C3- Periodic table

Question 1

What were the two ways scientists in the 19th century organised elements?

Answer 1

• by their physical and chemical properties

- by their atomic weight

Question 2

What did Newland do?

Answer 2

Put elements in the order of their atomic massive

And said that every 8th element had similar properties (law of octaves)

Question 3

What were the criticisms of newland’s ideas?

Answer 3

• some groups had a mix of metals and non metals
• elements in some groups didn’t have similar properties
• he didn’t leave gaps for elements to be discovered
• his law only worked for the first few elements

Question 4

What did Mendeleev do ?

Answer 4

He arranged the elements in a periodic way (regular occurring pattern)

• left gaps for undiscovered elements to show otherwise, elements would not have similar properties to others in the group
• predicted the atomic masses and properties of undiscovered elements

Question 5

Why did some scientists disapprove of Mendeleevs work?

Answer 5

-not much evidence to suggest the elements fit together in that way

Question 6

What is the modern periodic table based on?

Answer 6

Electronic structure

• table arranged in order of atomic number
• all elements put into groups

Question 7

What happens to the electrostatic attraction when the electron gets further away from the nucleus?

Answer 7

The attraction becomes weaker

Question 8

What is shielding?

Answer 8

When the electrostatic attraction of the nucleus is less because of a lot of inner electrons that ‘shield’ the nuclear charge

Question 9

Why are group one metals more reactive as you go down the group?

Answer 9

There’s less attraction from the nucleus holding the electron in place due to increased distance and shielding

Question 10

What are the features of group 1?

Answer 10

• low density
• react with non metals to form ionic compounds
• release hydrogen when reacting with water
• form hydroxides that dissolve in water to give alkaline solutions (colourless)

Question 11

What happens when lithium is put in water?

Answer 11

It fizzes and moves around the water

Question 12

What happens when sodium is put into water?

Answer 12

Produces a flame and moves around the surface of the water

Question 13

What happens when potassium reacts with water?

Answer 13

It spits sparks , has a flame and moves around the surface of the water

Question 14

What kind of ion do the alkali metals want to form?

Answer 14

A 1+ ion

Question 15

What are the properties of transition metals compared to group 1?

Answer 15

• higher melting points and boiling points (except mercury)
• harder and stronger
• less reactive with water and oxygen

Question 16

What are transition metals good for in the industry?

Answer 16

• conductors of heat and electricity

- used in structural materials

Question 17

What can transition metals do?

Answer 17

• Form ions with different charges
• Form coloured compounds (copper sulphate)
• Useful as catalysts (iron in haber process etc)

Question 18

What coloured compound does Fe2+ form?

Answer 18

Green compounds

Question 19

What coloured compound does Fe3+ form?

Answer 19

Reddish brown

Question 20

What are the properties of group 7?

Answer 20

• poor conductors
• poisonous
• produce coloured vapours

Question 21

What happens as you move down group 7?

Answer 21

They become less reactive because it’s harder to gain an extra electron
Higher melting and boiling point

Question 22

What compound is formed when halogens react with metals?

Answer 22

Ionic compound

Question 23

What is the ion produced by group 7?

Answer 23

A halide ion (-1 charge)

Question 24

What is the colour and properties of fluorine?

Answer 24

• very reactive

- poisonous yellow gas

Question 25

What are the properties and colour of chlorine?

Answer 25

• fairly reactive

- poisonous dense green gas

Question 26

What is the property and colour of bromine ?

Answer 26

• dense

- poisonous, red-brown volatile liquid

Question 27

What is the property and colour of iodine?

Answer 27

-dark grey crystalline solid or purple vapour

Question 28

What does hard water make?

Answer 28

Scum and scale

Question 29

How is scum made?

Answer 29

Dissolved calcium ions and magnesium ions in the water reacting with soap is insoluble

Question 30

How is scale formed?

Answer 30

When heated, hard water forms scale

Question 31

What problems can scale cause?

Answer 31

• reduce the efficiency of heating systems which may need to be replaced
• blocks pipes
• thermal insulator

Question 32

What is hardness caused by?

Answer 32

Ca2+ and Mg2+ ions

Question 33

What are the benefits of the ions in hard water?

Answer 33

• good for bone and teeth development

- less risk of heart disease

Question 34

What is temporary hard water?

Answer 34

Can be softened by heating or boiling

-caused by hydrogenate ion

Question 35

What is permanent hard water?

Answer 35

Remains hard even when heated or boiled

Caused by dissolved calcium sulfate

Question 36

How can washing soda (sodium carbonate) soften water?

Answer 36

The added carbonate ions react with the Ca and Mg ions to make an insoluble precipitate of calcium carbonate and magnesium carbonate

Question 37

How can hardness be removed through an ion exchange column ?

Answer 37

The Columns contain resins that have lots of sodium ions and exchange them for calcium or magnesium ions in the water