unit 1 questions

Question 1

Describe fully the formation of the covalent bond in hydrogen chloride in terms of orbital overlap. (3)

Answer 1

1. the half-filled 1s orbital of hydrogen and a hall-filled 3p orbital of chloride
2. overlap of the orbitals along the axis between the atoms (head-on overlap / bond formed is a sigma bond)
3. producing a region of high electron density (between the two nuclei)

1.electron configuration
2.overlap (bond type)
3.result

Question 2

Explain why the experimental and calculated values for the lattic energy of NaCl are similar whereas those for AgCl differ significantly. (3)

Answer 2

1. NaCl is (almost) 100% ionic, AgCl is partly / significantly covalent
2. large electronegativity difference between Ag and Cl (100% ionic)
3. silver ion is polarising, chloride ion is polarised by silver ion (partly covalent)

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1.conclusion
2.and3. explaination

Question 3

State what happens to the compounds present in crude oil during fractional distillation. Identify the property of the compounds which allows this process to work. (2)

Answer 3

1. The compounds evaporate / boil and condense
2. The separation depends on differences in boiling temperature