(a)(i) Determine the maximum number of electrons that can occupy the principal energy level M of an atom.
(ii) Show the changes in the electronic structures of atoms of sodium and fluorine ((^{23}_{11})Na: (^{19}_{9}F)) when they combine to form sodium fluoride.
(iii) State: three properties that sodium fluoride would have, based a-n the bond type present in the compound.
(b) Write equations to show when:
(i) sodium metal burns in limited supply of oxygen;
(ii) water is added to the product in (b)(i) above
(c) Describe a suitable laboratory procedure for comparing the conductance of 1 mol dm(^{-3}) aqueous solutions of sodium hydroxide and ethanoic acid.
Explanation
(a)(i) For M, n = 3. Substituting into 2n(^2), 2 x 3 x 3 = 18 is obtained.
(ii)
| Befor Combination | after Combination |
|
Sodium 1s(^2)2s(^2)2p(^6)3s(^1) (Na) Fluorine 1s(^2)2s(^{2})2p(^5) (F) |
s(^2)2s(^2)2p(^6) (Na(^+)) 1s(^2)2s(^2)2p(^6) (F(^-)) |
(iii) (1) High melting and high boiling points.
(2) Conduction of electricity in solution
(3) Solubility in water
(b) 4Na + O(_2) -> 2Na(_2)O
Na(_2)O + H(_2)O -> 2NaOH
(c) Place 100cm(^3) of each (or equal volumes) in separate identical beakers and connect as shown in the diagram below.
Record the ammeter reading using one solution as the test solution. Using one solution as the test solution, connect again as shown in the diagram and take the reading. The higher reading indicates the electrolyte which has the higher conductance.