4.1.2 Mass Number, Atomic Number & Isotopes

• What two subatomic particles have an equal number in an atom?

  Protons and electrons.
• What is the overall charge of an atom?

  0.
• All atoms of a particular element have the same number of what?

  Protons.
• What is the number of protons in an atom called?

  Atomic number.
• What is the total number of protons and neutrons in an atom called?

  Mass number.
• What is an isotope?

  A variant of an element with the same number of protons but a different number of neutrons.
• What do atoms turn into after losing electrons?

  Ions.
• What happens when an atom gains electrons?

  It becomes a negative ion.
• What happens when an atom loses electrons?

  It becomes a positive ion.
• What can unstable isotopes do?

  Decay into other elements.
• What is ionisation?

  When an electron absorbs enough energy to leave an atom.