1. Isotopes

2. What are Isotopes?
Isotopes are atoms of the same element with different numbers of neutrons.
Each isotope has the same chemical properties, but different atomic masses.
The atomic mass is written after a dash
Carbon-12 means the isotope has a mass of 12.
Carbon-14 means the isotope has a mass of 14.

3. Examples
Hydrogen-1
Hydrogen-2
Hydrogen-3

4. Sample Problems: For Iodine- 128, find: Atomic mass Atomic number
Number of protons
Number of neutrons
Number of electrons

5. Answer: For Iodine- 128, find: Atomic mass 128 Atomic number 53
Number of protons 53
Number of neutrons =75
Number of electrons 53

6. Isotopic Symbols
2512Mg
73Li