Elements, Isotopes and relative atomic mass

• What is an element ?


  An element is a substance made up of only one type of atom
• Approximately how many different element are there ?

  100 ; 118 to be exact.
• What is an isotope ?

  Isotopes are different forms of the same element

  • Has the same number of protons but a different number of neutrons in its nucleus.
• Carbon 12 and Carbon 12 are isotopes but how do they differ ?

  Different number of Neutrons

  • Carbon - 12 has 6 neutrons
  • Carbon - 13 has 7 neutrons
• What does relative atomic mass mean ?

  Average mass of an element's isotopes, taking into account the abundance and mass number of each isotope .
• What is the formula for Relative Atomic Mass ?

  Sum of: ( Isotope abundance X Isotope mass number ) / sum of abundances of all isotopes
• Do isotopes of an element all chemically react in the same way ?

  Yes.
• As long as the same number of protons remains the same , it’s still the same element.
• Abundance

  How common or rare the isotope is

  OR

  How much of the quantity of the isotope that’s present.