Chemistry Concepts Review

These flashcards cover essential chemistry concepts, definitions, and trends to aid in exam preparation.

Matter

Anything with mass and volume.

Element

One type of atom.

Compound

Two or more elements chemically bonded.

Physical change

Change that does not produce a new substance.

Chemical change

Change that produces a new substance.

Proton

Positively charged subatomic particle.

Neutron

Neutral subatomic particle.

Electron

Negatively charged subatomic particle.

Atomic number

The number of protons in an atom.

Mass number

Total number of protons and neutrons in an atom.

Mole

A quantity of substance equal to 6.022 × 10²³ entities.

Molar mass

Mass of a substance (in grams) per mole.

Energy relationship

Higher frequency means higher energy; lower wavelength.

Pauli Exclusion Principle

An orbital can hold a maximum of two electrons with opposite spins.

Hund’s Rule

Electrons fill orbitals singly before pairing.

Atomic radius trend

Increases down a group and decreases across a period.

Ionization energy trend

Decreases down a group and increases across a period.

Electronegativity trend

Decreases down a group and increases across a period.

Ionic bond

A bond formed by transfer of electrons.

Covalent bond

A bond formed by sharing electrons.

Octet rule

Atoms tend to form bonds to have eight valence electrons.

Polar bond

A bond with unequal sharing of electrons.

Nonpolar bond

A bond with equal sharing of electrons.

Empirical formula

Simplest ratio of elements in a compound.

Molecular formula

Actual number of atoms in a molecule.

VSEPR theory

Electron groups around a central atom determine shape.

Electron geometry

Shape considering all electron groups.

Molecular geometry

Shape considering only the atoms.

sp hybridization

Linear molecular shape.

sp2 hybridization

Trigonal planar molecular shape.

sp3 hybridization

Tetrahedral molecular shape.

Bond order formula

(Number of bonding electrons - Number of antibonding electrons) / 2.

Paramagnetic

Character of an atom with unpaired electrons.

Limiting reactant

The reactant that is consumed first in a reaction.

Percent yield

(Actual yield / Theoretical yield) × 100.

Molarity

Concentration measured as moles of solute per liter of solution.

Strong electrolyte

Substance that completely dissociates in solution.

Weak electrolyte

Substance that partially dissociates in solution.

Arrhenius acid

A substance that produces H⁺ ions in solution.

Arrhenius base

A substance that produces OH⁻ ions in solution.

Strong acids

Acids that fully dissociate in solution: HCl, HBr, HI, HNO₃, H₂SO₄, HClO₄.

Oxidation

Loss of electrons.

Reduction

Gain of electrons.

Endothermic reaction

A reaction that absorbs heat.

Exothermic reaction

A reaction that releases heat.

Strongest intermolecular force (IMF)

Hydrogen bonding.

Weakest intermolecular force (IMF)

London dispersion forces.

Cause of stronger London dispersion forces

More electrons or larger molecular size.

Like dissolves like

Polar substances dissolve in polar solvents.