Question 1
Paper 2Hard8 marksA chemistry student uses the metallic model to explain properties of lithium and to assess claims about Group 1 metals. Figure 1 shows a simplified model of lithium before and during shear. The table gives first ionization energies.
| Element | First ionization energy / kJ mol⁻¹ |
|---|---|
| Li | 520 |
| Na | 496 |
| K | 419 |
A student argues: “The decrease in first ionization energy from Li to K explains the increase in Group 1 reactivity. It also proves that metallic bonding becomes stronger, so potassium must conduct electricity better than lithium.”
State the nature of the metallic bond in terms of the particles involved.
Use Figure 1 to explain how the metallic model accounts for malleability.
Explain how the metallic model accounts for electrical conductivity.
Evaluate both inferences made by the student, using Figure 1 and the table.