Chapter 1-6 Notes: Basic Atomic Structure and Bonding

A set of vocabulary flashcards covering core concepts from the notes on elements, atoms, shells, ions, and bonding.

Element

One of the 92 naturally occurring substances that make up matter; each element is defined by its nucleus and number of protons.

Atom

The basic unit of a chemical element, consisting of a nucleus (protons and neutrons) and electrons surrounding it; neutral when protons equal electrons.

Atomic number

The number of protons in an atom’s nucleus; in a neutral atom it also equals the number of electrons.

Neutral atom

An atom with no overall charge because it has equal numbers of protons and electrons.

Protons

Positively charged particles in the nucleus; determine the element’s identity and atomic number.

Electron shell

Regions around the nucleus where electrons reside; first shell holds up to 2 electrons, second up to 8, third up to 18 (often 8 is the stable value).

Octet

Eight electrons in the outermost shell; a stable (unreactive) configuration, also called the octet rule.

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Ion

An atom or molecule with a net electric charge due to gained or lost electrons.

Ionic bond

A bond formed by transfer of electrons from one atom to another, creating oppositely charged ions that attract; often yields salts.

Covalent bond

A bond formed by sharing electrons between atoms; shared electrons count for both atoms (e.g., CO₂).

Salt

An ionic compound formed by ionic bonding; typically crystallizes and is electrically neutral overall.

Nucleus

The center of the atom where protons and neutrons reside; its composition defines the element.

Electron

A negatively charged particle in the electron cloud surrounding the nucleus; involved in bonding and ion formation.

Electron cloud

The region around the nucleus where electrons move and can be transferred between atoms.

Compound

A substance formed when two or more elements join together; its properties differ from the individual elements.

Molecule

Two or more atoms bonded together; can consist of the same or different elements.