Atoms and the Periodic Table

(Atomic Theory/ Periodic Table)

Atom

The smallest particle that can still be considered an element

Electron

A subatomic particle with a negative charge that orbits the nucleus of an atom.

Nucleus

The central part of an atom, consisting of protons and neutrons, and containing most of the atom's mass.

Proton

A positively charged subatomic particle found in the nucleus of an atom. It determines the atomic number and identity of an element.

Neutron

A subatomic particle with no charge, found in the nucleus of an atom, that contributes to the atomic mass but not the atomic number.

Atomic Number

The number of protons in the nucleus of an atom, which defines the element and determines its position on the periodic table.

Isotope

Atoms of the same element that have the same number of protons, but a different number of neutrons, resulting in a different mass.

Atomic Mass

The weighted average mass of an atom's isotopes, measured in atomic mass units (amu), reflecting both the number of protons and neutrons in the nucleus.

Periodic Table

A chart arrangement of the chemical elements, organized by increasing atomic number, according to the repeating pattern of their properties.

Chemical Symbol

A one- or two-letter abbreviation used to represent a chemical element.

Period

The rows in a periodic table (left to right)

Group

The columns in a periodic table. These elements have similar characteristics. (up and down)