Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

9.6Unit 2: States of matter, atoms and compounds

Compounds and formulae

5 min read 4 parts Lesson 6 of 7 1 quiz

0%read
Lesson summary

9.6 Compounds and formulae — CHECKPOINT (CHEMISTRY) notes: Distinguish elements from compounds, name compounds and use formulae.Compound = a substance in which two or more different kinds of atom are bonded togetherBonding = the tight joining of atomsSodium atoms bonded with chlo…

  • Properties
  • Metal first
  • Oxygen compounds
  • Subscript number
  • Sodium chloride
  • Prefixes — di- means two and mono- means one: carbon dioxide has two oxygen atoms, carbon monoxide has one

Section 1 of 4Compounds

1Compound
= a substance in which two or more different kinds of atom are bonded together
2Bonding1 point
= the tight joining of atoms
  • Sodium atoms bonded with chlorine atoms form sodium chloride.
3Properties2 points
  • a compound has totally new properties, different from the elements it is made from
  • Sodium chloride is common salt, unlike sodium or chlorine.

Section 2 of 4Naming compounds

  • Metal first
    • if a compound contains a metal, the name of the metal comes first
  • Non-metal
    • its name is usually changed and ends in -ide: sodium chloride, not sodium chlorine
  • Prefixes
    • di- means two and mono- means one: carbon dioxide has two oxygen atoms, carbon monoxide has one
  • Oxygen compounds
    • copper sulfate contains copper, sulfur and oxygen

Section 3 of 4Particle diagrams

  • Element
    • all the atoms in a particle are the same (oxygen, O2)
  • Compound
    • different kinds of atom are bonded together (carbon dioxide CO2, water H2O, methane CH4)
  • Test
    • if different kinds of atom are bonded in the particle diagram, the substance is a compound

Section 4 of 4Formulae

  • Formula
    • contains the symbols of the elements bonded in the compound
  • Subscript number
    • the small number below and to the right of a symbol gives the number of atoms of that element; no number means one atom
NameFormulaAtoms
Calcium oxideCaO1 calcium, 1 oxygen
Carbon dioxideCO21 carbon, 2 oxygen
Carbon monoxideCO1 carbon, 1 oxygen
Hydrogen sulfideH2S2 hydrogen, 1 sulfur
Calcium carbonateCaCO31 calcium, 1 carbon, 3 oxygen
Sodium hydroxideNaOH1 sodium, 1 oxygen, 1 hydrogen
  • Care
    • do not confuse C (carbon) with Ca (calcium)

Last updated: