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Flashcards in Group 2 And Group 7 Deck (31)
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1
Q

What happens to Group 2 elements when they react?

A

They lose 2 electrons.

2
Q

In group 2 what happened to the atomic radius down group 2?

A

Atomic radius increases down the group. This is because extra electron shells are added as you go down the group so the atomic radius gets larger.

3
Q

In group to what happens the first ionisation energy down the group?

A

First ionisation energy decreases down the group.

Each element down group 2 has an extra electron shell compare to the one above these inner child shield the outer electrons from the attraction of the nucleus the extra shall also means the outer electrons are further away and so reduce its nucleus’s attraction. Both of these factors make it easier to remove the electrics resulting in a lower first ionisation energy.

4
Q

What happens to reactivity down group 2?

A

Reactivity increases down the group.

As you go down the group, the first ionisation energy decreases. When group 2 elements they react they lose electrons, forming positive ions. The easier it is to lose electrons the more reactive the element, so reactivity increases down the group.

5
Q

What happens to melting points down group 2?

A

The melting points generally decrease down the group.

Group 2 elements have a metallic structure with positive ions in a crystal structure surrounded by delocalised electrons. Going down the group the metal ions get bigger, but the number of delocalised electrons don’t change. There is a larger ionic radius, the further away the delocalised electrons are from the positive nuclei the message actually feel. So it takes less energy to break the bonds, which means melting points generally decrease as you go down the group. However there is a drop at magnesium because the of the crystal structure changes.

6
Q

Group 2 elements react with water. What do they react to give?

A

One group 2 elements react, they are oxidised from a state of 0 to +2 forming 2+ ions. The group to metals react with water to give a metal hydroxide and hydrogen.

They react more readily down the group because the ionisation energy decreases.

In this reaction water is acting as the oxidising agent.

7
Q

Solubility trends in group 2 depend on what?

A

Solubility trends tend to depend on the compound anion.

Compounds of group 2 elements that complain contain singly charged negative ions increase in solubility down the group.

Compounds of group 2 elements that contain doubly charged negative ions decrease in solubility down the group.

8
Q

When reacting a group 2 elements with a hydroxide, how is solubility in group to?

A

The solubility decreases down the group.

Magnesium is the least soluble whereas barium is the most soluble.

9
Q

When reacting a group 2 elements with a sulphate what happened to the reactivity in group 2?

A

Solubility increases up the group.

Magnesium is the most soluble whereas Barium is the least soluble.

10
Q

Group 2 compounds are used to neutralise city, give some examples and how they work.

A

1) Calcium hydroxide is used in agriculture to neutralise acidic soils.
2) Magnesium hydroxide is used in some indigestion tablets as an antacid - this is a substance which neutralises excess stomach acid.

Ionic question for the neutralisation is
H^+ + OH- —> H2O

11
Q

What is Barium Sulfate used in?

A

Barium sulphate is used in barium meals.

Barium Sulfate is opaque to x-rays, they won’t pass through it. It’s used in meals where the patient digests that the barium sulphate covers the tissues, making them show up on x-rays, showing the structure of the organs. It’s used to diagnose problems with the oesophagus, stomach or intestines.

12
Q

Which group to element is used in the extraction of titanium?

A

Magnesium.

Magnesium is used as part of the process of extracting titanium from its ore.

The main titanium ore, titanium (IV) oxide is first converted to titanium (IV) chloride by heating with carbon in a stream of chlorine gas.
The titanium chloride is then purified by fractional distillation, before being reduced by magnesium in a furnace at almost 1000° C.

In this equation Mg is reducing agent:
TiCl4 + 2Mg —> Ti + 2MgCl2

13
Q

What group 2 element is used to remove sulfur dioxide from fossil fuels?

A

Calcium oxide and calcium carbonate.

The acidic sofa dioxide can be removed from fluegases by reacting with an alkali-this process is called wet scrubbing.

Powdered calcium oxide/calcium carbonate can you be used both for this. A slurry is made by mixing calcium oxide/calcium carbonate with water. It’s then sprayed onto the flue gases. Sulfur dioxide reacts with the calcium oxide/carbonate and produces a solid waste product, calcium sulfite.

CaO + 2H2O + SO2 —> CaSO3 + 2H2O
CaCO3 + 2H2O + SO2 —> CaSO3 + 2H2O + CO

14
Q

Halogens a highly reactive nonmetals of group 7.

Have a great state the boiling point trends in this group.

A

The boiling points increase down the group.
This is due to the increasing strength of the Van derWaals forces as the size and relative mass of the molecules increases. This trend is shown in the changes of physical state from fluorine (gas) iodine (solid).

15
Q

Halogens a highly reactive nonmetals of group 7.

