Topic 6 - Groups In Periodic Table

Question 1

How are elements arranged in the periodic table?

Answer 1

Ordered by increasing atomic number
Elements in same group(column) = same no of outer shell electrons
Elements in same period(row) = same no of electron shells

Question 2

How many electrons are in the outer shell of a group 1 element?

Answer 2

1

Question 3

Why do elements in the same group have similar chemical properties?

Answer 3

Have same no of electrons in outer shell

Question 4

What group of the periodic table are the alkali metals?

Answer 4

Group 1

Question 5

List 2 properties of alkali metals

Answer 5

Relatively low melting pts

Soft

Question 6

Why are group 1 elements called the alkali metals?

Answer 6

They react with water to form alkaline solutions (pH bigger than 7)

Question 7

What are the products of the reaction between lithium and water?

Answer 7

Lithium hydroxide and hydrogen

Question 8

Write a balanced symbol equation for the reaction of sodium with water

Answer 8

2Na + 2H₂O -> 2NaOH + H₂

Question 9

Why should alkali metals be stored in oil?

Answer 9

To prevent them reacting with water vapour and oxygen in the air

Question 10

What would be observed when lithium reacts with water?

Answer 10

Slowest reaction of alkali metals
Bubbles of hydrogen produced
Doesn’t melt (highest melting pt of alkali metals)

Question 11

What would be observed when sodium reacts with water?

Answer 11

Faster reaction than lithium
Floats on surface (less dense than water)
Bubbles of hydrogen produced - cause sodium to whizz around surface
Melts as enough energy is given out to meet melting pt

Question 12

What would be observed when potassium reacts with water?

Answer 12

More violent reaction than sodium
Bubbles of hydrogen produced - cause potassium to whizz round surface
Melts into shiny ball
Burns with lilac flame

Question 13

What is the order of reactivity of the first 3 alkali metals with water?

Answer 13

Lithium (least)
Sodium
Potassium (most)

Question 14

Using the reactions of the first 3 alkali metals with water, predict the reactivity trend down group 1

Answer 14

Reactivity increases down group 1

Question 15

Why does reactivity increase down group 1?

Answer 15

No of electron shells increases down the group so there is more electron sheilding.
Is weaker attraction between + nucleus and outer electron shell.
Means is easier to remove outer shell electron to form + metal ion

Question 16

Which group 1 element would you expect to react most violently with water?

Answer 16

Reactivity increases down the group so francium will react most violently with water

Question 17

What group are the halogens in? Why?

Answer 17

Group 7 - they have 7 outer shell electrons

Question 18

What is the colour and state of chlorine at room temp?

Answer 18

Pale green gas

Question 19

What is the colour and state of bromine at room temp?

Answer 19

Red-brown liquid

Question 20

What is the colour and state of iodine at room temp?

Answer 20

Black solid

Question 21

Why are the halogens at different states at room temp? What is the trend down the group?

Answer 21

They have different melting and boiling pts.

As you go down the group, they increase

Question 22

What state would you expect the halogens flourine and astatine to be at room temp?

Answer 22

Flourine is above chlorine so should have a boiling pt lower than it. Means it would be a gas at room temp.
Astatine is below iodine in group 7 so should have a higher melting pt. Can predict that is would be a solid at room temp.

Question 23

Why does melting and boiling pt increase down group 7?

Answer 23

Molecules get bigger down the group - more intermolecular forces to overcome during melting/boiling - more energy required

Question 24

What is the chemical test for chlorine?

Answer 24

Damp litmus paper placed into test tube of gas

If chlorine present, litmus paper will turn red then white die to bleaching effect of chlorine

Question 25

Halogens are diatomic. What does this mean?

Answer 25

They form molecules consisting of 2 atoms | Cl₂ Br₂

Question 26

What charge does a halide ion carry? Why?

Answer 26

-1 | They gain one electron to have a stable electron configuration

Question 27

What is produced when a halogen reacts with a metal?

Answer 27

Metal halide salt

Question 28

Write a balanced symbol equation for the reaction between bromine and sodium

Answer 28

Br₂ + 2Na -> 2NaBr

Question 29

Write a balanced symbol equation for the reaction between chlorine and calcium

Answer 29

Cl₂ + Ca -> CaCl₂

Question 30

Predict the product of the reaction between magnesium and fluorine

Answer 30

Magnesium fluoride (MgF₂)

Question 31

Write a work equation for the reaction between iodine and potassium

Answer 31

Iodine + potassium -> potassium iodide

Question 32

Describe the trend in reactivity of the halogens. How does this affect the rate of reaction?

Answer 32

Reactivity decreases down group 7 | Rate of reaction decreases down group 7

Question 33

What is formed when hydrogen reacts with a halogen?

