Groups in period table

Question 1

Why do some elements can be classed as alkali metals etc based on their position on the period table?

Answer 1

They have the same number of electrons of electrons in their outer shell therefore they have the same chemical properties.

Question 2

What are physical properties of alkali metals?

Answer 2

• low melting points
• soft & easy to cut

Question 3

What are chemical properties of alkali metals?

Answer 3

They’re very reactive & are easily oxides & burn brightly in air

Question 4

Describe the reactions of lithium, sodium and potassium with water.

Answer 4

lithium + water -> bubbles fiercely on surface
sodium + water -> melts into ball & fizzes on surface
potassium + water -> burst into lilac flames + flies about on surface

Question 5

Explain the pattern in reactivity in terms of electronic configuration.

Answer 5

reactivity goes down the group because:
- atoms get larger so it’s easier to lose electrons as there’s an increase in electron shells
- force of attraction between nucleus & outer electrons decrease as they become further apart
- electrons become more easily lost -> more reactive

Question 6

Why are they stored in oil?

Answer 6

They’re highly reactive emo oxygen so they’re stored in oil to minimise contact

Question 7

What are the colours & physical states of chlorine, bromine and iodine at room temperature?

Answer 7

chlorine - green gas
bromine - red-brown liquid
iodine - purple

Question 8

Describe the pattern in physical properties of the halogens, chlorine, bromine and iodine -> how to predict physical properties of others?

Answer 8

• state goes from gas -> liquid. down group
• because melting & boiling point increases as u go down the group,many halogen above chlorine will be a gas £ below idioine will be a solid

Question 9

Describe the chemical test for chlorine

Answer 9

damp litmus paper is bleached then turns white

Question 10

What happens when halogens react with hydrogen?

Answer 10

they form hydrogen halides which dissolve in water to form an acidic reaction

Question 11

Explain the reactivity of halogens.

Answer 11

reactive DECREASES when you go down the group because
they gain an electron on their outer shell because :
- outer shell gets further away from nucleus
attraction between nucleus and outer electrons decrease
- electrons are gained less easily -> less reactive

Question 12

What are the reactions of fluorine, chlorine, bromine and iodine when they react with wool?

Answer 12

fluorine -> bursts into flames
chlorine -> glows brightly
bromine -> g,wow full red
iodine -> changes colour

Question 13

What are properties of nobel gases?

Answer 13

• colourless
• low me
  ting & boiling point
• poor conductors heat & electricity
  — inert [don’t react easily]

Question 14

Why are noble gases are chemically inert?

Answer 14

have full outer shells which makes them stable
act as single atoms as they don’t form bonds

Question 15

Explain how the uses of noble gases depend on their inertness, low
density​ ​and/or​ ​non-flammability.

Answer 15

Low​ ​density​ ​=​ ​Helium​ ​used​ ​in​ ​balloons​ ​and​ ​airships​ ​since​ ​it​ ​is​ ​much​ ​less​ ​dense than​ ​air,​ ​so​ ​balloons​ ​filled​ ​with​ ​it​ ​float​ ​upwards
● Inertness​ ​&​ ​non-flammability​ ​=​ ​argon,​ ​krypton​ ​and​ ​xenon​ ​inside​ ​light​ ​bulbs, stops​ ​the​ ​filament​ ​burning​ ​away
● Inertness=​ ​argon​ ​used​ ​as​ ​a​ ​shield​ ​gas​ ​during​ ​welding,​ ​it​ ​is​ ​also​ ​denser​ ​than​ ​air which​ ​keeps​ ​it​ ​away​ ​from​ ​the​ ​metal

Question 16

Describe the pattern in the physical properties of some noble gases and
use​ ​this​ ​pattern​ ​to​ ​predict​ ​the​ ​physical​ ​properties​ ​of​ ​other​ ​noble​ ​gases

Answer 16

● The​ ​boiling​ ​points​ ​of​ ​the​ ​noble​ ​gases​ ​increase​ ​with​ ​increasing​ ​relative​ ​atomic mass​ ​(going​ ​down​ ​the​ ​group).
● The​ ​densities​ ​of​ ​the​ ​noble​ ​gases​ ​increase​ ​as​ ​you​ ​go​ ​down​ ​the​ ​group