CHAPTER 16 – ATOMS AND ELEMENTS Subatomic particles
Scientists now know that an atom is made up of smaller particles called subatomic particles. There are three subatomic particles: • protons • neutrons • electrons
Electron orbits
Electron Neutron Proton Nucleus
: Fig. 16.4 Structure of an atom
The following table summarises the properties of the three subatomic particles: Subatomic particle
Proton
Neutron Electron
Mass 1 1
Charge
Positively charged (+1) No charge (0)
1/1836 Negatively charged (–1)
Location in the atom
Nucleus Nucleus
Orbiting the nucleus
CONCENTRATE! Protons and neutrons have the same mass. Electrons have so little mass that scientists treat their mass as zero.
? TEST TUBE
4. Name the two subatomic particles that are located in the nucleus of the atom. 5. Name the subatomic particle that has a positive charge. 6. Name the subatomic particle that has the lowest mass.