and time: Cf = Ci * e^(k*t), where Cf is final concentration, Ci is initial concentration, k is rate constant, and t is time.
Reaction rate can depend on two reactant concentrations or pressures {second-order reaction}. Second-order reaction uses quadratic equation.
process: temperature
Reaction rate depends directly on temperature. Reaction rate is faster with higher temperature. 10-K increase doubles reaction rate.
process: form
Reactant physical form affects reaction rate. Greater surface area, lower viscosity, and higher solvent polarity increase reaction rate. If surfaces must touch for reaction, rate depends on contact area.
process: state
Reactant gas, liquid, or solid physical state affects reaction rate.
process: rate constant
Physical factors that affect reaction rate are temperature, catalyst, physical form, and physical state. All physical factors are in one constant {rate constant}. People know rate constants for many chemical reactions.
process: rate-limiting
In chemical-reaction series, in which previous-reaction products are next-reaction reactants, one reaction {rate-limiting reaction} is slowest.
process: ions
Ionic reactions are fast if both reactants have opposite charge. Large ions and high-charge ions increase reaction rate. Increased ionic strength increases rate, if ions have opposite charge, but otherwise slows reaction rate. Solvents with high dielectric constants, like water, reduce repulsions and attractions between reactants and slow reaction rates.
Acid-base reactions are ionic, and reaction rate increases with more acid or base. Ions can modify reaction by forming weak acids and bases.
In ionic solutions, higher ionic strength, more polar solvent, and greater ion charge causes high collision rate and short contact time, so reaction rate is higher.
process: non-polar
In non-polar solutions, higher viscosity makes contact longer and collision rate lower, so reaction rate is lower.
Chemical-reaction equation {chemical equation} uses molecule chemical formulas and special symbols. Reactant formulas are on left, and product formulas are on right.
direction
Horizontal arrow pointing right separates reactants from products. Delta symbol means to add heat. hv symbol means to add light.
terms
Plus signs separate molecules.
symbols
Up arrow (^) at formula right indicates that reaction produces gas. Down arrow at formula right indicates that reaction precipitates solid. The letter s at formula right means that reagent is solid. The letter l at formula right means that reagent is liquid. The letter g at formula right means that reagent is gas. The letters aq at formula right mean that reagent is aqueous.
balance
Atoms on chemical-reaction left must also be on right, so both sides have same atom numbers and types {conservation of mass, chemical equation}.
Before chemical reaction, chemicals {reactant}| {reagent} exist.
If chemical reaction has more than one reactant, one reactant {limiting reagent}| depletes first as reaction proceeds. Find limiting reagent from balanced chemical reaction, using the following rule. If first-reactant coefficient to second-reactant coefficient ratio is larger than first-reactant moles to second-reactant moles ratio, second reactant is limiting reagent.
After chemical reaction, new chemicals {product, reaction}| exist.
Relative reactant and product masses have relations {stoichiometry}|.
If written chemical reaction has one product or reactant missing, calculations {balancing chemical equation} can find missing product or reactant. If written chemical reaction has one coefficient missing, calculations can find missing coefficient.
First, find all missing atoms, because each atom on left must also be on right.
Using found atoms, write positively charged atom symbol first and negatively charged atom symbol second.
Use naming-formula rules to find candidate molecule, using number subscripts for symbols if necessary.
Write equation using candidate molecule.
Add coefficients to reactants and products to make atom numbers equal on both sides. To find coefficients, first balance metal-atom coefficients, then balance non-metal-atom coefficients, except H and O, then balance hydrogen coefficients, and finally balance oxygen coefficients. If chemical equation is not yet balanced, double metal-atom coefficients, then balance non-metal-atom coefficients, except H and O, then balance hydrogen coefficients, and finally balance oxygen coefficients.
In chemical reactions, total mass {conservation of mass, reaction}, total charge {conservation of charge}, and total energy {conservation of energy, reaction} stay constant. Sum of reactant charges equals sum of product charges. Total reactant mass equals total product mass. Reactant energy equals product energy plus heat.
