A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Definition: Atoms with the same number of protons, but differing numbers of neutrons. Isotopes are different forms of a single element.
Examples: Carbon 12 and Carbon 14 are both isotopes of carbon, one with 6 neutrons and one with 8 neutrons (both with 6 protons).