Answer 33

Hydorgen halides | HCl, HBr

Question 34

Chlorine reacts with hydrogen in the presence of sunlight but bromine requires a flame. Why?

Answer 34

Reactivity decreases down the group so bromine requires more energy for the reaction to occur

Question 35

What is formed when a hydrogen halide dissolves in water?

Answer 35

An acidic solution. Hydrogen ions dissociate, making the solution acidic

Question 36

Write a balanced symbol equation for the reaction between hydrogen and chlorine

Answer 36

H ₂ + Cl ₂ -> 2HCl

Question 37

Predict the product of the reaction between hydrogen and fluorine

Answer 37

Hydrogen fluoride

Question 38

When does a halogen displacement reaction occur?

Answer 38

When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide

Question 39

Why will halogen A only be displaced by halogen B if B is above A in group 7?

Answer 39

The more reactive halogen (B) will displace the less reactive one to become part of the ionic compound. Reactivity increases as you go up the group so B must be higher to be more reactive than A

Question 40

Which halogens can chlorine displace from an aqueous ionic solution?

Answer 40

Chlorine can displace any halogens below it in group 7. It will displace iodine and bromine.

Question 41

Which halogens cant be displaced from an aqueous ionic solution by bromine?

Answer 41

Bromine cant displace any halogens above it in group 7. These are chlorine and fluorine.

Question 42

Why cant iodine displace chlorine or bromine from an aqueous ionic solution?

Answer 42

Because reactivity decreases down the group and iodine is below chlorine and bromine in group 7.

Question 43

Write the word equation for the reaction between chlorine and potassium bromide

Answer 43

Chlorine + potassium bromide -> potassium chloride + bromine

Question 44

Write the word equation for the reaction between bromine and calcium chloride

Answer 44

No reaction will occur because bromine is less reactive than chlorine so chlorine wont be displaced

Question 45

Write the balanced symbol equation for the reaction that takes place netween bromine and potassium iodide

Answer 45

Br ₂ + 2Kl -> I ₂ + 2KBr

Question 46

Which halogens would you expect astatine to be able to displace?

Answer 46

None. Its at bottom of group 7 so has lowest reactivity

Question 47

Why does reactivity decrease down group 7?

Answer 47

Outer shell is further from nucleus as go down group Electron sheilding increases Attraction between nucleus and outer electrons decreases so is harder for atom to gain an electron - reactivity decreases

Question 48

What colours are solutions of chlorine, bromine and iodine?

Answer 48

Chlorine water - colourless Bromine water - orange Iodine solution - brown

Question 49

What would you observe when chlorine is added to potassium bromide?

Answer 49

Cl ₂ + 2KBr -> Br ₂ + 2KCl | Colour change from colourless to orange

Question 50

What is a redox reaction?

Answer 50

Reaction where oxidation and reduction take place at same time

Question 51

Are halogen displacement reactions redox reactions? Explain your answer.

Answer 51

Yes - halide ion is oxidised (loses an electron) to form a halogen atom - halogen is reduced (gains an electron) to form a halide ion

Question 52

Write 2 half equations for the reaction between chlorine and potassium bromide, state which is reduction/oxidation

Answer 52

Reduction: Cl₂ + 2e⁻ -> 2Cl⁻ Oxidation: 2Br⁻ -> Br₂ + 2e⁻

Question 53

Bromine reacts with potassium iodide. | What is reduced and what is oxidised?

Answer 53

Bromine is reduced to bromide ions | Iodide ions are oxidised to iodine

Question 54

What name is used to describe the elements in group 0 of the periodic table?

Answer 54

Noble gases

Question 55

How many electrons do the noble gases have in their outer shell?

Answer 55

8 | Have no incomplete shells of electrons

Question 56

What does chemically inert mean?

Answer 56

Not chemically active

Question 57

Why are the noble gases chemically inert?

Answer 57

Have full outer electron shells. This is a very stable electron configuration + means elements are very unreactive

Question 58

What properties of helium makes it suitable for use in balloons?

Answer 58

Is less dense than air and doesnt burn

Question 59

Why is argon used to fill electric light bulbs?

Answer 59

Very chemically inert so wont react when bulb gets hot. Is non flammable

Question 60

Why is argon used for welding?

Answer 60

Provides an inert welding atmosphere | Argon is more dense than air so keeps air away from metal

Question 61

What is the trend down group 0 in boilings pts?

Answer 61

Boiling pt increases down group 0 because the relative atomic mass increases so there are more intermolecular forces between atoms

Question 62

What is the trend in density down group 0?

Answer 62

Increases down group Helium least dense Radon most dense