1. Element Box page 7 Si 28.086 Silicon 14 Atomic number Chemical Symbol
Atomic mass
Name

2. amu = atomic mass unit
The mass of subatomic particles is so small that a special unit of measurement is needed just for them.
1 proton = 1 amu
1 neutron = 1 amu
1 electron = < 1amu
Remember most of an atom’s mass is in the nucleus: p + n
* see Gateway p15 : draw each example

3. The number of protons + the number of neutrons
Atomic number
The number of protons found in the nucleus
Each atom of an element has a specific number of protons and electrons so no two elements are the same.
Atomic Mass
The number of protons + the number of neutrons
Most of an element’s mass is in the nucleus.

4. Helpful Hints Mass - Atomic # # Neutrons Atomic # =
Protons = all the same #
Electrons =