2A - Electrons - review

    1)    Define the term first ionisation energy.  [3]

    2)    Electrons are arranged in energy levels.

        (a)     An orbital is a region in which an electron may be found.  Draw diagrams to show the shape of an s orbital and of a p orbital.  [2]

        (b)     Complete the table below to show how many electrons completely fill each of the following.  [3]


number of electrons

a d orbital


a p sub-shell


the third shell (n = 3)


    3)    The energy diagram below is for the eight electrons in an oxygen atom. The diagram is incomplete as it only shows the two electrons in the 1s level.

                 Complete the diagram for the oxygen atom by:

          (a)      adding labels for the other sub-shell levels,  [1]

          (b)     adding arrows to show how the other electrons are arranged.  [1]


4)    The table shows the first 6 successive ionisation energies of an element X, which is in Period 3 of the Periodic Table.

        Use the table to identify element X. Explain how you decided on your answer.  [3]


ionisation energy / kJ mol1












11 578

14 831

18 378


    5)    (a)      Write an equation, with state symbols, to represent the second ionisation energy of calcium.  [2]

           (b)      Why is the second ionisation energy of calcium greater than their first ionisation energies?  [1]

           (c)     Explain why the first ionisation energy of strontium are less than that of calcium.  [3]

    6)    The electronic configuration of a bromine atom can be written in terms of sub-shells.

        (a)      Complete the electronic configuration of a bromine atom.  [2]

                    1s22s22p63s23p6 ...............

        (b)      Why is bromine classified as a p-block element?  [1]

        (c)    Write the electron configuration for a bromine ion  [1]

                    1s22s22p63s23p6 ...............