3. Atoms, elements and compounds

3. Atoms, elements and compounds

1. 3.1 Atomic structure and the Periodic Table

   • state the relative charges and approximate relative masses of protons, neutrons and electrons
   • define proton number (atomic number) as
     • the number of protons in the nucleus of an atom
   • define nucleon number (mass number) as
     • the total number of protons and neutrons in the nucleus of an atom
   • use proton number and the simple structure of atoms to explain the basis of the Periodic Table (See section 9)
     • with special reference to the elements of proton number 1 to 20
   • define isotopes as
     • atoms of the same element which have the same proton number but a different nucleon number
   • understand that isotopes have the same properties because they have the same number of electrons n their outer shell
   • state the two types of isotopes as being
     • radioactive
       • state one medical use
       • state one industrial use
     • non-radioactive
   • describe the build-up of electrons in 'shells'
     • and understand the significance of the noble gas electronic structures and of the outer shell electrons
       • the ideas of the distribution of electrons in s and p orbitals and in d block elements are not required)
   • NOTE: a copy of the Periodic Table, as shown in the Appendix, will be available in Papers 1,2,3 and 4

2. 3.2 Structure and bonding

   • 3.2.1 Bonding: the structure of matter
     • describe the differences between
       • elements, mixtures and compounds
       • metals and non-metals
     • describe an alloy, such as brass, as
       • a mixture of a metal with other elements
   • 3.2.2 Ions and ionic bonds
     • describe the formation of ions by electron loss or gain
     • describe the formation of ionic bonds between metallic and non-metallic elements
     • describe the formation of ionic bonds between elements from Groups I and VII
     • describe the lattice structure of ionic compounds as
       • a regular arrangement of alternating positive and negative ions
   • 3.2.3 Molecules and covalent bonds
     • describe the formation of single covalent bonds in H2, Cl2, H2O, CH4, NH3 and HCl
       • as the sharing of pairs of electrons leading to the noble gas configuration
     • describe the electron arrangement in more complex covalent molecules such as N2, C2H4, CH3OH an CO2
     • describe the difference in volatility, solubility and electrical conductivity between ionic and covalent compounds
     • explain the differences in melting point and boiling point of ionic and covalent compounds in terms of attractive forces
   • 3.2.4 Macromolecules
     • describe the giant covalent structure of graphite and diamond
       • relate their structure to their uses e.g.
         • graphite as a lubricant and a conductor
         • diamond in cutting tools
     • describe the macromolecular structure of silicon(IV)oxide (silicon dioxide)
       • describe the similarity in properties between diamond and silicon(IV)oxide, related to their structures
   • 3.2.5 Metallic bonding
     • describe metallic bonding as
       • a lattice of positive ions in a 'sea of electrons' and use this to describe the electrical conductivity and malleability of metals