Elements, Compounds and Mixtures

Additional Notes

Atom: Smallest particle of an element

Molecule: Combination of two or more atoms of the same element

Element: Composed of only one type of atom and cannot be broken down into simpler substances by chemical methods

Compound: a substance containing two or more elements chemically joined together (eg NaCl)

Mixture: consists of 2 or more substances not chemically combined together

Group (columns): Elements in a group share similar chemical and physical properties

Period (rows): Elements in a period have the same number of energy shell

Mass number: Number of protons + neutrons

Atomic number: Number of protons