Fig. 1 shows a shell model on a card used by a recycling plant to identify aluminium from its atomic structure. The plant melts aluminium cans, but workers ...
Question 1 Report
Fig. 1 shows a shell model on a card used by a recycling plant to identify aluminium from its atomic structure. The plant melts aluminium cans, but workers must avoid mixing them with other metals. The diagram gives the proton number and an electron arrangement for a neutral aluminium atom. Electrons occupy shells at different distances from the nucleus and can gain energy if an electrical discharge is applied.
(a) Calculate the mass number of the aluminium atom. [2]
(b) What is the number of electrons in the outer shell? [1]
(c) Which ion is most likely to form when aluminium loses its outer electrons? [1]
(d) Draw the electron arrangement of this aluminium ion. [2]
Answer Details
(a) The mass number is the total number of protons and neutrons in the nucleus.
\[13+14=27\]
Mass number = 27. [2]
(b) The electron arrangement shown is \(2,8,3\), so the outer shell contains 3 electrons. [1]
(c) A neutral aluminium atom loses its three outer-shell electrons. It then has three more protons than electrons, so it forms an \(\mathrm{Al^{3+}}\) ion. [1]
(d) After losing three electrons, aluminium has 10 electrons remaining. These fill the first two shells as \(2,8\); there are no electrons in a third shell. [2]
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