Atomic Structure

Atom

Basic building block of matter

Subatomic particles

Protons; neutrons; electrons

Nucleus

Protons + neutrons

Electron cloud

Electrons

Nucleus mass

Nearly all atomic mass

Electron cloud volume

Nearly all atomic volume

Proton

Positive; nucleus; p⁺

Neutron

Neutral; nucleus; n⁰

Electron

Negative; electron cloud; e⁻

Proton determines

Element identity; atomic number

Change in protons

New element

Change in neutrons

Isotope

Change in electrons

Ion

Electron role

Chemical bonding

Atomic number

Number of protons

Mass number

Protons + neutrons

Average atomic mass

Weighted average of naturally occurring isotopes

Mass number

Whole number

Average atomic mass

Decimal on periodic table

Neutral atom

Protons = electrons

Ion

Atom with a net charge

Cation

Positive ion; lost electrons; more protons than electrons

Anion

Negative ion; gained electrons; more electrons than protons

Isotope

Same protons; different neutrons

Number of neutrons

Mass number − atomic number