Intro to Periodic Table 2025

Front

The smallest whole unit of matter.

Back

atom

Front

The center of an atom.

Back

nucleus

Front

The positively charged part of an atom; found in the nucleus.

Back

proton

Front

The part of the atom that has no charge; found in the nucleus.

Back

neutron

Front

The negatively charged part of an atom; found orbiting the nucleus.

Back

electron

Front

The number of protons also corresponds to its:

Back

atomic number

Front

The number of protons plus neutrons (P + N).

Back

atomic mass

Front

The letter(s) that represent the element.

Back

atomic symbol

Front

A substance made of just one type of atom which cannot be broken down or changed into another substance.

Back

element

Front

A chart of elements, placed in atomic number order.

Back

Periodic Table