Atom - The smallest unit of an element that has all the properties of that element. The basic building block of all matter.

9. Valence electrons

electrons located in the outside energy level.

Compound

A combination of substances that are chemically combined.

6. Mixture

A combination of substances that are physically combined.

Electron

A particle that has a negative charge and orbits the nucleus of an atom.

Proton

A particle that has a positive charge found in the nucleus of an atom.

4. Neutron

A particle that has no charge and is Found in the nucleus of an atom.

8. Chemical formula

A ratio of elements in a compound.

5. Molecule

The smallest unit of a compound that has all the properties of the compound.

Atom

The smallest unit of an element that has all the properties of that element. The basic building block of all matter.