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Chemistry – Quick Reference Sheet

Physical Properties of Matter

Measurement and Calculations

States of Matter
Solid: molecules are grouped tightly; volume and shape are fixed
Liquid: molecules are grouped loosely; volume is fixed; shape varies
Gas: molecules are free; volume and shape varies
Extensive Properties (Size-Dependent Properties)
Mass (m): measurement of the amount of matter in an object
Moles (mol): 6.022*1023 particles of a given substance is one mole
Solubility: the maximum amount of a substance (solute) that dissolves in a given quantity of solvent to produce a saturated solution
– Saturated Solution: a solution containing the maximum amount of solute dissolved in a given amount of solvent
– Unsaturated Solution: a solution containing less solute than a saturated solution; any solute added to the solution would dissolve until it becomes saturated
– Supersaturated Solution: a solution containing more solute than is possible
Volume (V): Measurement of space an object occupies
Intense Properties (Size-Independent, Identity-Dependent)
Boiling Point (bp): the vapor pressure of a liquid is equal to the external pressure on the liquid; phase shift from liquid to gas
Color
Conductivity: measurement of heat or electrical transmission
Density (D): mass per volume; D=m/V
Melting Point (mp): substance phase shifts from solid to liquid at this temperature; point at which crystalline bonds are broken
pH: the negative log of the hydrogen-ion concentration of a solution; pH of acids 0-7; pH of bases 7-14; pH = 7.0, neutral
Temperature (T): average kinetic energy of matter particles; heat transfer direction is determined by temperature

Conservation of Mass: mass is neither created or destroyed
Conservation of Energy: energy is neither created or destroyed
Dimensional Analysis: uses equivalent values to convert one unit of measurement to another.

Significant Digits:

Non-Zero-Digits — Significant
In-between Zeros (zeros between other sig. digits) –Significant
Leading Zeros (zeros to the left of other sig. digits) — Not significant
Final Zeros (zeros to the right of other digits):

After the decimal — Significant
Before the decimal — if no decimal is shown — Not significant;

If a decimal is shown — Significant

Specific Heat: the amount of heat required to raise the temperature of one gram of a substance by 1° Celsius
Mole(mol): 6.022*1023 (Avogadro’s number) particles of a given substance is one mole; each mass number (in grams) is equivalent to one mole of that element
Molar Mass: Find the mass for each element in the molecule—multiply the number of atoms in the molecule by the atomic mass number; then add the total mass for each element in the molecule.

$\mathbf{2MnO_4}$
$2\mathrm{Mn} = 2 \cdot 54.94\mathrm{g}=109.88\mathrm{g}$
$2\mathrm{O}_4 = 8 \cdot 16.00 \mathrm{g}=128.00\mathrm{g}$
$1\mathrm{mol} \quad2\mathrm{MnO}_4 = 237.88\mathrm{g}$

Temperature Conversions
$^{\circ}\mathrm{F}=(^{\circ} \mathrm{C} \times \frac{9}{5})+32^{\circ}$ $^{\circ}\mathrm{C}=\frac{5}{9}(^{\circ}\mathrm{F}-32^{\circ})$
$^{\circ}\mathrm{C}=\mathrm{K}-273.15^{\circ}$ $\mathrm{K}=^{\circ}\mathrm{C}+273.15^{\circ}$

Atoms and Elements

Element Interactions

Atoms
Protons: positively charged particles; located in nucleus of atom
Neutrons: neutrally charged particles; located in nucleus of atom
Electrons: negatively charged particles; surround the nucleus in levels called orbitals
Dalton’s Atomic Theory:

Every element is composed of tiny, indivisible particles called atoms.
All atoms of an element have identical properties; atoms of different elements are different from the atoms of all other elements.
Atoms combine in whole number ratios to form compounds.
Atoms may be combined, separated or reorganized during chemical reactions; atoms are not created or destroyed

Elements
Atomic Number: the number of protons in an element’s nucleus
Atomic Weight/Mass Number: the number of protons and neutrons in an element’s nucleus
Number of Neutrons = Atomic Weight — Number of Protons
Isotopes: elements with differing numbers of neutrons
Valence Electrons: electrons located in the orbital farthest from the nucleus; the column number (A or B) represents the number of valence electrons for each element.
Octet Rule: most atoms combine to have 8 valence electrons

