Answer:
Element x has an atomic number of 16, it is sulphur.
Element Y has an atomic number of 20, it is calcium.
i) Sulphur is in Group VI, period 3 in the modern periodic table,
whereas calcium is in Group II, period 4 of the modern periodic table.
ii) Ionic bonds will form between them. This is because metals and non-metals (Cacium and sulphur) usually form ionic compounds where between the ions are held by ionic bonds (which are transferred electrons so that both elements can attain a stable status).
iii) CaS
each Calcium atom can lose 2 electrons to attain 8 outermost shell electrons, while each sulphur atom can gain the 2 electrons to attain 8 outermost shell electrons, where they will most be stable (octet). Hence, the atomic ratio of Ca and S is 1:1.
