Chapter 2: Atoms, Ions, and Compounds

Nucleus

A positively charged region at the center of the atom

Shell

A group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level

Proton

A positively charged, subatomic particle found in the nucleus of every atom

Neutron

A subatomic particle with no charge, found in the nucleus of every atom except that of simple hydrogen

Electron

A negatively charged subatomic particle that can be either bound to an atom or free (delocalised)

Proton Number

The number of protons in the nucleus of an atom; also known as atomic number

Relative Atomic Mass

The weighted mean mass if an atim of an element compared with one-twelfth of the mass of an atom of carbon-12

Ion

A positively or negatively charged atom or (covalently bonded) group of atoms (a polyatomic ion), where the number of electrons is different from the number of protons

Cation

A positively charged ion with fewer electrons than protons

Anion

A negatively charged ion with more electrons than protons

Relative Isotopic Mass

The mass of an atom of an isotope compared with one-twelfth og the mass of an atom of carbon-12

Binary Compound

A compound containing two elements only

Polyatomic Ion

An ion containing more than one ion

Ionic Compound

An electrically neutral compound consisting of positive and negative ions

Element

A substance that can't be broken down by non-nuclear reactions

Diatomic Molecule

A molecule that contains two atoms that are chemically bonded

Covalent Compound

A compound formed via sharing a pair of electrons