Chemistry - Tripple

Question 0

How did John Dalton arrange the table?

Answer 0

Arranged elements in order of their atomic mass

Question 1

Who created the first periodic table in 1808?

Answer 1

John Dalton

Question 2

Who created the periodic table in 1864?

Answer 2

John Newlands

Question 3

How did John Newlands arrange his periodic table?

Answer 3

Built on John Daltons idea and came up with the idea of the “law of octaves” every eighth element had similar properties so he arranged them into rows of 7

Question 4

Why was John Newlands table criticised?

Answer 4

Left no gaps- elements were still being discovered
Only worked up till calcium
His groups didn’t contain similar properties
He mixed metals and non-metals

Question 5

Who came up with the periodic table in 1869?

Answer 5

Dmitri Mendeleev

Question 6

How did Dimitri arrange the table?

Answer 6

Put elements in order of their atomic mass but left gaps this predicted new elements
Put the elements in vertical columns (groups) these were the similar properties

Question 7

How is the modern periodic table arranged?

Answer 7

Arranged in order of their atomic proton number, the group number tells us the number of electrons in the outermost shell and therefore how it reacts

Question 8

How does shielding work?

Answer 8

The further away from the nucleus the lest attracted the electron is to the nucleus
The more electrons in the inner shells the more shielded it is so the attraction is even less

Question 9

Why do group 1 metals get more reactive as they go down the group?

Answer 9

As you go down the group the larger the atom is therefore the less attracted the electron is in the outermost shell due to distance and shielding this means the electron is more easily lost

Question 10

Why do group 7 elements get less reactive going down the group?

Answer 10

The atoms get larger as you go down the group therefore there is increased distance and shielding this means that the outer shell is less likely to gain and electron

Question 11

Name the properties of the group 1 alkali metals

Answer 11

Go down more reactive and have a lower melting and boiling point
Low density
Have 1 electron in outer shell making it very reactive
Form ionic compounds with non-metals as they are keen to lose an electron
Squeaky pop
Produces hydrogen and hydroxide

Question 12

Name the properties of the group 7 halogens

Answer 12

As they go down they are 
Less reactive
Higher melting points
Higher boiling points 
- more reactive halogens will displace less reactive halogens

Question 13

What is the properties of fluorine?

Answer 13

Very reactive and has a yellow gas

Question 14

What is the properties of chlorine?

Answer 14

Fairly reactive and a dense green gas

Question 15

What are the properties of bromine?

Answer 15

Dense and poisonous and red/brown volatile liquid

Question 16

What are the properties of iodine?

Answer 16

Dark grey crystalline solid with purple vapour

Question 17

What do halogens form with metals?

Answer 17

They form ionic bonds 1- ions called halides they gain an electron

Question 18

Why can’t fluorine react in a aqueous solution?

Answer 18

Because it reacts strongly with water

Question 19

What are the properties of transition metals?

Answer 19

good conductor
Dense strong and shiny
Less reactive than group 1 metals
Much denser stronger and harder than group 1 metals
Higher melting points that group 1

Question 20

Why do transition elements have different colours?

Answer 20

Different ions form different colour compounds

Question 21

What colour is potassium chromate?

Answer 21

Yellow

Question 22

What colour is potassium manganate?

Answer 22

Purple

Question 23

What colour is copper sulfate?

Answer 23

Blue

Question 24

What colour is Fe 2+?

Answer 24

Green

Question 25

What colour is Fe3+?

Answer 25

Red/brown

Question 26

How do you test for soft water and how do you test for hard water?

Answer 26

Soft > produces lather with soap

Hard> nasty scum

Question 27

Why does hard water produce a nasty scum?

Answer 27

Dissolved calcium and magnesium ion react with soap to make scum which is insoluble to get a descent lather you should use more soap

Question 28

What does heating do to hard water?

Answer 28

Produces scale
This reduces the efficiency of the heating system which will need to be replaced
Also acts as a thermal insulator which means it takes longer to heat up e.g. A kettle

Question 29

How is hard water formed?

Answer 29

Hard water contains mg2+ ions and ca2+ ions
When rain falls on types of rocks like limestone the ions react with it and dissolve to magnesium sulfate and calcium sulfate these are both soluble. This then goes into rivers and then reservoirs and into the water supply

Question 30

What is temporary hard water caused by

Answer 30

The hydrocarbonate ion HCO3- in Ca(HCO3)2

Question 31

What is permanent hard water caused by?

Answer 31

Dissolved calcium sulfate

Question 32

How do you remove temporary hardness?

Answer 32

Boiling
The calcium hydrocarbonate decomposes to form calcium carbonate which is insoluble this is solid limescale
And the two permanent ways

Question 33

How do you make permanent hard water soft?

Answer 33

Washing soda - adding washing soda (sodium carbonate) to it, the carbonate ions react with calcium and magnesium ions to make an insoluble precipitate of calcium carbonate and magnesium carbonate. The ions are no longer dissolved in the water so cannot make it hard
- ion exchange column - removes hardness by replacing the calcium and magnesium ions with sodium and hydrogen ions

Question 34

Why do water softeners have to be topped up with salt?

Answer 34

Resin is washed with sodium chloride solution this puts the sodium ions back in

Question 35

Why is hard water good for you?

Answer 35

Calcium ions are good for teeth and bones

Less risk of developing heart disease due to minerals in hard water

Question 36

Why must water be treated?

Answer 36

It must be free of harmful poisonous salts like nitrates and phosphates
No harmful microbes as these could cause disease like cholera

Question 37

How is water in a reservoir treated?

Answer 37

1. Water passed through a mesh to get rid of twigs and leaves
2. Chemicals like aluminium sulfate and lime added this causes the dirt and impurities to clump together and microbes to stick together and sink
3. Water is passed through a gravel bed usually made of fine sand to remove and solids left
4. Water is chlorinated to kill of any microbes
5. Ph of water checked and corrected if not neutral
6. Pumped to homes

Question 38

What does filtering do?

Answer 38

Carbon > Reduces level of chlorine, pesticides and other impurities
Silver > discourages growth of bacteria
Ion exchange > removes calcium magnesium aluminium and lead

Question 39

What is distilling?

Answer 39

Boiling water to make steam and then condensing it
Pure water
To expansive
Only in labs as they dint want ions reacting

Question 40

What are the pros and cons of fluorine in water?

Answer 40

\+ reduces tooth decay
\+ been used for 50 years
\+ reduce amount of tooth decay
\+ only added in tiny amounts 
- high dosages can cause cancer and bone problems like flouris 
- ethical not right as theres no choice
- cant control intake
- benefit not significant

Question 41

What are the benefits and costs of adding chlorine to water?

Answer 41

+ prevent disease

• increase in certain cancers ad it reacts with other natural substances in the water to produce toxic by products
• ozone is alternative