Inorganic Chapter 2: Group 2 & Group 7

Question 1

What is group 2 called?

Answer 1

Alkaline Earth metals

Question 2

What is trend in Atomic Radius down group 2?

Answer 2

It increases - no. of shells increases

Question 3

What is the trend in first ionisation energy down group 2?

Answer 3

It decreases - electrons get further away from the nucleus - easier to remove

Question 4

What is the trend in reactivity down group 2?

Answer 4

It increases - electrons are easier to remove due to distance from nucleus

Question 5

What is the trend in melting points down group 2?

Answer 5

Generally decreases - Metal ions get bigger, nuclei get further away from the delocalised electrons, easier to break bonds

Question 6

What ions do group 2 elements form?

Answer 6

2+ ions

Question 7

What do group 2 elements produce when reacting with water?

Answer 7

A metal hydroxide & Hydrogen

E.g. Ca + 2H₂O -> Ca(OH) + H₂

Question 8

What happens to the oxidation state of group 2 elements when they react?

Answer 8

They are oxidised from a state of 0 to +2

Question 9

What are the two factors that decrease first ionisation energy down group 2?

Answer 9

Increased shielding
Increased atomic radius

Question 10

What do solubility trends with group 2 elements depend on?

Answer 10

The compound anion (OH, SO₄, etc)

Question 11

What is the trend down group 2 of solubility with singly charged anions?

Answer 11

Increases

Question 12

What is the trend down group 2 of solubility with doubly charged anions?

Answer 12

Decreases

Question 13

How can you test for sulfate ions?

Answer 13

Add acidified barium chloride, see a white ppt on a positive result

Question 14

What are group 2 elements used for?

Answer 14

Neutralising acidity - often in agriculture or antacids
Magnesium is used to extract Titanium
Calcium compounds used to remove SO₂
‘Barium meals’ for X-rays

Question 15

How is Magnesium used to extract titanium?

Answer 15

It reduces the Ti

TiCl₄ + 2Mg -> Ti + 2MgCl

Question 16

How are calcium compounds used to remove SO2?

Answer 16

Flue gas desulfurisation - Mix the compound (CaO or CaCO₃) with water, then sprayed it onto the flue gases.

CaO + 2H2O + SO2 -> CaSO3 + 2H2O
CaCO3 + 2H2O + SO2 -> CaSO3 + 2H2O + CO2

Question 17

What is a ‘Barium meal’ and how does it work?

Answer 17

People eat small amount of barium sulfate, which is opaque to X-rays, and will coat the tissue of the digestive tract, showing it on X-rays to diagnose issues.

Question 18

What is Group 7 called?

Answer 18

The Halogens

Question 19

What ions do group 7 form?

Answer 19

1- ions

Question 20

What is the trend of boiling points down group 7?

Answer 20

They increase - increasing strength of VdW forces as size increases

Question 21

What is the trend in electronegativity down group 7?

Answer 21

It decreases - larger atoms have less attracting power than smaller atoms

Question 22

What happens when you add a halogen to a halide solution formed with a less reactive halogen?

Answer 22

The less reactive halogen will be displaced & a new halide will be formed

Question 23

What is the general rule for halide displacement?

Answer 23

The halogen will displace a halide if it’s made from a halogen below it in the periodic table.

Question 24

How can we use displacement reactions of halides?

Answer 24

To determine which halide is present in a solution

Question 25

What are some uses of Halogens?

Answer 25

Bleach Cleaning swimming pools

Question 26

How do you make bleach?

Answer 26

Sodium Hydroxide & Chlorine 2NaOH + Cl2 -> NaClO + NaCl + H2O

Question 27

How does chlorine kill bacteria in water?

Answer 27

It undergoes disproportionation, and the chlorate (I) ions that are formed kill bacteria. Cl2 + H2O <-> 2H⁺ + Cl- + ClO-

Question 28

What are some risks associated with chlorine water treatment?

Answer 28

Chlorine gas is toxic if you breathe it in Organic compounds within water can form carcinogenic chlorinated hydrocarbons when reacting with chlorine

Question 29

What is the trend of reducing power going down group 7?

Answer 29

It increases - electrons are further away from the nucleus & there is greater shielding effect.

Question 30

What is the reaction of flouride or chloride with sulfuric acid?

Answer 30

Produces HF or HCl - reaction stops there e.g. NaF + H2SO4 -> NaHSO4 + HF

Question 31

What is the reaction of Bromide with sulfuric acid?

Answer 31

Produces HBr, which then produces sulfur dioxide, bromine, and water with the sulfuric acid NaBr + H2SO4 -> NaHSO4 + HBr HBr + H2SO4 -> Br2 + SO2 + H2O

Question 32

What is the reaction of Iodide with sulfuric acid?

Answer 32

Produces HI, which will then reduce H2SO4 and then further reduces the produced SO2 to H2S. (Equations same as Br) 6HI + SO₂ -> H₂S + 3I₂ + 2H₂O

Question 33

What solution is used to test for halides?

Answer 33

Silver Nitrate - forms a different colour precipitate depending on the ion. Next, add Ammonia to identify possibility of Chlorine.

Question 34

What colour ppt does silver nitrate form with Flourine?

Answer 34

No ppt

Question 35

What colour ppt does silver nitrate form with Chlorine?

Answer 35

White

Question 36

What colour ppt does silver nitrate form with Bromine?

Answer 36

Cream

Question 37

What colour ppt does silver nitrate form with Iodine?

Answer 37

Yellow

Question 38

What is the result of adding ammonia after a silver nitrate test?

Answer 38

Chlorine will form a white ppt Bromine will form a cream ppt Iodine will form a yellow ppt

Question 39

What tests can you use to identify group 2 ions?

Answer 39

Flame tests NaOH tests

Question 40

What colour ppt does Mg form with NaOH?

Answer 40

white ppt

Question 41

What colour ppt does Ca form with NaOH?

Answer 41

Slight white ppt

Question 42

What colour ppt does Sr form with NaOH?

Answer 42

Slight white ppt

Question 43

What colour ppt does Ba form with NaOH?

Answer 43

None

Question 44

What colour does Ca go in a flame test?

Answer 44

Brick red

Question 45

What colour does Sr go in a flame test?

Answer 45

red

Question 46

What colour does Ba go in a flame test?

Answer 46

Green

Question 47

What is a good test for ammonium ions?

Answer 47

Red litmus paper & NaOH - add NaOH to an ammonium solution, it'll form ammonia gas, which will turn the litmus paper blue due to being alkaline.

Question 48

How do you test for hydroxides?

Answer 48

Use a pH indicator, an alkaline result will form if the solution has hydroxides

Question 49

How can you test for carbonates?

Answer 49

Add dilute hydrochloric acid, the solution will begin to fizz. Bubble this gas through limewater, and if the limewater goes cloudy, the solution contained carbonate ions.