8-5.1 The Structure of the Atom

The Nucleus

The Nucleus

• The central part of an atom.

• Composed of protons and neutrons.

• Contains most of an atom's mass

Proton

• Positively charged particles.

• Help make up the nucleus of the atom.

• Equal to the atomic number of the atom.

• Contribute to the atomic mass.

• Equal to the number of electrons.

Neutron

• Neutral particles; have no electrical charge.

• Help make up the nucleus of the atom.

• Contribute to the atomic mass.

Electron

• Negatively charged particles.

• Found outside the nucleus of the atom.

• Move so rapidly around the nucleus that they create an electron cloud.

• Mass is insignificant when compared to protons and neutrons.

• Equal to the number of protons.

• Involved in the formation of chemical bonds.