Answers to Data Response question on ionic bonding

Answers to ionic bonding Data response question

1. Li: 1s²2s¹, so one unpaired electron in outer energy level should be shown, but electrons in the first energy level should be shown paired.

O: 1s²2s²2p_x²2p_y¹2p_z¹, so two unpaired electrons in outer shell should be shown, but electrons in the first energy level should be shown paired.

2. The lithium atom should be shown larger than the oxygen atom. Atomic radius of Li = 0.130 nm, atomic radius of O = 0.064 nm.

3. Endothermic, +520 kJ mol^-1 (for a gaseous lithium atom)

4. It must be turned into a gas, which is an endothermic process with a value of +161 kJ mol^-1. It is known as the enthalpy of atomization (or the enthalpy of sublimation).

5. Electron affinity. Endothermic. +612 kJ mol^-1

6. It is much smaller (0.076 nm compared with 0.130 nm)

7. It is much larger (0.140 nm compared with 0.064 nm)

8. 4Li(s) + O₂(g) → 2Li₂O(s)

9. No. The oxygen molecule needs to be converted into atoms. Endothermic, +249 kJ mol^-1 (this is half the bond enthalpy)

10. [(2 x 161) + (2 x 520) + 249 + 612] = +2223 kJ mol^-1

11. The lattice enthalpy change for 2Li⁺(g) + O^2–(g) → Li₂O(s) = –596 – (+2223) = –2819 kJ mol^-1

13. Smaller. The ions are larger, and chlorine has only a single negative charge.

14.Sodium chloride has virtually 100% ionic character. Lithium oxide, although mainly ionic, possesses some covalent character. This is due to the greater charge density of the lithium ion compared with the sodium ion.

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