- Atomic number equals the number of protons.
- Atomic mass equals the number of protons + neutrons.
- For a neutral atom, the number of protons equals the number of electrons.
- Round the atomic mass to the nearest whole number using standard rounding rules (≥ 0.5 rounds up, < 0.5 rounds down).
- Number of neutrons = Atomic mass (rounded) - Atomic number.
Oxygen (O):
- Atomic # = 8
- Atomic Mass = 16 (rounded from 15.999)
- # of Protons = 8
- # of Neutrons = 8 (16 - 8)
- # of Electrons = 8
Zinc (Zn):
- Atomic # = 30
- Atomic Mass = 65 (rounded from 65.39)
- # of Protons = 30
- # of Neutrons = 35 (65 - 30)
- # of Electrons = 30
Lithium (Li):
- Atomic # = 3
- Atomic Mass = 7 (rounded from 6.941)
- # of Protons = 3
- # of Neutrons = 4 (7 - 3)
- # of Electrons = 3
Silicon (Si):
- Atomic # = 14
- Atomic Mass = 28 (rounded from 28.086)
- # of Protons = 14
- # of Neutrons = 14 (28 - 14)
- # of Electrons = 14
Boron (B):
- Atomic # = 5
- Atomic Mass = 11 (rounded from 10.81)
- # of Protons = 5
- # of Neutrons = 6 (11 - 5)
- # of Electrons = 5
Bromine (Br):
- Atomic # = 35
- Atomic Mass = 80 (rounded from 79.904)
- # of Protons = 35
- # of Neutrons = 45 (80 - 35)
- # of Electrons = 35
Parent Tip: Review the logic above to help your child master the concept of atoms family worksheet.
