Periodic table

Question 1

Who first discovered atoms ?

Answer 1

Democritus in 400 BCE

Question 2

What did John Dalton do ?

Answer 2

Arranged elements in order of their atomic weights

Question 3

What did John Newlands do ?

Answer 3

Arranged elements in order of mass, and noticed that every eight element seemed similar. He demonstrated this ‘Law of Octaves’ using a table

Question 4

What did Mendeleev do ?

Answer 4

Left gaps for missing elements and predicted their properties
Swapped the order of some elements

Question 5

Why was Newlands table not accepted by peers ?

Answer 5

Two elements in the same box
Only worked for first 20 elements
No reason for why every 8 seemed similar

Question 6

How did Mendeleev justify swapping elements ?

Answer 6

Claimed they were not weighed properly

Question 7

Why did Mendeleev leave gaps in his table ?

Answer 7

To make the patterns of chemical properties fit

Question 8

How did Mendeleev explain the gaps he left ?

Answer 8

Undiscovered elements

Question 9

Why did the discovery of gallium prove that Mendeleev was correct ?

Answer 9

Its properties matched those predicted

Question 10

Differences between Mendeleev’s table and the modern periodic table

Answer 10

Modern table ordered by atomic number, Mendeleev ordered atomic mass
Modern table has more elements
There are no gaps in the periodic table

Question 11

What is a group ?

Answer 11

The columns - all members share the same number of electrons on the outer shell

Question 12

What is a period ?

Answer 12

The rows - all members have the same number of electron shells

Question 13

Name for group 1 elements

Answer 13

Alkali metals

Question 14

Name for group 2 elements

Answer 14

Alkaline earth metals

Question 15

Name for group 7 elements

Answer 15

Halogens

Question 16

How does hardness of group 1 metals change as you go down the group ?

Answer 16

Become softer and easier to cut

Question 17

Density of group 1 metals

Answer 17

Low densities - Li, Na, K all float on water

Question 18

Melting points of group 1

Answer 18

Low

Question 19

Why do melting points of group 1 decrease as you go down the group ?

Answer 19

Metallic bonding gets weaker

Question 20

How reactive are group 1 ?

Answer 20

Very reactive and have to be stored in oil to prevent reaction with oxygen

Question 21

What happens when a fresh piece of g1 metal is cut ?

Answer 21

Shiny when freshly cut but tarnishes quickly due to oxide forming

Question 22

Observations when g1 dropped in water

Answer 22

Fizzing
Floating
Move around on surface
‘dissolves’
Na + K melt
K has flame
Rb + Cs explode

Question 23

What is the solution left after a g1 is dropped in water

Answer 23

Alkaline

Question 24

Why does reactivity of g1 increase as you go down the group ?

Answer 24

The outer electrons are further from the positive nucleus. Weaker attraction means that electron is easier to move.

Question 25

Colour of pure flourine

Answer 25

yellow

Question 26

colour of pure chlorine

Answer 26

green

Question 27

colour of pure bromine

Answer 27

orange

Question 28

colour of pure iodine

Answer 28

grey

Question 29

colour of pure astatine

Answer 29

black

Question 30

Why does the melting points of halogens increase as you go down the group

Answer 30

Intermolecular forces become stronger as you go down the group

Question 31

Why are halogens less reactive as you go down the group ?

Answer 31

Halogens gain an electron to gain a full outer shell. The nearer the outer shell is to the nucleus, the stronger the attraction for the incoming electron and therefore the more reactive the halogen is.

Question 32

What happens in a reaction between halogens ?

Answer 32

A more reactive halogen displaces a less reactive halogen

Question 33

Reduction is when

Answer 33

an atom gains electrons

Question 34

oxidation is when

Answer 34

an atom loses electrons

Question 35

Physical properties of halogens

Answer 35

Poor conductor Brittle solids Low melting points Density increases down the group

Question 36

Test for chlorine

Answer 36

Damp blue litmus paper turns red then gets bleached white

Question 37

Why are noble gases uncreative ?

Answer 37

They have a full outer shell so they do not lose or gain electrons

Question 38

How do boiling points and densities of noble gases change in the group ?

Answer 38

Increase with atomic number

Question 39

How do forced of attractions change in noble gases as you go down the group

Answer 39

Mpt and Bot increase due to stronger intermolecular forces

Question 40

Uses of helium

Answer 40

Diving Airships - low density + unreactive

Question 41

Uses of neon

Answer 41

Neon lights - gas glows when electrical current is passed through

Question 42

Uses of argon

Answer 42

Used in old light bulbs to stop tungsten filament burning

Question 43

Uses of krypton and xenon

Answer 43

Used in lasers

Question 44

Uses of radon

Answer 44

Radioactive gas - causes cancer

Question 45

Physical properties of transition metals

Answer 45

Hard + strong Malleable Dense High mpt + bpt Ductile Good conductors Shiny

Question 46

Which group are good catalysts ?

Answer 46

Transition metals