Atom

The smallest object that retains properties of an element. Composed of electrons and a nucleus (containing protons and neutrons).

Chemical changes

Processes or events that have altered the fundamental structure of something.

Electron

One of the parts of the atom having a negative charge. Indivisible particle with a charge of -1.

Element

Substance consisting of only one type of atom.

Particle

Small portion of matter.

Solution

Mixture of a solid and a liquid where the solid never settles out, for example, saltwater.