In chemical reactions, formed or used gas volumes relate by whole-number ratios {combining volumes law} {law of combining volumes} {Guy-Lussac law} {law of Guy-Lussac}.
In reaction series, in which previous-reaction products are next-reaction reactants, total change over series equals sum of reaction changes {Hess' law} {Hess law}.
Chemical-reaction product amount {yield, reaction}| never equals maximum theoretical product amount, because reactions are inefficient. Calculating reaction efficiency {percent yield} uses the balanced chemical reaction. Percent yield equals ratio between product moles and limiting-reagent moles, expressed as percentage.
Knowing chemical equation and reactant and product concentrations at equilibrium allows reaction-constant calculation {equilibrium constant}|. Equilibrium constant is product of product concentrations, each raised to power of its chemical-equation coefficient, divided by product of reactant concentrations, each raised to power of its chemical-equation coefficient. For example, in chemical equation 2 A + 3 B -> C + 4 D, equilibrium constant K = ([A]^2 * [B]^3) / ([C] * [D]^4). Chemical reaction aX + bY -> cZ + dW equilibrium constant is K = (X^a * Y^b) / (Z^c * W^d).
tables
People know many reaction equilibrium constants, at specific temperatures. Dissociating acids and bases have equilibrium dissociation constants. Dissolving salt in water or other solvent has equilibrium solubility constant.
irreversible
Equilibrium constant greater than 10^9 means reaction is irreversible.
product concentrations
Equilibrium constant and initial reactant concentrations result in product concentration at equilibrium. First, use chemical equation to make equilibrium-constant equation with correct exponents. In equilibrium-constant equation, replace product concentration with x if coefficient is 1, replace with 2*x if coefficient is 2, replace with 3*x if coefficient is 3, and so on. If coefficient is 1, replace reactant concentration with its initial concentration minus x. Replace with 2 * (initial concentration minus x) if coefficient is 2. Replace with 3 * (initial concentration minus x) if coefficient is 3, and so on. For example, for chemical equation 2 A + 3 B -> C + 4 D, equilibrium constant K = ([A]^2 * [B]^3) / ([C] * [D]^4). To find A concentration: K = ((2*x)^2 * B^3) / (C * D^4). Use equilibrium constant value from table of constants. Solve for x.
Product concentration is x times its coefficient in chemical equation. Reactant concentration is (initial concentration minus x) times its coefficient in chemical equation.
partition functions
Reactant and product partition functions can find chemical-reaction equilibrium constant.
After reaction, reactant and product amounts stay constant {equilibrium, reaction}|. At equilibrium, total-energy change is zero, free-energy change is zero, substance change is zero, all chemical potentials are equal, and all forces are equal. Product concentrations and reactant concentrations have equilibrium-constant ratio.
rates
At equilibrium, forward and backward reaction rates are equal. Product-formation rate equals reactant-formation rate. Amounts do not change, so reaction is complete.
factors
Equilibrium concentrations and amounts do not depend on catalyst or factors affecting reaction rate. Equilibrium concentrations depend only on energies and entropies.
factors: temperature
If reaction requires heat, temperature increase makes more product.
factors: pressure
If gas is reactant, pressure increase makes more product. If temperature increases, system acts to reduce pressure and so return to equilibrium.
factors: amount
Adding more reactants changes them to products, until equilibrium reestablishes. Adding more products turns them into reactants, until equilibrium reestablishes. Increasing reactant concentration, or removing product, increases product.
Substances have chemical reactivity {activity, chemical} {chemical activity}| {chemical potential, reactivity}. Chemical activity expresses true concentration or pressure. Substance concentration relative to other concentrations depends on chemical potential. Solids and pure liquids, including water, have chemical activity one. Metal activities, in decreasing order, are Li, K, Ba, Sr, Ca, Na, Mg, Al, Mn, Zn, Cr, Fe, Cd, Co, Ni, Sn, Pb, H, Cu, Ag, Pd, Hg, Pt, and Au. Non-metal activities, in decreasing order, are F, Cl, Br, and I.
