Chemistry Final Exam Key Concepts: Atomic Structure, Bonding, and Gas Laws

What is an element?

A pure substance made of one type of atom that cannot be broken down chemically.

What is a compound?

Two or more elements chemically bonded in a fixed ratio.

What is a mixture?

A physical combination of substances with variable composition.

What distinguishes physical changes from chemical changes?

Physical changes do not form new substances, while chemical changes do.

What are signs of a chemical change?

Gas production, color change, temperature change, and precipitate formation.

What is the atomic number?

The number of protons in an atom.

What is the mass number?

The sum of protons and neutrons in an atom.

What is the charge of a neutral atom?

The number of protons equals the number of electrons.

What are isotopes?

Atoms with the same number of protons but different numbers of neutrons.

What is the maximum number of electrons in the s, p, and d orbitals?

s = 2, p = 6, d = 10.

What are valence electrons?

Electrons in the outermost shell that determine bonding behavior.

What trend does atomic radius follow in the periodic table?

Increases down a group and decreases left to right.

What is ionization energy?

The energy needed to remove an electron from an atom.

What is electronegativity?

The attraction for electrons in a bond, highest near fluorine.

What is an ionic bond?

A bond formed by the transfer of electrons from a metal to a nonmetal.

What is a covalent bond?

A bond formed by the sharing of electrons between nonmetals.

What shape does CH₄ have?

Tetrahedral.

What is the strongest type of intermolecular force?

Hydrogen bonding.

What is the empirical formula?

The simplest whole-number ratio of elements in a compound.

What is the ideal gas law equation?

PV = nRT, where P is pressure, V is volume, n is number of moles, R is the gas constant, and T is temperature in Kelvin.

What happens to gas volume if temperature increases at constant pressure?

Volume increases.

What is the difference between empirical and molecular formulas?

Empirical formulas show simplest ratios while molecular formulas show actual atom counts.

What are the steps for mole calculations?

Find molar mass, convert units, and use dimensional analysis.

What is Boyle's Law?

Pressure and volume are inversely related (P1V1 = P2V2).

What is the significance of coefficients in balanced equations?

They indicate mole ratios of reactants and products.