GCSE Combined Science (AQA)

622 videos | 38 hours

Atomic structure and the periodic table A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

Compounds

2:53 Atoms, Elements and Compounds
Spec 4.1.1.1
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  • Compounds consist of two or more different elements chemically combined.
  • Atoms can be represented by colored spheres; blue for element A and red for element B.
  • When atoms combine chemically, they form a compound containing the original elements.
  • Compounds are a type of molecule, which are made of two or more atoms bonded together.
  • Molecules can consist of atoms from the same or different elements.
  • Only molecules made from different elements are considered compounds.
  • Elements in a compound are present in fixed proportions.
  • Example: Carbon dioxide (CO2) always contains one carbon atom and two oxygen atoms.
  • Example: Sodium chloride (NaCl) always contains one sodium atom and one chlorine atom.
  • Properties of compounds differ from the properties of their constituent elements.
  • Example: Hydrogen and oxygen, both gases, react to form water, a non-flammable liquid.
  • The reaction of hydrogen and oxygen to form water is not a balanced equation in the example provided.

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