AP Chem Unit 1 Vocab

Atom

The basic unit of a chemical element

Ion

An atom or group of atoms that has a positive or negative charge.

Isotope

Atoms of the same element with different numbers of neutrons, resulting in different mass numbers.

Mole

the amount of a substance that contains exactly 6.02214076 * 1023 'elementary entities' of the given substance

Molar Mass

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

Relative Abundance

The percentage of atoms with a specific atomic mass found in a naturally occuring sample of an element.

Avogadro’s Number

Number of units in one mole of any substance (defined as its molecular weight in grams), equal to 6.02214076 × 1023

Average Atomic Mass

The weighted average mass of the atoms in a naturally occurring sample of the element.

Matter

Anything that has mass and takes up space.

Pure Substance

Matter that has a fixed composition and distinct properties

Elements

A substance made up of only one type of atom, all with the same number of protons.

Compounds

A chemical substance composed of two or more different elements.

Empirical Formula

A chemical formula that gives the smallest whole number ratio of atoms in a compound.

Molecular Formula

What atoms and how many of each type of atom are present in a molecule.

Homogenous Mixtures

Contains two or more substances that are evenly distributed with each other.

Heterogeneous Mixtures

A mixture where throughout the solution the composition is not uniform.

Valence Electrons

Electrons in the outermost shell of an atom.

Photoelectron spectroscopy

A technique used to compare the relative energies of atoms, ions, and molecules

Ionization Energy

The amount of energy required to remove an electron from an isolated atom or molecule.

Atomic Radius

The average distance from the center of the atom's nucleus to its valence shell (outermost layer of electrons).

Electron Affrinity

The amount of energy released when an electron is added to a neutral atom to form an anion.

Electronegativity

The tendency of an atom or a functional group to attract electrons toward itself

Law of Octaves

Elements display similar properties at intervals of eight in the periodic table, suggesting periodicity in elemental properties.

Groups

Vertical columns in the periodic table, where elements share similar chemical properties and have the same number of valence electrons.

Periods

Horizontal rows in the periodic table that indicate the energy levels of the electrons in the atoms.

Ionic Compounds

A compound composed of a cation and an anion held together by electrostatic forces of attraction