Ch3.1 The Periodic Table

Question 1

How many elements were there thought to be by the Ancient Greeks?

Answer 1

4: earth, fire, water and air

Question 2

When and why was John Dalton relevant?

Answer 2

• first to give chemical symbols to elements in the early 19th century

Question 3

When and why was Johannes Dobereiner relevant?

Answer 3

• he discovered mathematical patterns in the elements (triads)
• first to attempt arranging elements into groups
• 1829

Question 4

When and why was John Newlands relevant?

Answer 4

• law of octaves: first recognition of periods in elements
• if elements are in repeating rows of 7, their properties repeat
• 1864

Question 5

When and why was Dmitri Mendeleev relevant?

Answer 5

• arranged known elements in horizontal rows (periods) and vertical columns (groups) according to atomic weight
• left gaps for undiscovered elements and predicted properties of them with accuracy
• 1869

Question 6

What happened between Mendeleev and Baron de Chancourtois?

Answer 6

• BdC sent a manuscript to M 1 year before M’s discovery of the periodic table
• contained writing and drawing of a periodic table
• M sent to publishers without the drawing then 1 year later ‘came up’ with the periodic table

Question 7

Describe the appearance of fluorine

Answer 7

A pale yellow gas

Question 8

Describe the appearance of chlorine

Answer 8

Green gas

Question 9

Describe the appearance of bromine

Answer 9

Brown solid

Question 10

Describe the appearance of iodine

Answer 10

Grey solid

Question 11

Describe the appearance of astatine

Answer 11

Black solid

Question 12

How do the halogens achieve stability?

Answer 12

They exist diatomically

Question 13

Why do the halogens’ boiling points increase as you move down the group?

Answer 13

• atoms get bigger (more shells)
• more electrons in cloud
• stronger London forces
• more energy needed to overcome

Question 14

State properties of halogens

Answer 14

• very reactive
• non-metals
• dense, coloured, poisonous gases
• react with s-block metals to form white salts
• 7 e- in outer shell

Question 15

Describe the uses of fluorine

Answer 15

Used to make PTFE in non-stick frying pans and fluoride is used to prevent tooth decay

Question 16

Describe the uses of chlorine

Answer 16

Kills bacteria in pools and drinking water, makes bleach and plastics

Question 17

Describe the uses of bromine

Answer 17

Used in photographic film

Question 18

Describe the uses of iodine

Answer 18

Antiseptic, essential part of diet for thyroid

Question 19

What are the trends as you move down the group of halogens?

Answer 19

• less reactive
• darker in colour
• less electronegative
• less oxidising
• higher melting and boiling points

Question 20

Which of the halogens doesn’t exist as a liquid?

Answer 20

Iodine, it goes through sublimation (solid straight to gas)

Question 21

List the reactivity series and the way to remember it

Answer 21

Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold

Passive
Smoking
Can
Make
All
Zombies
In
To
Lazy
Crazy
Sex
Gods

Question 22

What would the products be in a displacement reaction between chlorine and potassium iodide?

Answer 22

Potassium chloride and iodine

Question 23

What chemical is used to distinguish between iodine and bromine

Answer 23

Cyclohexane

Question 24

How are halide ions identified?

Answer 24

Using aqueous silver ions:
add nitric acid and silver nitrate which forms acidified silver nitrate

Question 25

When aqueous silver ions are added to halide ions, what colour to they go depending on which halogen they derive from?

Answer 25

- chlorine = white - bromine = cream - iodine = yellow

Question 26

After adding aqueous silver ions, if the colours are hard to distinguish between, how can this be solved?

Answer 26

- add ammonia -dilute ammonia turns the white of Cl colourless - concentrated turns the cream of Br colourless - the yellow of I cannot be turned colourless

Question 27

What is brine?

Answer 27

Very concentrated NaCl solution (very salty water)

Question 28

How is bleach manufactured?

Answer 28

Chlorine is reacted with sodium hydroxide to produce sodium chloride, sodium chlorite (bleach) and water

Question 29

What happens to chlorine during the reaction of forming bleach?

Answer 29

It is both oxidised and reduced meaning it is a disproportionation reaction

Question 30

How is group 2 on the periodic table similar to group 1?

Answer 30

- metals from both groups make alkaline solutions and hydrogen gas when added to water - both groups get more reactive as you move down

Question 31

Where are alkaline earth metals found?

Answer 31

In large quantities in rocks

Question 32

What rock is magnesium found in?

Answer 32

Dolomite

Question 33

What rock is calcium found in?

Answer 33

Limestone

Question 34

What rock is strontium found in?

Answer 34

Strontianite