3 Isotope Notation

• In this skill we will learn to calculate the number of subatomic particles from the nuclear symbol.
• The atomic number represents the number of protons in the atom, and is the number on the bottom left of the nuclear symbol.
• The mass number represents the total number of protons and neutrons in the atom, and is the number on the top left of the nuclear symbol.

Tips

• The number of protons is always equal to the atomic number!
• The number of neutrons can be calculated by subtracting the atomic number from the mass number.
• In a neutral atom, the number of electrons is equal to the number of protons.
• Use the image below to help format nuclear symbols.