2. Atoms, elements and compounds

• Describe differences between elements, compounds and mixtures

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

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

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

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

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

• 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

2.3.1Isotopes as different atoms of the

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

2.3.2Symbols for atoms and ions

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

2.3.3Isotopes of the same element have the

• 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

2.3.4Relative atomic mass of an element

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

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

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

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

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

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

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

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

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

• 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

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

• 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

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

• Describe giant covalent structures of graphite and diamond

• 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

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

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

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

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