Atomic number is used to identify what element an atom belong to
The atomic number is the number of protons in the nucleus
The mass number of an atom is the number of protons + neutrons
If atoms have the same atomic number but different mass number they are...
Isotopes were first suggested by Frederick Shoddy in 1913
The periodic table is a list of all known elements ordered by atomic number
The modern periodic table contains 118 elements