Paper 2 · June 2024 · Atomic Structure and Bonding

An ion X has 8 protons, 8 neutrons and a charge of 2-. An ion Y has 13 protons, 14 neutrons and a charge of 3+. State the formula of the compound formed when X and Y combine.

Model answer

Al2O3

Also accepted: aluminium oxide

Explanation

X has proton number 8 (oxygen), so the 2- ion is the oxide ion O2-. Y has proton number 13 (aluminium), so the 3+ ion is Al3+. Two Al3+ ions balance three O2- ions in charge, giving Al2O3.

Derived from ZIMSEC Chemistry 4024/2, June 2024, Q1(a)(i)

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