Group 2 & Group 7

Question 1

Group 1 & Group 2 have the same trends

Question 2

Atomic Radius

Answer 2

• Down G2, INCREASES
  ↳ more QL = more electrons →electrons are further away : easier to remove

Question 3

Ionisation Energy

Answer 3

• Down G2, DECREASES
  ↳ more QL = further away electrons →easier to remove : less energy needed

Question 4

Mp/Bp

Answer 4

• Down G2, DECREASES
  ↳ atomic radius increases = outershell has lower nuclear charge (between cation & electron)
  ↳ less energy is needed to break this making the mp/bp lower

Question 5

Reactivity to water

Answer 5

• Down G2, increases
  ↳ atomic radius increases = outer electron is further away
  ↳ reacts w water easily

Question 6

G2 react w water produce HYDROXIDES

Answer 6

Question 7

G2 burn in oxygen forming OXIDES

Answer 7

Question 8

G2 react w chlorine forming CHLORIDES

Answer 8

Question 9

Trend

Answer 9

Every G2 elements form ionic bonds except Berilium which forms covalently
* BeO doesn’t react w water (exception)
* MgO reacts slowly w water

Question 10

Down G2, reactivity increases

Answer 10

• Alkaline solutions become stronger
  ↳ the hydroxide ions become more soluble
  -hydeoxides form more quickle : the pH of the solution goes above 7

Question 11

G2 Oxides react w water

Answer 11

Question 12

G2 Oxides react w dilute acid

Answer 12

Question 13

Solubility Trend

Hydroxide

Answer 13

Down G2, increases in hydroxide ions (OH)
* more soluble : pH goes above seven
↳ meaning that it will dissolve faster

Question 14

Solubility Trend

Sulfate

Answer 14

Down G2, decreases in sulfate ions (SOv4 -2)
* become less soluble
↳ dissolve slower

Question 15

Thermal Stability

Answer 15

Applied heat needed to break something down

Question 16

Large ions are Destabilised/Polarised/Distorted by cations

Carbonates/Nitrates

Answer 16

They’re broken down by negative ions

Question 17

Thermal Stability

Trend 1)

Answer 17

Greather distortion = more unstable the compound

Question 18

Thermal Stability

Trend 2)

Answer 18

Larger cations = smaller distortion than small cations
↳lower charge density

-down G2 atomic radius increases
↳ electrons = further away & ion can’t hold onto them
↳ if it can’t even do this, then it can’t pull another’s electrons

Question 19

Charge Density

Charge per space/ Charge over smaller space

Answer 19

Larger cation = lower CD
↳ less distortion = more stable the nitrate/carbonate compound

Question 20

Top G2 = most polarising

Smaller atomic radius = more polarising
Higher charge = more polarising

Answer 20

G2 cations have a 2+ charge compared to a +1 from G1 so G2 carbonates/nitrates = less stable than G1

Question 21

Anions

Thermal Stability Testing

Nitrate Decomposition

Answer 21

• Test to see how long it takes for a certain amount of O2 to be released

Glowing splint relights if positive

• Test to see how long it takes for NO2 to form

NO2 gas is brown

Question 22

Anion

Thermal Stability Testing

Carbonate Decomposition

Answer 22

• Test to see how long it takes for a certain amount of CO2 t be released

Limewater goes cloudy if positive

Question 23

Cation

Flame Test

Equipment

Answer 23

• HCl
• Metal solutions (cations)
• Nichrome wire
• Bunsen Burner

Question 24

Cation

Flame Test

Practical done because some metals have the same colour

Answer 24

1. Take nichrome wire & dip into HCl
2. Put that wire into flame
   ↳ step 1 & 2 cleans loop
3. Dip wire into one of the metal solutions
4. Place that wire into the flame at 45° just below top of the flame for 5 secs
5. Observe colour & note it down
6. Repeat 1-8 until you’re done w all solutions
7. Repeat procedure again for each solution
   ↳ some reactions occur quickly : recheck colour

!!If all tests are orange, your test is contaminated!!

