CHem chapter 1

Element

A substance made of only one type of atom.

Isotope

Atoms with the same protons but different neutrons and mass.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a net charge.

Atomic Number (Z)

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

Mass Number (A)

The total number of protons and neutrons in the nucleus of an atom.

Subatomic particles

Particles that are smaller than atoms, including protons, neutrons, and electrons.

Electronegativity

The ability of an atom to attract electrons.

Ionisation Energy

The energy to remove an electron from an atom.

Valence Electrons

Electrons in the outermost shell of an atom, which are involved in chemical reactions.

Schrodinger Model

A model that treats electrons as waves and includes subshells.

Aufbau Principle

A principle that states electrons occupy the lowest energy orbitals first.

Pauli Exclusion Principle

A principle that states no two electrons can occupy the same quantum state within an atom.

Diatomic Molecule

A molecule composed of two atoms, which can be of the same or different elements.

Covalent Network Lattice

A structure made up of atoms that are bonded covalently in a continuous network.

Monatomic Element

An element that exists as individual atoms, such as noble gases like helium, neon, and argon.

Octet Rule

The tendency of atoms to prefer to have eight electrons in their valence shell to achieve stability.

Noble Gases

Elements in Group 18 of the periodic table that are characterized by their lack of reactivity due to having full valence shells.

Chemical Symbol

A notation of one or two letters representing a chemical element.

Critical Elements

Elements that are in limited supply unless recycled; their depletion could affect industry and technology.

Rare Earth Elements

A group of 17 elements in the periodic table that are important to various technological applications.