GCSE Combined Science (AQA)

622 videos | 38 hours

Mass Number & Isotopes

Please subscribe to watch this video.

This, and all other videos, are included in our premium subscriptions.

Premium accounts get access to all videos.

Atomic structure Atoms and isotopes

Mass Number & Isotopes

4:24 Atomic Structure
Spec 4.4.1.2
Previous Atomic Number Next Ions
  • The mass number of an atom equals the total number of protons and neutrons in its nucleus.
  • In a nucleus diagram, neutrons are represented by plain green circles, and protons by blue circles with a plus sign.
  • The mass number is the total number of protons and neutrons, calculated by adding them together.
  • In atomic notation, the top number represents the mass number.
  • The number of neutrons can be found by subtracting the atomic number (bottom number) from the mass number.
  • The atomic number indicates the number of protons and electrons in the atom.
  • Isotopes are atoms with the same atomic number but different mass numbers.
  • Isotopes have the same chemical properties but can have different physical properties.
  • Chemical properties involve the types of reactions and bonds formed, determined by electron arrangement.
  • Physical properties include density and radioactivity, determined by the nucleus.
  • Isotopes have the same electron arrangement, leading to similar chemical reactions.
  • Isotopes of the same element have different nuclei, which can result in different physical properties.

Please subscribe to access these revision notes.

This, and all other video notes, are included in our premium subscriptions.

Premium accounts get access to all videos and revision notes.