Isotopes

What is an Isotope?

Isotope: Different versions of an element where atoms have more or less neutrons.

• Video: Tyler DeWitt - What are Isotopes?
• Mass Number: Actual mass of one specific atom
• Atomic Mass: Average mass of all the atoms of a specific element
  • Video: Tyler DeWitt - The Difference between Mass Number and Atomic Mass
• When the Mass Number of an atom is the same as the Atomic Mass...
  • This is the most commonly found, abundant (Normal) form of the element.
  • No special naming is required.
• When the Mass Number is higher or lower than the Atomic Mass,..
  • This is not the most abundant form of the element and is an isotope.
  • These isotopes require special names.

Naming Isotopes

It is important to know what kind of carbon or oxygen you are using. If you are using an atom that is heavier or lighter than normal that can make a difference. Somehow we have to be able to name the atoms and indicate the new mass that is not the same as the periodic table. We can do this two ways.

Writing out the Name

• If you are writing out the full name of an atom, or just the symbol, you can put the atom's mass (mass number) after the name or symbol with a dash connecting them.
  • Example #1: A carbon atom that has 2 extra neutrons raising the mass from 12 to 14 would be called...
    • Carbon-14 or C-14
    • Pronounced "Carbon 14"
  • Example #2: A carbon atom that has 2 less neutrons, lowering the mass from 12 to 10 would be called...
    • Carbon-10 or C-10
  • Example #3: A normal carbon atom with the most abundant mass that is the same as the periodic table can be called...
    • Carbon or C (no mass numbers required)
    • Carbon-12 or C-12 (you CAN put the numbers on if you would like.)

Symbol - Four Corners

• Each element symbol has four corners where information can be placed to help name special atoms. The mass number of an atom goes in the upper right corner of the symbol.
• Video: Tyler DeWitt - Isotope Notation