Atoms and Elements Vocabulary

Atom

the basic unit of a chemical element.

Nucleus

Center of an atom containing protons and neutrons

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge and is found outside of the nucleus of an atom

Electron Shell/Energy Level

An energy level representing the distance of an electron from the nucleus of an atom

Atomic Number

the total number of protons in the nucleus of an atom

Atomic Mass Number

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

Element

A substance made of only one type of atom that cannot be broken down into simpler substances

Chemical Symbol

a one or two letter abbreviation of the name of an element

Periodic Table of the Elements

A table that classifies elements by their physical and chemical properties

Molecule

A substance made of two or more atoms that are held together by chemical bonds