Chem Exam 1

Mass

Measure of the amount of matter in an object.

Matter

Anything that has mass and takes up space.

Extensive properties

Properties that depend on the amount of matter, such as mass and volume.

Intensive properties

Properties that do not depend on the amount of matter, like density and boiling point.

Significant Figures (SigFigs)

Digits in a measurement that contribute to its precision.

Physical Change

A change that alters the form of a substance but not its identity.

Chemical Change

A change in which one or more substances are converted into different substances.

Isotope

Atoms of the same element that have different numbers of neutrons.

Mole

A counting unit used in chemistry, equal to Avogadro's number, 6.02 x 10^23.

Molar Mass

The mass of one mole of a substance, typically expressed in grams per mole.

Density

Mass per unit volume of a substance, calculated as density = mass/volume.

Empirical Formula

The simplest whole number ratio of atoms in a compound.

Molecular Formula

The actual number of atoms in a molecule of a compound.

Quantum Theory

A theory that describes the behavior of matter and energy at atomic and subatomic levels.

Heisenberg Uncertainty Principle

States that it is impossible to know both the position and velocity of an electron simultaneously.

Aufbau Principle

Electrons fill the lowest energy orbitals first.

Hund’s Rule

Within a sublevel, place one electron per orbital before pairing them.

Noble Gas Configuration

A method of writing electron configurations using the symbol of the nearest noble gas.

Law of Conservation of Mass

Mass is neither created nor destroyed in a chemical reaction.

Atomic Number

The number of protons in the nucleus of an atom, which determines the element.

Absolute Zero

The theoretical lowest possible temperature, 0 Kelvin, where molecular motion stops.