(a)(i) Mention two types of bond present in the ammonium ion
(ii) Give three characteristic properties of electrovalent compounds
(iii) State. two differences between chemical reactions and nuclear reactions
(b) Two elements represented by the letters and Y have atomic numbers 9 and 12 respectively.
(i) Write the electronic configuration of X using the s,p,d, notation
(ii) To what group does Y belong in the periodic table?
(iii) Write the formula of the compound formed when X copibines with Y
(iv) Explain wily X is a good oxidizing agent
(v) State with reason, whether Y would be expected to form acidic or basic oxide
(c) Balance the following nuclear equations and identify the particles represented by X and Y.
(i) \(^{14}_6C\) \(\to\) X + \(^{14}_7N\)
(ii) \(^{14}_7C\)
Y \(\to\) \(^1_1H\) + \(^{17}_8O\)
(d) Consider the following list of substances: Carbon (IV) oxide, hydrogen, zinc, sulphier, methane, potassium and mercury. From the list above, state the:
(i) elements that are metals
(ii) compounds that are gases at room temperature
(iii) non-metals that are solids at room temperature
(a)(i) The ammonium ion contains a covalent bond and a coordinate (dative) bond.
(ii) Three properties of electrovalent compounds: high melting and boiling points; conduct electricity when molten or in aqueous solution; soluble in water (polar solvents); exist as hard crystalline solids.
(iii) Differences between chemical and nuclear reactions:
- A chemical reaction involves only the outer electrons (rearrangement of atoms); a nuclear reaction involves changes in the nucleus (protons and neutrons).
- A chemical reaction forms no new element; a nuclear reaction forms new elements or isotopes and releases far more energy.
(b) X (Z = 9) is fluorine; Y (Z = 12) is magnesium.
(i) X: \(1s^2 2s^2 2p^5\).
(ii) Y belongs to Group II.
(iii) Compound of X with Y: MgF2.
(iv) X (fluorine) is a good oxidizing agent because it readily gains one electron to complete its octet, owing to its small size and high effective nuclear charge (high electronegativity); in doing so it oxidizes other species.
(v) Y is a metal (electropositive), so it forms a basic oxide (MgO), as metallic oxides are basic.
(c)(i) \(^{14}_{6}C \rightarrow X + ^{14}_{7}N\): mass \(14 = 14 + A\) so A = 0; charge \(6 = 7 + Z\) so Z = -1. X = \(^{0}_{-1}e\) (a beta particle).
(ii) \(^{14}_{7}N + Y \rightarrow ^{1}_{1}H + ^{17}_{8}O\): mass \(14 + A = 18\) so A = 4; charge \(7 + Z = 9\) so Z = 2. Y = \(^{4}_{2}He\) (an alpha particle).
(d) From the list:
- (i) Metals: zinc, potassium, mercury.
- (ii) Compounds that are gases at room temperature: carbon(IV) oxide and methane.
- (iii) Non-metals that are solids at room temperature: sulphur.
(a)(i) The ammonium ion contains a covalent bond and a coordinate (dative) bond.
(ii) Three properties of electrovalent compounds: high melting and boiling points; conduct electricity when molten or in aqueous solution; soluble in water (polar solvents); exist as hard crystalline solids.
(iii) Differences between chemical and nuclear reactions:
- A chemical reaction involves only the outer electrons (rearrangement of atoms); a nuclear reaction involves changes in the nucleus (protons and neutrons).
- A chemical reaction forms no new element; a nuclear reaction forms new elements or isotopes and releases far more energy.
(b) X (Z = 9) is fluorine; Y (Z = 12) is magnesium.
(i) X: \(1s^2 2s^2 2p^5\).
(ii) Y belongs to Group II.
(iii) Compound of X with Y: MgF2.
(iv) X (fluorine) is a good oxidizing agent because it readily gains one electron to complete its octet, owing to its small size and high effective nuclear charge (high electronegativity); in doing so it oxidizes other species.
(v) Y is a metal (electropositive), so it forms a basic oxide (MgO), as metallic oxides are basic.
(c)(i) \(^{14}_{6}C \rightarrow X + ^{14}_{7}N\): mass \(14 = 14 + A\) so A = 0; charge \(6 = 7 + Z\) so Z = -1. X = \(^{0}_{-1}e\) (a beta particle).
(ii) \(^{14}_{7}N + Y \rightarrow ^{1}_{1}H + ^{17}_{8}O\): mass \(14 + A = 18\) so A = 4; charge \(7 + Z = 9\) so Z = 2. Y = \(^{4}_{2}He\) (an alpha particle).
(d) From the list:
- (i) Metals: zinc, potassium, mercury.
- (ii) Compounds that are gases at room temperature: carbon(IV) oxide and methane.
- (iii) Non-metals that are solids at room temperature: sulphur.
