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1. Elements and compounds can exist as diatomic molecules - Scottish Highers Chemistry - Question 1 - 2022
Question 1
1. Elements and compounds can exist as diatomic molecules. (a) The seven elements that exist as diatomic molecules are shown in the periodic table below. (i) Expla... show full transcript
Worked Solution & Example Answer:1. Elements and compounds can exist as diatomic molecules - Scottish Highers Chemistry - Question 1 - 2022
Step 1
Explain why diatomic elements form non-polar molecules.
Answer
Diatomic elements, such as H₂ and O₂, consist of two identical atoms that share electrons equally. Because the atoms have the same electronegativity, there is no charge separation in the molecule, resulting in a non-polar bond.
Step 2
Explain the decrease in covalent radius going from nitrogen to fluorine.
Answer
As you move from nitrogen to fluorine, the number of protons in the nucleus increases, leading to a stronger electrostatic attraction between the nucleus and the bonding electrons. This results in a decrease in the covalent radius because the electrons are pulled closer to the nucleus.
Step 3
Step 4
Explain why the first ionisation energy of the group 7 elements decreases going down the group.
Answer
The first ionisation energy decreases down group 7 due to two main factors: an increase in atomic size and the presence of additional electron shells. The larger atomic radius means that the outer electrons are further from the nucleus, and the increased shielding effect of inner electrons reduces the effective nuclear charge experienced by the outermost electrons, making them easier to remove.
Step 5
State the name of the strongest type of intermolecular force found between hydrogen fluoride molecules and explain how this type of intermolecular force arises.
Answer
The strongest type of intermolecular force in hydrogen fluoride (HF) is hydrogen bonding. This occurs because the hydrogen atom is covalently bonded to a highly electronegative atom (fluorine), causing the hydrogen to develop a partial positive charge and the fluorine to develop a partial negative charge, resulting in attractive interactions between the molecules.
Step 6
Explain fully why the boiling point increases from hydrogen chloride to hydrogen iodide.
Answer
The increase in boiling point from hydrogen chloride (HCl) to hydrogen iodide (HI) can be attributed to two main factors: the increase in molecular size and the resulting increase in London dispersion forces. As the molecular weight increases, there are more electrons that can create temporary dipoles, leading to stronger London dispersion forces. Additionally, HI has a larger atomic radius than HCl, which contributes to higher boiling points.