Essential Memorization

What are the seven diatomic elements?

H2, N2, O2, F2, Cl2, Br2, I2

Mnemonic for diatomic elements

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What is Avogadro's number?

6.022 × 10^23 particles/mol

SI unit of mass

kilogram (kg)

SI unit of length

meter (m)

SI unit of temperature

kelvin (K)

SI unit of amount of substance

mole (mol)

Density equation

density = mass / volume

Formula rearrangement for mass

mass = density × volume

Formula rearrangement for volume

volume = mass / density

Charge of proton

+1

Charge of neutron

0

Charge of electron

−1

Mass of proton

≈1 amu

Mass of neutron

≈1 amu

Mass of electron

≈0 amu (negligible)

Atomic number

Number of protons

Mass number

Protons + neutrons

Atomic mass

Weighted average of naturally occurring isotopes

Cation

Positively charged ion

Anion

Negatively charged ion

Formula of ammonium

NH4+

Formula of hydroxide

OH−

Formula of nitrate

NO3−

Formula of nitrite

NO2−

Formula of carbonate

CO3^2−

Formula of hydrogen carbonate

HCO3−

Formula of sulfate

SO4^2−

Formula of sulfite

SO3^2−

Formula of phosphate

PO4^3−

Formula of acetate

C2H3O2−

Formula of cyanide

CN−

Formula of chromate

CrO4^2−

Formula of dichromate

Cr2O7^2−

Formula of peroxide

O2^2−

Formula of hydrogen sulfate

HSO4−

Formula of hydrogen sulfite

HSO3−

Formula of hydrogen phosphate

HPO4^2−

Formula of chlorate

ClO3−

Formula of perchlorate

ClO4−

Formula of chlorite

ClO2−

What is a molecule?

Two or more atoms covalently bonded together

What is a formula unit?

Lowest whole-number ratio of ions in an ionic compound

Empirical formula

Lowest whole-number ratio of atoms

Molecular formula

Actual number of each atom in a molecule

Ionic bond

Electrostatic attraction between oppositely charged ions

Covalent bond

Sharing of electrons between atoms

General rule for ionic compounds

Total positive charge equals total negative charge

Naming ionic compounds

Cation first

Variable-charge metals

Use Roman numerals to indicate metal charge