Chem 1-3

What is the formula for density?

d = m/V (mass divided by volume)

What is the Fahrenheit-to-Celsius conversion formula?

°F = 1.8(°C) + 32 — rearranged: °C = (°F − 32)/1.8

What is the Celsius-to-Kelvin conversion formula?

K = °C + 273.15

How many particles are in 1 mole (Avogadro's Number)?

6.022 × 10²³ particles

What's the formula for calculating atomic mass from isotopes?

Atomic mass = Σ (fraction of isotope × mass of isotope) — weighted average

kilo- (k) means multiply by:

1000 (10³)

milli- (m) means multiply by:

0.001 (10⁻³)

centi- (c) means multiply by:

0.01 (10⁻²)

1 lb equals how many kg?

1 lb = 0.454 kg

What relationship exists between mL and cm³?

1 mL = 1 cm³ exactly

What SI unit is used for temperature?

Kelvin (K) — absolute scale, no negative values

What SI unit is used for mass?

Kilogram (kg)

An intensive property (like density)…

Stays the same no matter the amount of substance present

Rule: leading zeros (before the first nonzero digit)…

Are NEVER significant — they only locate the decimal point

Rule: interior zeros (between two nonzero digits)…

Are ALWAYS significant

For MULTIPLICATION/DIVISION, the answer's sig figs should match:

The value with the FEWEST significant figures

For ADDITION/SUBTRACTION, the answer's precision should match:

The value with the FEWEST decimal places

Which particle has essentially NO significant mass?

Electron — ~2000x lighter than protons/neutrons

Formula: Mass Number (A) = ?

Protons + neutrons

Formula: Number of Neutrons = ?

Mass Number (A) − Atomic Number (Z)

Formula: Charge of an ion = ?

protons − electrons

Formula for converting moles → number of particles:

moles × 6.022×10²³

Formula for converting grams → moles:

grams ÷ molar mass

Formula: Formula Mass (of a compound) = ?

Sum of all atomic masses of atoms in the formula

Formula: Mass Percent of element X in a compound = ?

(mass of X in 1 mol compound ÷ molar mass of compound) × 100%

Formula: Finding n to go from empirical → molecular formula:

n = molar mass ÷ empirical formula mass

Molecular → empirical formula: what do you divide subscripts by?

The greatest common factor of all subscripts

Ionic bonds form between which types of elements?

A metal and a nonmetal (electron transfer)

Covalent bonds form between which types of elements?

Two or more nonmetals (electron sharing)

How do metals with INVARIANT charge get named?

Metal name + nonmetal root + "-ide" (no Roman numeral needed)

How do metals with VARIABLE charge get named?

Include a Roman numeral showing the metal's charge (e.g. copper(II) oxide)