Organization of the Periodic Table

Atomic Number

-the number of protons in the nucleus
-tells us the identity of the element

Isotopes

-atoms with the same number of protons but different numbers on neutrons
-Example: Carbon
.Carbon-11
6 protons
5 neutrons
unstable

.Carbon-12
6 protons
6 neutrons
stable

.Carbon-13
6 protons
7 neutrons
stable

.Carbon-14
6 protons
8 neutrons
unstable