Reactivity trends

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Total cards: 24•Content version: v4•Public deck•Updated: 8/1/2026

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Front (Question)

what happens to reactivity down group 2?

Back (Answer)

reactivity increases

Front (Question)

what reactions do group 2 elements undergo? (and products)

Back (Answer)

redox with: - oxygen (metal oxide) - water (metal hydroxide + H2) - acid (salt + H2)

Front (Question)

what happens to ionisation energy down group 2?

Back (Answer)

IE decreases

Front (Question)

what observations would be made when group 2 reacts with water?

Back (Answer)

• increase in pH (shown by indicator) • solid precipitate once the solution becomes saturated (group 2 hydroxide are sparingly soluble)

Front (Question)

what happens to solubility down group 2 hydroxides? and what effect does this have on pH?

Back (Answer)

solubility increases which increases [OH-] so increases pH

Front (Question)

uses of group 2 compounds

Back (Answer)

• Ca(OH)2 used in agriculture (as lime) to increase pH of acidic soils (producing water) • Mg(OH)2 or CaCO3 used in antacids (treating acid indigestion) by neurtalising HCl/stomach acid

Front (Question)

what happens to boiling point down group 7?

Back (Answer)

boiling point increases (more e-, stronger LDFs)

Front (Question)

chlorine state and colour (RTP)

Back (Answer)

pale green gas

Front (Question)

bromine state and colour (RTP)

Back (Answer)

red-brown liquid with orange vapour

#10

Front (Question)

iodine state and colour (RTP)

Back (Answer)

solid grey-black crystals

#11

Front (Question)

what reactions do halogens undergo?

Back (Answer)

• redox • halogen-halide displacement

#12

Front (Question)

what happens in halogen-halide displacement?

Back (Answer)

more reactive halogen displaces the halide from solution (causes colour change)

#13

Front (Question)

reaction and colour change when I-(aq) is mixed with Cl2(aq)

Back (Answer)

2I- + Cl2 –> I2 + 2Cl- pale green to violet

#14

Front (Question)

colours of Cl2, Br2, I2 in water

Back (Answer)

Cl2 - pale green Br2 - orange I2 - brown

#15

Front (Question)

colours of Cl2, Br2, I2 in cyclohexane

Back (Answer)

Cl2 - pale green Br2 - orange I2 - violet

#16

Front (Question)

how can you tell apart solutions of iodine and bromine in water?

Back (Answer)

• add cyclohexane and shake mixture • halogens will dissolve more readily • colours will be more obvious

#17

Front (Question)

fluorine state and colour

Back (Answer)

pale yellow gas

#18

Front (Question)

disproportionation

Back (Answer)

redox reaction in which the same element is both oxidised and reduced

#19

Front (Question)

two examples of disproportionation

Back (Answer)

• Cl2 + H2O • Cl2 + NaOH

#20

Front (Question)

how is Cl used in disinfectant and water sterilisation?

Back (Answer)

chlorate, ClO- ions kill bacteria

#21

Front (Question)

how can you demonstrate ClO- acting as bleach?

Back (Answer)

• mix Cl2 + H2O • add indicator • indicator will turn red (HCl and HClO are acidic) then colour will disappear as it is bleached

#22

Front (Question)

why would use dissolve NaOH in water before adding Cl2?

Back (Answer)

• Cl2 is sparingly soluble in water • more Cl2 dissolves in the presence of NaOH • Cl2 reacts with NaOH in a disproportionation reaction to form ClO-

#23

Front (Question)

risks of chlorine use

Back (Answer)

• Cl2 reacts with organic hydrocarbons such as methane from decaying vegetation • this forms chlorinated hydrocarbons which are suspected carcinogens

#24

Front (Question)

benefits of chlorine use

Back (Answer)

• prevent outbreaks of waterborne diseases like typhoid and cholera