Group 7 - Topic 6 Flashcards

Question

Colour of iodine in water:

Answer 1

orange/brown

Answer 2

- mp = 302 degrees C - bp = 337 degrees C

Answer 3

- elements in Group 7 form diatomic molecules - covalent bonds between halogen atoms

Answer 4

- diatomic - simple covalent - mp and bp increase as you go down Group 7

Answer 5

- There is a trend in state from gas to liquid to solid down the group - this is because the melting and boiling points increase as you go down the group - from this, you can predict that any halogens above chlorine will be gases (their boiling points will be even lower), and any below iodine will be solids (their melting points will be even greater)

Answer 6

- the bonds within the molecules get weaker due to the larger distance between the nucleas and the shared pair of electrons due to their being more shells but these bonds don’t break during melting - the intermolecular forces gets stronger as you go down Group 1, so more energy is needed to overcome them and melt the halogen

Answer 7

- When damp litmus paper is put into where the chlorine gas is suspected to be the litmus paper is bleached and turns white as chlorine is a bleaching agent - litmus paper has to be damp so the water can react with the chloride - if it isn't damp it will set on fire

Answer 8

1. Some Cl reacts with water (on damp litmus paper) to form acids HCl and HOCl products change litmus paper to red (acid turns paper red) 2. Some chlorine gas (Cl2) is dissolved which bleaches the litmus paper and turns it white as chlorine is a bleaching agent

Answer 9

compound formed when halogens react with metals and non-metals

Answer 10

- Compounds called halides - They react with metals to form ionic compounds in which the halide ion carries a -1 charge. e.g. NaCl or MgBr2 (as Mg has a +2 charge so you need two Br- to cancel this out) - Direct combination reaction as 2 elements combine to form a compound e.g. aluminium + chlorine ——> Aluminium chloride

Answer 11

- compounds called halides - bonding between these elements is covalent

Answer 12

- halogen + hydrogen → hydrogen halide (HCl, HBr, HI) - reaction becomes less vigorous down group: chlorine reacts in sunlight, but bromine will react in a flame (higher temperature) - hydrogen halides dissolve in water to produce acidic solutions- in solution the hydrogen halide will fully dissociate into H+ and halide- ions

Answer 13

- Astatine (At) —> Iodine (I) —> Bromine (Br) —> Chlorine (Cl) —> Fluorine (F)

Answer 14

- reactivity of halogens increases as you go up group 7 - halogens form negative ions when they react - halogens need to gain an electron to gain a full outer shell when they react - as you go down Group 7, there atoms become larger due to there being a greater number of shells - so there larger distance/gap between the positive nucleus and the outer shell electrons due to increased electron shielding/the outer shell electron being further from the nucleus due to there being more shells - therefore, there is a weaker force of nuclear attraction from the nucleus and incoming electrons/outer shell electrons to fill the outer shell so the halogen to gain a full outer shell - so as you go down Group 7 the outer shell gains an electron less easily - as you go down the Group 7, the reactivity of halogens decreases - the halogens react by gaining an electron in their outer shell, as you go down the group: - outer shell becomes further from the nucleus - electron shielding causes attraction to decrease between nucleus and outer electrons - electrons are gained less easily - halogens become less reactive

Answer 15

- reactivity increases as you go down Group 1 - as negative outer shell electrons get further away from the nucleus so attraction between nucleus and outer shell electrons decreases allowing the metal atom to lose electrons and gain a full outer shell

Answer 16

- A more reactive halogen can displace a less reactive in an aqueous solution of its salt. - E.g. Chlorine will displace bromine if we bubble the gas through a solution of potassium bromide: - chlorine + potassium bromide —> potassium chloride + bromine

Answer 17

- More reactive halogen which displaces the less reactive one from the compound, forms a negative ion itself, therefore being reduced as it has gained electrons - The less reactive halogen that is displaced is oxidised as it gains these electrons to go from a negative ion to an atom with 0 charge

Answer 18

1. Covalent molecules don’t split up when they dissolve in water e.g. a Br2 (aq) molecule is the same as a Br2 (I) molecule 2. Soluble ionic compounds split up when they dissolve in water e.g. NaCl (s) —> NaCl (aq) is really Na+ (aq) + Cl- (aq)

Answer 19

oxidation is loss, reduction is gain (of electrons)

Answer 20

- because an element has been reduced and an element has been oxidised

Answer 21

- halogen atoms gain an electron to obtain a full outer shell like a noble gas - the nearer the outer shell is to the nucleus, the stronger the attraction for the incoming electron and so the more reactive the halogen is - as you go down group 7 the size of the atoms becomes larger and the further the nucleus is from the outer shell - this means that the attraction for the incoming electron and the nucleus becomes weaker and the halogens get less reactive towards the bottom of the group

Answer 22

- halides formed by hydrogen atoms when they gain an electron - have a 1- charge

Answer 23

- a reaction involving the gain of oxygen - the loss of electrons

Answer 24

- reaction involving the loss of oxygen - gain of electrons

Answer 25

a chemical reaction in which oxidation nd reduction occur simultaneously

Answer 26

- OILRIG - more reactive halogen displaces less reactive one - forms a negative ion itself, therefore, being reduced as it has gained electrons - less reactive halogen that is displaced is oxidised as it loses these electrons to go from a negative ion to an atom with 0 charge - E.g. for the equation: chlorine + potassium bromide ——> potassium chloride + bromine - the symbol eqn without potassium is: Cl₂ + 2Br⁻ ——> 2Cl⁻ + Br₂ - so for chorine the half equation is: Cl₂ + 2e⁻ ——> 2Cl⁻, chlorine has gained electrons so has been reduced - for bromine the half eqn is: 2Br⁻ ——> Br₂ + 2e⁻, bromine has lost electrons so it has been oxidised

Group 7 - Topic 6 Flashcards

(54 cards)