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2. Atoms, elements and compounds

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  1. 2.1 Elements, compounds and mixtures

    1. • Describe differences between elements, compounds and mixtures

  2. 2.2 Atomic structure and the Periodic Table

    1. • Describe structure of the atom as a central nucleus containing neutrons and protons surrounded by electrons in shells

    2. • State the relative charges and relative masses of a proton, a neutron and an electron

    3. • Define proton number/atomic number as the number of protons in the nucleus of an atom

    4. • Define mass number/nucleon number as the total number of protons and neutrons in the nucleus of an atom

    5. • Determine the electronic configuration of elements and their ions with proton number 1 to 20, e.g. 2,8,3

    6. • State periodic table shell rules: (a) Group VIII noble gases have full outer shells (b) outer-shell electrons equal group number in Groups I-VII (c) occupied shells equal period number

  3. 2.3 Isotopes

    1. • Define isotopes as different atoms of the same element that have the same number of protons but different numbers of neutrons

    2. • Interpret/use symbols for atoms and ions, e.g. 12C and 35Cl- notation with mass/nucleon and proton/atomic numbers

    3. • State: isotopes of the same element have the same chemical properties because they have the same number of electrons and therefore the same electronic configuration

    4. • Calculate the relative atomic mass of an element from the relative masses and abundances of its isotopes

  4. 2.4 Ions and ionic bonds

    1. • Describe formation of positive ions, known as cations, and negative ions, known as anions

    2. • State: an ionic bond is a strong electrostatic attraction between oppositely charged ions

    3. • Describe formation of ionic bonds between elements from Group I and Group VII, including the use of dot-and-cross diagrams

    4. • Describe properties of ionic compounds: (a) high melting points and boiling points (b) good electrical conductivity when aqueous or molten and poor when solid

    5. • Describe giant lattice structure of ionic compounds as a regular arrangement of alternating positive and negative ions

    6. • Describe formation of ionic bonds between ions of metallic and non-metallic elements, including the use of dot-and-cross diagrams

    7. • Explain ionic compound properties from structure/bonding: high melting/boiling points and electrical conductivity when molten or aqueous, but not solid

  5. 2.5 Simple molecules and covalent bonds

    1. • State: a covalent bond is formed when a pair of electrons is shared between two atoms leading to noble gas electronic configurations

    2. • Describe formation of covalent bonds in simple molecules, including H2, Cl2, H2O, CH4, NH3 and HCl. Use dot-and-cross diagrams to show the electronic configurations in these and similar molecules

    3. • Describe simple molecular compound properties from structure/bonding: low melting/boiling points and poor electrical conductivity

    4. • Describe formation of covalent bonds in simple molecules, including CH3OH, C2H4, O2, CO2 and N2. Use dot-and-cross diagrams to show the electronic configurations in these and similar molecules

    5. • Explain simple molecular compound properties: low melting/boiling points due to weak intermolecular forces, and poor electrical conductivity

  6. 2.6 Giant covalent structures

    1. 2.6.1Giant covalent structures of graphite

      • Describe giant covalent structures of graphite and diamond

    2. 2.6.2Relate the structures and bonding of

      • Relate the structures and bonding of graphite and diamond to their uses, (a) graphite as a lubricant and as an electrode (b) diamond in cutting tools

    3. 2.6.3Giant covalent structure of

      • Describe giant covalent structure of silicon(IV) oxide, SiO2

    4. 2.6.4Similarity in properties between

      • Describe similarity in properties between diamond and silicon(IV) oxide, related to their structures

  7. 2.7 Metallic bonding

    1. • Describe metallic bonding as the electrostatic attraction between the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons

    2. • Explain metallic properties from structure/bonding: good electrical conductivity, malleability and ductility