Fig. 1 shows a dot-and-cross diagram for hydrogen chloride gas collected during the manufacture of swimming-pool chemicals. The outer-shell electrons are sh...
Question 1 Report
Fig. 1 shows a dot-and-cross diagram for hydrogen chloride gas collected during the manufacture of swimming-pool chemicals. The outer-shell electrons are shown only.
(a) Complete the formula of hydrogen chloride: H___ [1]
(b) Name the bond in Fig. 1. [1]
(c) Give the number of shared electrons in the bond. [1]
(d) Suggest why hydrogen chloride gas has a much lower melting point than sodium chloride. [1]
The diagram shows electron transfer when sodium reacts with chlorine to make salt for a food factory. Crosses are electrons from sodium and dots are electrons from chlorine.
(a) Complete the ion formed from sodium: Na___ [1]
(b) What happens to the outer electron of sodium? [1]
(c) Name the ion formed from chlorine. [1]
(d) Suggest why sodium chloride has a high melting point. [1]
Answer Details
Hydrogen chloride
- (a) The formula is HCl. [1]
- (b) The bond is covalent. [1]
- (c) There are 2 shared electrons in one covalent bond. [1]
- (d) Hydrogen chloride has a much lower melting point than sodium chloride because it has weak forces between small molecules rather than strong ionic attractions. [1]
Sodium chloride formation
- (a) The sodium ion is Na+. [1]
- (b) Sodium's outer electron is transferred to chlorine. [1]
- (c) Chlorine forms a chloride ion. [1]
- (d) Sodium chloride has a high melting point because strong electrostatic attractions between oppositely charged ions need much energy to overcome. [1]
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