The atomic number is the number of protons in the nucleus
Atomic number is used to identify what element an atom belong to
An element is a substance that cannot be chemically broken down into a simpler substance
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