The structure of an atom

electron arrangements

The ________ may change with the absorption of electromagnetic radiation (move further from the nucleus; a higher energy level) or by the emission of electromagnetic radiation (move closer to the nucleus; a lower energy level)

mass

Most of the ________ of an atom is concentrated in the nucleus.

Atoms

________ are very small, having a radius of about 1 × 10- 10 metres.

Proton

relative mass = 1 charge = +1

Neutron

relative mass = 1 charge = 0