Chemistry unit 2

These revision cards give an overview of the entire Chemistry unit.

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Atoms

  • Atoms consist of electrons surrounding a nucleus that contains protons and neutrons.
  • The number of electrons in the outermost shell has a direct link to the group number that the element is found in.
  • Protons have a mass number of 1, and a charge of +1.
  • Neutrons have a mass number of 1, and a charge of 0.
  • Electrons have an extremely small mass number, and a charge of -1.
  • The mass number is the TOP NUMBER.
  • The atomic number is the BOTTOM NUMBER.
  • Elements consist of one type of atom only.
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Chemical Bonding.

  • Ions are electrically charged particles formed when atoms lose or gain electrons.
  • Metal atoms lose electrons to become postively charged ions.
  • Non-metal atoms gain electrons to become negatively charged ions.
  • The strong forces of attraction between oppositely charged ions are called ionic bonds.
  • These strong forces therefore require a lot of energy to be broken, and consequently ionic bonds have high melting and boiling points.
  • SHARING ELECTRONS - covalent bonding.
  • TRANSFERRING ELECTRONS - ionic bonding.
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