Pure Substances: elements or compounds
Mixtures: a combination of two or more pure substances that are nonchemically bound
combination of two or more atoms in whole number ratios
Molecules: the smallest unit of a substance that preserves all the substance’s physical and chemical properties
Bonding
Covalent Bonding: bonding in which electrons are shared
Single Bond: two electrons are shared (-)
Double Bond: four electrons are shared (=)
Triple Bond: six electrons are shared (≡)
Ions: atoms with a charge created by the gain or loss of electrons
Ionic Bonding: bonding in which positive and negative ions are attracted and electrons are moved to other atoms
Cations: positively charged ions
Anions: negatively charged ions
Hydrogen Bonding: the intermolecular force between a hydrogen bound to a highly electronegative atom and another molecule’s two unshared electrons
Chemical Representations
Chemical Formula: a representation of molecules using symbols

Structural Formula: a diagram of molecules showing bonds between atoms

Next Table

Chemical Reactions

Nomenclature Overview

Chemical Change or Reaction: rearrangement of atoms to form a new substance; indicators include: energy release through light, sound or heat, electrical energy release or absorption, increase or decrease of temperature, production of gas or solid
(precipitate), color change and/or odor change
Percent Composition: the mass of the element divided by the mass of the compound
Theoretical Yield: the amount of product created during a reaction
Limiting Reactant: the reactant that determines how much yield is created
Writing Out Chemical Reactions
$\mathrm{Reactant 1}_{(l)}+\mathrm{Reactant 2}_{(s)} \quad \rightleftharpoons \quad \mathrm{Product 1}_{(aq)} + \mathrm{Product 2}_{(g)}$

(s) solid phase	(l) liquid phase
(g) gas phase	(aq) aqueous (water solution) phase
$\rightarrow$ “Yields,” separates reactants from products	(+) separates multiple reactants or products
$_{\Delta}^{\longrightarrow}$ Reactants are heated; Temperature unspecified	$_{Li}^{\longrightarrow}$

Identify Reactants and Products: write an unbalanced equation for the reaction; include phases, plus sign and yield arrow described above; predict missing chemicals if necessary.
Count Atoms of Each Elements in Reactants and Products: if compound is unchanged on both sides, count polyatomic ions as single units (ex: $NO^{-}_3$ ); identify elements appearing the least on reactant and product side and balance these first (balance H, O, and other atoms that appear more than once at the end); never change subscripts in a chemical formula
Add Coefficients to Balance: balance elements one at a time; write coefficients in lowest possible ratio (smallest possible whole numbers)
Check your results: Are the chemical formulas written correctly? Are the number of atoms of each element equal on both sides?

Types of Reactions
Oxidation: the loss of one or more electrons by a molecule
Reduction: the gain of one or more electrons by a molecule
Redox Reaction: a reaction in which both oxidation and reduction occur

Combination/Synthesis
Two substances or more yields one compound
D+E → DE

Decomposition
One compound yields two or more elements and/or compounds
DE → D+E

Acid/Base
An acid & base yield conjugate base and conjugate acid
$\mathrm{HA}+\mathrm{B} \rightarrow \mathrm{A}+\mathrm{HB}^+$

Single Replacement
A metal (or nonmetal) and a compound yields a new compound and a different metal (or nonmetal)
G+DE → GD+E

Double Replacement
Two compounds yields two different compounds (one is usually water, solid, or gas)
$J^+G^-+d^+E^- \rightarrow J^+E^-+D^+G^-$

Ions
Simple Cations: same name as their atom (ex: $\mathrm{Na}^+$ , sodium ion); if it can form more than one cation, roman numerals are added to indicate charge $(Fe^{3+}$ , iron(III) ion)
Simple Anions: same name as their atom plus-ide, nitride ion)
Ionic Compounds: cation’s name followed by anion name (ex: NaCl, sodium chloride)

