Atomic structure and bonding: 1.    How many electrons may be accommodated in the first three energy levels? [1]
2.    What is the same about the electron structures of:
a lithium, sodium and potassium?
b beryllium, magnesium and calcium? [2]
3.    a Define the terms: proton, neutron and electron. [3]
            b An atom X has a proton number of 19 and relative atomic mass of 39.
(i) How many electrons, protons and neutrons are there in an atom of X?
(ii) How many electrons will there be in the outer energy level (shell) of an atom of X?
(iii) What is the electronic configuration of X? [3]
4.    Draw diagrams to show the bonding in each of the following compounds:
a calcium fluoride (CaF2)
b oxygen (O2)
c magnesium chloride (MgCl2)
d tetrachloromethane (CCl4). [4]
5.    Atoms of elements X, Y and Z have 16, 17 and 19 electrons, respectively. Atoms of argon have 18 electrons.
a Determine the formulae of the compounds formed by the combination of the atoms of the elements:
(i) X and Z
(ii) Y and Z
(iii) X with itself. [3]
b In each of the cases shown in a(i)–(iii) above, name the type of chemical bond formed. [3]
c Give two properties you would expect to be shown by the compounds formed in a(ii) and a(iii). [2]
6.    The elements sodium and chlorine react together to form the compound sodium chloride, which has a giant ionic lattice structure.
a What type of structure do the elements
(i) sodium and (ii) chlorine have? [2]
b Draw a diagram to represent how the ions are arranged in the crystal lattice of sodium chloride. [2]
c Explain how the ions are held together in this crystal lattice.
d Draw diagrams to show how the electrons are arranged in a sodium ion and a chloride ion. [3]
(The proton numbers of sodium and chlorine are 11 and 17, respectively.)
e Make a table showing the properties of the three substances sodium, chlorine and sodium chloride. Include in your table:
(i) the physical state at room temperature
(ii) solubility in (or reaction with) water
(iii) colour
(iv) electrical conductivity. [12]
7.    Explain the following.
a Ammonia is a gas at room temperature.
b The melting points of sodium chloride and iodine are very different.
c Metals generally are good conductors of electricity.
d Buckminsterfullerene is an allotrope of carbon.
e Graphite conducts electricity but diamond does not. [5]

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