Question 25

Colours of metal ions

Answer 25

***G1*** * Li+ = red * Na+ = yellow/orange * K+ = lilac * Rb+ = red **G2** * Ca2+ = red * Sr2+ = crimson red * Ba2+ = green **neither** * Cu2+ = blue/green

Question 26

Down G7 = **less reactive** | As they're reduced, they oxidise another substance (oxiding agents)

Answer 26

* Larger G7 atoms are less reactive **:** reactivity decreases down the group (electronegativity) ↳ due to increase in QL

Question 27

Down G7 = **Mp/Bp increase**

Answer 27

**Mp** Down G7, states change ↳ more energy is needed to break bonds **Bp** Down G7, there are more QL **:** more electrons ↳ more London Forces ↳ more energy needed to break these

Question 28

Group 7 Properties Table

Answer 28

Question 29

G7 Properties by theirselves

Answer 29

* Diatomic * Non-polar ↳ can't form ions **:** they can't carry a charge **:** can't conduct electricity or dissolve in water ↳ but can dissolve in organic compounds i.e. **HEXANE**

Question 30

G7 Colours

Answer 30

Question 31

Halide

Answer 31

Charged halogen

Question 32

Displacement

Answer 32

Where an element replaces another in a compound

Question 33

Halogens can displace halide ions from solutions

Answer 33

The more reactive the halogen, the more able it is to displace a less reactive halide ↳ they have a higher oxidation strength * The colour expressed within the solution = the colour of the uncombined halide

Question 34

Halogens can react w G1 & G2 metals

Answer 34

Question 35

Disproportionation w Cold Alkali | Sodium Hydroxide

Answer 35

g + aq → aq + aq + l

Question 36

Disproportionation w Cold Alkali Example | Chlorine & Sodium Hydoxide

Answer 36

* Make bleach ↳ bleach is used in water treatment & textiles

Question 37

Disproportionation w Hot Alkalis

Answer 37

g + aq → aq + aq + l

Question 38

**HALIDES** lose electrons if there's less of a pull from nucleus & outer electron is weak

Question 39

Down G7 = **attraction weaker**

Answer 39

* Atomic radius increases **:** electrons are further away ↳ there's more shielding from inner electrons

Question 40

All halides react w CONCENTRATED sulfuric acid to give a hydrogen halide

Answer 40

Concentrated Sulfuric Acid = always liquid

Question 41

Reaction of KF/KCl w H2SO4

Answer 41

* Oxidation number for Sulfur doesn't change ↳ F- & Cl- ions aren't strong enough reducing agents to reduce Sulfur's oxidation number * This reaction isnt redox as the oxidation number of the halide & sulfur remain the same * Produce misty fumes

Question 42

Reaction of KBr w H2SO4

Answer 42

* 2nd reaction occurs instantly after 1st * HBr dissolves in the solution bc it isn't isolated * HBr produces mistry fumes Br gives its electron more easily to S & drops S down to ox. no° 4 ↳Br is a stronger reducing agent than Cl- & F- bc it has more electrons ↳ this is redox reaction as ox. no° change

Question 43

Reaction of KI w H2SO4

Answer 43

* 3 reactions 1. 1st reaction occurs 2. 2nd reaction occurs instantly after 3. 1st reaction isn't stopped **:** reoccurs 4. 3rd reaction produced slightly after

Question 44

Summary | Strength of reducing agents increases → causing S ox. number to decrease

Answer 44

**Flourine/Chloride** +6 → +6 **Bromide** +6 → +4 **Iodide** +6 → +4 -2

Question 45

Test for Halides

Answer 45

* Add nitric acid ↳ removes interface ions * Add silver nitrate solution * A precipitate of a silver halide will form

Question 46

Precipitate colour based on Halide | Precipitate- solid that doesn't dissolve in a liquid

Answer 46

Flourine = none formed Chloride = white Bromide = cream Iodide = yellow

Question 47

To confirm test for Halides

Answer 47

* Add ammonia (NH3) ↳ it is sometimes difficult to see precipitate based on te halide test ↳ ammonia allows verification **Dilute Ammonia** * Only breaks down the precipitate in AgCl into a solution * Unaffects AgBr & AgI **Concentrated Ammonia** * Only breaks down precipitate in AgBr into a solution * Unaffacts AgI AgI is unaffected by both types of ammonia

Question 48

Polyatomic Ions | Carbonates (CO2)

Answer 48

* If heated or HCl is added it breaks the solution down * CO2 is given off ↳ collect it & put into limewater Positive Test: turns cloudy

Question 49

Polyatomic Ions | Sulfate (SO4 2-)

Answer 49

* Use HCl ↳ removes contaminates * Followed by BaCl ↳ produces BaSO4 (contains sulfur) Positive Test: white precipitate present

Question 50

Ammonium Compounds | (NH4 +)

Answer 50

* NH3 can be detected using damp red litmus paper ↳ turns blue * For NH4+ add NaOH & heat gently ↳ gives off NH3 gas (litmus paper test + smells) If NH3 is involved, NH4 ions are present in sample