Covalent Compounds

Prefix the less electronegative element if there is more than one atom followed by its name.
Prefix the more electronegative element if there is more than one atom followed by its name plus the -ide ending

Prefixes

1	mono-	5	penta-
2	di-	6	hexa-
3	tri-	7	hepta-
4	tetra-	8	octa-

Examples: $\mathrm{N}_2\mathrm{O}_3$ , dinitrogen trioxide; $\mathrm{Snl{_4}}$ tin tetraiodide

Acids
H + element: use the prefix hydro- followed by the element’s root name with -ic ending. (ex: HF, hydrofluoric acid)
H + -ite polyatomic ion: polyatomic ions ending in -ite change to -ous (ex: $\mathrm{HNO}_2$ nitrous acid)
H+ -ate polyatomic ion: polyatomic ions ending in -ate change to -ic (ex: $\mathrm{H}_2\mathrm{SO}_4$ , sulfuric acid)
Organic Compounds

Straight-Chain Hydrocarbons: prefix based on numbers of carbons
Short-Chain (1-3 Carbons)
–Alkanes: all carbons are single bonded; add -ane ending (ex: $\mathrm{C}_2\mathrm{H}_6$ , ethane)
–Alkenes: at least one carbon has a double bond; add -ene ending (ex: $\mathrm{C}_3\mathrm{H}_6$ , propene)
–Alkynes: at least one carbon has a triple bond; add -yne ending (ex: $\mathrm{C}_2\mathrm{H}_2$ , ethyne)
Long-Chain (4 or more Carbons)
–Alkanes: same as above
–Alkenes and Alkynes: ending is the same; number the carbons so that double bonds are triple bonds occur at the lowest numbers

Prefixes

1 meth-

2 eth-

3 prop-

4 but-

5 pent-

>5 See above

Energy and Change

Comparisons
Temperature v. Heat: Measure of energy v. energy transfers from hightemperature to low-temperature objects
Endothermic v. Exothermic: Absorbs energy v. releases energy
Nuclear Fission v. Fusion: Two way split of heavy nucleus into smaller nuclei (ex: uranium decay) v. small nuclei fuse together to make a larger nucleus (ex: suns and starts)
Radioactivity
Radioactivity: spontaneous emission of energy by an atomic nucleus
Radioactive Decay: the decomposition of an element over time
Alpha Particle: the nucleus of a helium atom
Beta Particle: a free electron Gamma Ray: a ray of light
Half Life: the period of time required for half of a substance to undergo radioactive decay
Photon Energy
Planck’s Equation (for finding the energy of a photon): Energy is equal to the frequency of light times Planck’s Constant; E=hv
Plank’s Constant
$h=6.626 \cdot 10^{-34} \mathrm{J} \cdot s$

Gas Laws

Acids and Bases

P = Pressure (in atm)
V = Volume (in L)
T = Temperature (in K)
k = A constant

n = Number of moles (in mols)
R = IGL Constant = 0.08206 $\frac{\mathrm{L}\cdot \mathrm{atm}}{\mathrm{K} \cdot \mathrm{mol}}$

Boyle’s Law
$\mathrm{PV}=\mathrm{k}$
$\mathrm{P}_1 \mathrm{V}_1=\mathrm{P}_2 \mathrm{V}_2$

Charle’s Law
$\mathrm{V}=\mathrm{kT}$
$\mathrm{\frac{V_1}{T_1}}=\mathrm{\frac{V_2}{T_2}}$

Avogadro’s Law
$\mathrm{V}=\mathrm{kn}$
$\mathrm{\frac{V_1}{n_1}}=\mathrm{\frac{V_2}{n_2}}$

Gay-Lussac’s Law
$\mathrm{P}=\mathrm{kT}$
$\mathrm{\frac{P_1}{T_1}}=\mathrm{\frac{P_2}{T_2}}$

Ideal Gas Law
$\mathrm{PV}=\mathrm{nRT}$

Acid: a substance that creates an $\mathrm{H}^+$ ion
Base: a substance that creates an $\mathrm{OH}^-$ ion
Titration: the determination of the concentration of a substance

pH
$\mathrm{pH}=-\log[H^+]\dfrac{mol}{Liter}$

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