1. neutral
equal
electrons
Atomic Number
= Protons
Element Symbol
Element Name
Mass Number

2. 3 3 4 3 7
Lithium
neutron
proton
electron
nucleus

3. element
neutrons 2 2
1 and 2 2
3 and 4
Helium-3 and Helium-4

4. An ion is a charge atom in which the electron number is different than the proton number.
If the electron number is less than the proton number, the particle is a positive ion called a cation.
If the electron number is greater than the proton number, the particle is a negative ion called an anion.
The charge is placed after the chemical symbol as a superscript. Mg 2+ Cl —
Magnesium cation
Chlorine anion