Question

18.

The bonding in calcium nitrate is ionic, with Ca²+ and NO₂ ions present.
Using a diagram, or otherwise, explain how the ions interact with water when
forming a solution.
[2]
17.
(a) Explain the term electronegativity.
(b) The table gives some electronegativity values.
Atom
Electronegativity
Al
1-61
Be
1-57
H Mg
2-20 1-31
N
S
3.04 2-59
[1]
Select the two atoms from the list which would give the most polar bond when
[1]
combined.

Answer 1

18

When calcium nitrate dissolves in water, the ionic bonds between the Ca²+ and NO₂ ions are broken due to the polarity of water molecules. The oxygen atoms of the water molecules have a partial negative charge while the hydrogen atoms have a partial positive charge. When Ca²+ ions are surrounded by water molecules, the partial negative charges on the oxygen atoms of water molecules interact with the positively charged Ca²+ ions through electrostatic attraction, forming a hydrated Ca²+ ion. Similarly, the partial positive charges on the hydrogen atoms of water molecules interact with the negatively charged NO₂ ions, forming hydrated NO₂ ions. The resulting solution consists of hydrated Ca²+ and NO₂ ions, dispersed evenly throughout the water.

17

(a) Electronegativity is a measure of an atom's ability to attract electrons towards itself when it is bonded to another atom. It is a relative scale, with the most electronegative element, fluorine, assigned a value of 4.0.

(b) The two atoms that would give the most polar bond when combined are Al and N. This is because they have the largest difference in electronegativity values, which is a measure of the polarity of a bond. The electronegativity difference between Al and N is 1.43, which is larger than any other combination of atoms given in the table