Reactivity trends of group 1 and group 7 elements

Alkali metals belong to group...

• 1

• 2

• 3

• 4

Lithium will react in a similar way to...

• Calcium

• Potassium

• Fluorine

• Oxygen

Answer explanation

All group 1 metals will react in a similar way.

That's because they are all within the same group .They will all react by losing their outer electron and forming a positive ion.

Halogens belong to group...

• 5

• 6

• 7

• 8/0

As you go down group 1...

• The metals become more reactive

• The metals become less reactive

When sodium reacts with water, what do we see?

• An explosion!

• The sodium floats around and fizzes.

• The sodium fizzes then catches fire.

• The sodium turns into a sphere, fizzes and floats around the bowl.

Answer explanation

Sodium reacts so fast that a lot of heat is quickly produced. The sodium melts and forms a ball as it produces hydrogen.

When potassium catches on fire, the flame will be...

• Lilac

• Yellow-orange

• Green

• Brick red

Which of the following is the most reactive?

• Bromine

• Chlorine

• Iodine

• Fluorine

Bromine water is added to a potassium chloride solution. What happens?

• Nothing, Bromine is less reactive than Chlorine.

• Bromine is displaced and the solution turns orange-brown

• Potassium is displaced and the solution turns lilac

• Bromine displaces the chloride ion to form chlorine (pale green)

Answer explanation

Only a more reactive halogen (i.e. it is higher in the group, such as chlorine) can displace a halide (when the element is in a compound like potassium Bromide).

When chlorine displaces Iodine from potassium iodide, the solution turns...

• Pale green

• Orange brown

• It doesn't change colour

• lilac

Answer explanation

Chlorine is more reactive than Iodine so a displacement reaction will take place.

The colour change for the reactions you should know is always orange-brown.

Write the formula of the alkali made when potassium reacts with water.

(a)