Periodicity, Group 2 and 7 Flashcards
What is the bonding in giant lattices
Metallic bonding
Why can giant lattices conduct electricity in both solids and liquids
Because it has delocalised electrons which can move
What are the bonds in simple molecular structures
London forces between molecules
Why cant simple molecular structures conduct electricity
because there are no mobile charge carriers
What is the bonding in giant lattices
Giant lattice has ionic bonding between oppositely charged ions
Why can giant lattices conduct electricity in liquids/aqueous solutions but not in solids
In solid IONS
cannot move; in solution IONS can
move.
The reactivity of the Group 2 elements Mg–Ba increases down the group.
Explain why.
The atomic radius increases so the nuclear attraction decreases and the ionisation energy decreases
Explain why the first ionisation energy of strontium is less than the first ionisation energy
of calcium.
Sr has a larger atomic radius. Sr also has an increased nuclear charge but this is outweighed by more shielding. This causes less of a nuclear attraction and lower ionisation energy.
The reaction of barium with bromine is more vigorous than the reaction of calcium with
bromine.
Explain why.
Barium has a larger atomic radius than calcium so barium has less nuclear attraction and therefore less ionisation energy needed
How are elements arranged in the periodic table
in order of increasing atomic numbers
What is meant by periodicity
The repeating trends in chemical and physical properties
Define first ionisation energy
The energy required to remove one electron from each atom in one mole of gaseous element to form one mole of gaseous 1+ ions
What factors affect ionisation energy
-atomic radius
-nuclear charge
-shielding
What is the trends in ionisation energy as you go across a period
Increase, because the nuclear charge increases as the number of protons increases thus causing an increase to the nuclear attraction. Also the atomic radius decrease so the first ionisation energy increases
State benefits of using chlorine in water treatment.
kills bacteria
State risks of using chlorine in water treatment.
-its toxic
-forms chlorinated
hydrocarbons
-forms carcinogens/toxic
compounds
What is disproportionation
when the same element is being both oxidised and reduced
Explain the trend in boiling points of the halogens.
as you go down the group the boiling point increases. this is because the number of electrons increases which makes the London forces stronger and so more energy is required to overcome the London forces
Describe and explain the reactivity going down group 7
as you go down the group reactivity decreases because atoms further down the group have a larger atomic radius and more shielding so it has less of a nuclear attraction on electrons gained
What is the trend in oxidising ability down the group 7 and why
Decrease down the group (Cl=strongest, I= weakest). This is because Cl has the fewest occupied electron shells, greatest force of attraction between outer electrons and nucleus and thus the easiest to gain electrons and be reduced
what and why is the trend in reducing ability down the halides
increases down the group (Cl =weakest, I=strongest) this is because I has the most occupied electron shell so outer electrons are further from the n nucleus, weakest force of attraction between outer electrons and positive charge of nucleus and thus is the easiest to be oxidised and loose electrons
what is the colour of chlorine in water
pale green
what is the colour of bromine in water
orange
what is the colour of iodine in water
brown