Have a great state the electronegativity trends in this group.

A

Electronegativity decreases down the group.
Electronegativity, is the tendency of an atom to attract the bonding pair of electrons. The halogens are all highly electronegative elements. But larger atoms attract less than smaller ones. This is because the electrons are further from the nucleus and I shielded by more electrons.

16
Q

Chlorine and sodium hydroxide make:

A

Bleach.

2NaOH + Cl2 —> NaClO + NaCl + H2O

17
Q

What happened to the reducing power of halides down the group?

A

The reducing power of halides increases down the group.

To reduce something, the halide ion needs to lose an electron from its outer shell. How easy this is depends on the attraction between the nucleus and the outer electrons. As you go down, the attraction gets weaker because:
The ions get bigger, so the electrons are further away from the positive nucleus
There are extra in electron shells, so that the greater shielding fact.
So, the further down the group the halide ion is, the easier it loses electrons and the greater it’s reducing power.

18
Q

Describe the reaction between Cl/F and sulphuric acid.

A

HF and HCl is formed, as gas comes into contact with air misty fumes are seen. But these aren’t strong enough reducing agent to reduce the sulfuric acid, so the reaction stops here. It’s not a redox reaction.

19
Q

Describe the reaction between Br and sulphuric acid.

A

Misty fumes of HBr are released.
The HBr is a stronger reducing agent and reacts with the H2SO4 in a redox reaction.
The reaction produces choking fumes of SO2 and orange fumes of Br2.

20
Q

Describe the reaction between I and sulphuric acid.

A

First reaction get misty fumes of HI gas.
HI reduces H2SO4 and reacts in a redox reaction.
HI is a strong reducing agent and reduces SO2 to H2S
Solid iodine is also formed in this reaction.

21
Q

State the results of reacting silver nitrate solution with halides.

A

Fluoride: no precipitate
Chloride: white precipitate
Bromide: cream precipitate
Iodide: yellow precipitate

Iodide forms fastest, chloride forms slowest.

22
Q

State the results of adding ammonia solution to the silver nitrate halide solution.

A

Chloride: white precipitate, dissolves in dilute NH3
Bromide: cream precipitate, dissolves in conc NH3
Iodide: yellow precipitate, insoluble in conc NH3

Chloride is most soluble, iodide is least soluble.

23
Q

Describe how the test for halides occurs:

A

Add dilute nitric acid to remove ions which might interfere with the test.
Add a few drops of silver nitrate solution.
A precipitate is formed.

If adding ammonia solution, just add a few drops of ammonia solution.

24
Q

Describe the flame test used to identify group 2 ions:

A

1) Dip a nichrome sure loop in conc HCl
2) Then dip the wire loop into the unknown compound.
3) Hold the loop in the clear blue part of a Bunsen burner flame.
4) Observe the change.

25
Q

State the colours produced in the flame test used to identify group to ions.

A

Calcium: brick red
Strontium: red
Barium: pale green

26
Q

How can you use red litmus paper and NaOH to test for ammonium ions?

A

Ammonia gas is alkaline - so you can test for it using a damp piece of red litmus paper. (The litmus paper needs to be down for the ammonia gas can dissolve). If there is ammonia present, the paper will turn blue.
If you add hydroxide ions to a solution containing ammonium ions, they react to produce ammonia gas and water.
NH4+ + OH- —> NH3 + H2O

27
Q

Give the test for sulphates:

A

To identify a sulfate ion (SO4^2-), you add a dilute HCl, followed by BaCl2 solution.
Ba2+ + SO4^2- —> BaSO4
If a white precipitate of barium sulphate forms, it means the original compound contains a sulphate.

28
Q

Describe how you would use a pH indicator test for hydroxides:

A

Hydroxide ions make solutions alkaline.

1) Dip a piece of red litmus paper into the solution.
2) If hydroxide ions are present, the paper will turn blue.

29
Q

Describe the results of the test for halides with silver nitrate solution:

A

Chloride: white precipitate of silver chloride
Bromide: cream precipitate of silver bromide
Iodide: yellow precipitate of silver iodide

30
Q

Describe the test for Halides with Silver Nitrate solution:

A

Do you test for chloride, bromide or iodide ions you:

Add dilute nitric acid (HNO3), followed by silver nitrate (AgNO3).

31
Q

Hydrochloric acid can help detect carbonates, state how this is.

A

When you add die loot hydrochloric acid, solution containing carbon ions will fizz. This is because the carbonate ions react with the hydrogen ions in the acid to give carbon dioxide:
Co3^2- + 2H+ —> CO2 + H20
You can test for carbon dioxide is using lime water.
Carbon dioxide turns lime water cloudy - put gas in like water and see what happens.