Edexcel A level Chemistry Topic 2: questions
and answers
What is an ion? - -Ions are positively charged/negatively charged atoms.
- formed when electrons are transferred from one atom to the other.
Define an ionic bond? - -the strong electrostatic attraction between two
oppositely charged ions.
-The stronger the electrostatic attraction the stronger the bond
What two factors affect the strength of an ionic bond? - - ionic radii
- ionic charge
How does ionic radii affect the strength of the ionic bond? - - smaller ions can
pack together more closely than larger ions
- so the smaller the ion, the stronger the electrostatic attraction between ions.
- more energy is required to overcome the stronger forces.
- higher mp and bp e.g CsF has a mp of 600 whereas NaF has a mp of 1000
How does ionic charge affect the strength of an ionic bond? - - the greater the
charge, the stronger the ionic bond (electrostatic attraction) between the ions.
Due to higher charge density of ion.
,Edexcel A level Chemistry Topic 2: questions
and answers
- (bcs there's a more +ve charge on the nucleus so attracts the remaining
electrons more easily)
The strongest ionic bond is with ions that have a.......? - -high charge and small
radii
Trend in ionic radius down a group? - - increases down the group.
- same charge but an increased atomic number
- increasing number of electron shells
- therefore ionic radius increases.
What are isoelectric compounds? - - ions of different atoms with the same
number of electrons.
Trend in ionic radius of isoelectric compounds across the period? - - radius
decreases across the period.
-nuclear charge increases, but number of electron shells stays the same.
- outer electrons are attracted to the nucleus more strongly.
, Edexcel A level Chemistry Topic 2: questions
and answers
Properties of ionic compounds? - -high mp and bp
- conducts electricity when molten/dissolved
- soluble in polar solutions (water). Insoluble in non-polar solvents
- hard, brittle.
Why do ionic compounds have high mps/bps? - - strong electrostatic forces
between oppositely charged ions
- forms strong ionic bonds
- large amounts of energy required to overcome the forces, so high mp/bp.
Why do ionic compounds conduct electricity when molten, but not solid? - - in a
solid, ions can't move from their fixed position, so they cant carry a
charge/current.
- when liquid/molten, ions mobile/ free to move and can carry a charge/current.
Why are ionic compounds soluble in water, but not in non-polar solvents? - - ions
are pulled apart by polar molecules, e.g. water.
- oppositely charged ions between solvent and ionic compounds are attracted to
each other.
and answers
What is an ion? - -Ions are positively charged/negatively charged atoms.
- formed when electrons are transferred from one atom to the other.
Define an ionic bond? - -the strong electrostatic attraction between two
oppositely charged ions.
-The stronger the electrostatic attraction the stronger the bond
What two factors affect the strength of an ionic bond? - - ionic radii
- ionic charge
How does ionic radii affect the strength of the ionic bond? - - smaller ions can
pack together more closely than larger ions
- so the smaller the ion, the stronger the electrostatic attraction between ions.
- more energy is required to overcome the stronger forces.
- higher mp and bp e.g CsF has a mp of 600 whereas NaF has a mp of 1000
How does ionic charge affect the strength of an ionic bond? - - the greater the
charge, the stronger the ionic bond (electrostatic attraction) between the ions.
Due to higher charge density of ion.
,Edexcel A level Chemistry Topic 2: questions
and answers
- (bcs there's a more +ve charge on the nucleus so attracts the remaining
electrons more easily)
The strongest ionic bond is with ions that have a.......? - -high charge and small
radii
Trend in ionic radius down a group? - - increases down the group.
- same charge but an increased atomic number
- increasing number of electron shells
- therefore ionic radius increases.
What are isoelectric compounds? - - ions of different atoms with the same
number of electrons.
Trend in ionic radius of isoelectric compounds across the period? - - radius
decreases across the period.
-nuclear charge increases, but number of electron shells stays the same.
- outer electrons are attracted to the nucleus more strongly.
, Edexcel A level Chemistry Topic 2: questions
and answers
Properties of ionic compounds? - -high mp and bp
- conducts electricity when molten/dissolved
- soluble in polar solutions (water). Insoluble in non-polar solvents
- hard, brittle.
Why do ionic compounds have high mps/bps? - - strong electrostatic forces
between oppositely charged ions
- forms strong ionic bonds
- large amounts of energy required to overcome the forces, so high mp/bp.
Why do ionic compounds conduct electricity when molten, but not solid? - - in a
solid, ions can't move from their fixed position, so they cant carry a
charge/current.
- when liquid/molten, ions mobile/ free to move and can carry a charge/current.
Why are ionic compounds soluble in water, but not in non-polar solvents? - - ions
are pulled apart by polar molecules, e.g. water.
- oppositely charged ions between solvent and ionic compounds are attracted to
each other.