Chemical potential difference {affinity, reaction}| from reactants to products is chemical-reaction driving force.
Substance partial pressure {fugacity}|, relative to other partial pressures, depends on chemical potential.
Methods can control reaction {reaction control}. In non-polar solution, if activation energy is low, diffusion controls reaction. In ionic solutions, if activation energy is high and is late in reaction, use vibration at frequency similar to rotation frequencies to control reaction, because bonds are short. In ionic solutions, if activation energy is high and is early in reaction, use translational energy to control reaction, because bonds are long.
Lasers can initiate photolytic reactions {flash photolysis}.
Mixing chambers and controlled reactant flows control reaction {flow technique}.
Molecule streams {molecular beam} can hit other molecules at precise speeds and orientations.
Temperature can change equilibrium {relaxation method, chemistry}, if reaction requires heat.
Reactions have different forms {reaction types}: chain, synthesis, decomposition, substitution, metathesis, nucleophilic, electrophilic, and molecular rearrangement.
Phosphoric acid and sulfuric acid are catalysts for carbon-chain dealkylations {cracking, dealkylation}| {dealkylation}. Petroleum separation uses phosphoric acid, sulfuric acid, silicon oxide, and aluminum oxide. Silicon oxide and aluminum oxide build branched hydrocarbons. Olefins form on platinum with silicon oxide, followed by isomerization, ring formation, splitting, and hydrogenation.
Two chemicals can bind to make something with different properties than original chemicals {hypergolic}. For example, hydrazine and nitrogen tetroxide react when in contact to make nitrous oxide and water: N2H2 + NO4 -> 3 NO + H2O [where 2 and 4 are subscripts].
Pressure can cause luminescence {triboluminescence}.
Product can be reactant, which can make more product {chain reaction, chemistry}|. Reaction rate continually increases, until system physically disrupts.
One reactant can make two products {decomposition reaction}. Decomposition includes hydrolysis and dehydration reactions.
Chemical can attack negatively charged group {electrophilic reaction}.
Two compounds can make two new compounds {double replacement reaction} {metathesis reaction}. Acid-base reactions have metathesis. Metal compounds can catalyze carbon-carbon double-bond changes.
One reactant can change to same chemical in different configuration {molecular rearrangement}.
Chemical can attack positively charged group {nucleophilic reaction}.
Element and compound can make another element and another compound {single replacement reaction} {substitution reaction, inorganic}. Metal-atom to metal-ion oxidation has substitution.
Two reactants can make one product {synthesis reaction}. Synthesis includes polymerization, hydration, and oxidation reactions, like rusting and combustion.
Energy transfer can involve permanent change that cannot reverse {irreversible reaction}, because heat is made.
Energy transfer can have no friction or other opposing changes {reversible reaction}. In reversible reactions, external and internal temperatures and pressures are approximately the same. In reversible processes, system and surroundings are always in equilibrium. Reversible processes approximate slow energy transfer with small force and minimal resistance.
In reactions {spontaneous reaction}, activation energy can be less than difference in potential energy between transition state and products.
Chemical reactions can release or absorb thermal energy {heat of reaction}|.
Chemical reactions {endothermic reaction} absorb energy if product potential energy is higher than reactant potential energy. Endothermic reactions make complex molecules and require high temperature or strong light at specific frequency.
Chemical reactions {exothermic reaction} release energy {heat, reaction} if reactant potential energy is higher than product potential energy.
Reactions {monomolecular reaction} can have one reactant, as in SN1 and E1 reactions. Molecule vibrations and rotations can cause molecule to decay to new state, as in gas decays, Type I nucleophilic substitutions, Type I eliminations, dissolution, and state changes.
Reactions {bimolecular reaction} can have two reactants, as in SN2 and E2 reactions. Molecule collisions can form transition states and can transfer energy or functional groups, as in isomerizations, Type II nucleophilic substitutions, Type II eliminations, enzyme reactions, syntheses, and dimerizations.
Reactions {termolecular reaction} can have three reactants, as in enzymatic reactions.
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Date Modified: 2022.0225