$N_A = 6.022 \times 10^{23}$ particles per mole

$n = \frac{m}{M}$

• n = moles, m = mass (g), M = molar mass (g/mol)

Ionic bonding: Electron transfer between a metal and a nonmetal creates oppositely charged ions held together by electrostatic attraction.

• Forms extended ionic lattices
• High melting points and electrical conductivity when molten or dissolved

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Bond polarity: Determined by electronegativity difference between bonded atoms.

• Nonpolar covalent: electrons shared equally or nearly equally
• Polar covalent: electrons shared unequally, creating partial charges

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Weakest IMF; present in all molecules

• Caused by temporary electron cloud distortions (instantaneous dipoles)
• Strength increases with molecular size/polarizability

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Attraction between positive end of one polar molecule and negative end of another

• Stronger than LDF for similar-sized molecules
• Only in polar molecules (permanent dipole)

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Chemical equation: Reactants -> Products Balancing rules:

1. Write correct formulas for all reactants and products

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Spectator ions: Ions that do not participate in reaction (appear unchanged on both sides) Precipitate: Insoluble solid formed in solution Net ionic equation: Shows only species that actually change

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Rate law: Rate = $k[A]^m[B]^n$

• Must be determined experimentally
• Cannot be determined from balanced equation

Rate of change of concentration of reactant or product over time: $\text{Rate} = -\frac{1}{a}\frac{d[A]}{dt} = \frac{1}{b}\frac{d[B]}{dt}$

Experimental measurement of heat changes

• Coffee cup calorimeter: Constant pressure (q = DeltaH)
• Bomb calorimeter: Constant volume (q = DeltaE)

(C):** Energy required to raise temperature by 1 K

• Specific heat capacity (c): Energy for 1 gram by 1 K
• Molar heat capacity: Energy for 1 mole by 1 K

State where forward and reverse reactions occur at equal rates

• Concentrations of reactants and products remain constant
• Reaction continues at molecular level (not stopped)

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For reaction: $aA + bB \rightleftharpoons cC + dD$ $K_{eq} = \frac{[C]^c[D]^d}{[A]^a[B]^b}$ Pure solids and pure liquids are NOT included in K expression.

pH: Measure of $[H^+]$ $pH = -\log[H^+]$ pOH: Measure of $[OH^-]$

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Strong acids (completely dissociate):

• $HCl$, $HBr$, $HI$, $HNO_3$, $HClO_4$, $H_2SO_4$ (first $H^+$ only) Strong bases (completely dissociate):

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Entropy ($S$): Measure of disorder or energy dispersal

• Units: J/mol - K
• Standard entropy ($S degrees$): Entropy at standard conditions (1 bar, 25 degrees C)

$\Delta S$ positive when:

• Solid -> liquid -> gas
• More moles of gas produced

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