Groups In The Periodic Table

Question 1

What are the group 1 metals known as?

Answer 1

The alkali metals

Question 2

How many electrons do they have in their outer shells?

Answer 2

They all have 1electron in their outer shell (so they have similar chemical properties)

Question 3

List the physical properties of the alkali metals

Answer 3

Low melting and boiling points (compared to other metals)
Very soft (they can be cut with a knife)

Question 4

What do they form when they react with other elements?

Answer 4

Ionic compounds (they lose their outer electron very easily so there’s no need to share it)

Question 5

How reactive are group 1 metals? Why is this?

Answer 5

Very reactive- the group 1 metals readily lose their outer electron to form a 1+ ion with a stable electron structure

Question 6

Describe the reactivity trend of the group 1 metals- why is this the case?

Answer 6

Get more reactive as you descend the group- the outer electron is more easily lost because it has a larger atomic radius (the outer electron gets further from the nucleus) so it is less strongly attracted and less energy is needed to remove it. The reactions also get more violent because of this.

Question 7

What occurs when an alkali metal reacts with water?

Answer 7

When put in water, they react vigorously, producing hydrogen gas and a hydroxide of the metal

Question 8

Give an example for the equation for the reaction of an alkali metal with water

Answer 8

Sodium with water:
2Na + 2H20 / 2NaOH + H2
Sodium + water / sodium hydroxide + hydrogen

Question 9

How does lithium react with water?

Answer 9

Moves around the surface, fizzing furiously

Question 10

How does sodium react with water?

Answer 10

Moves around the surface, fizzing furiously. It also melts in the heat of the reaction.

Question 11

How does potassium react with water?

Answer 11

Moves around the surface, fizzing furiously. It also melts in the heat of the reaction, and gets so hot it ignites the hydrogen gas being produced.

Question 12

How do rubisum and cesium react with water?

Answer 12

React violently, and tend to explode in water.

Question 13

What are the group 0 elements called?

Answer 13

The noble gases

Question 14

What do the noble gases look like at room temperature?

Answer 14

Colourless gases

Question 15

Are noble cases made up of single atoms, or molecules?

Answer 15

Single atoms (they are monatomic)

Question 16

How reactive are the noble gases? Why?

Answer 16

Inert- they have a full outer shell of electrons, so dont easily give up or gain electrons. (This makes them non-flammable)

Question 17

Why did the noble gases take a long time to be discovered?

Answer 17

Because they were inert it made them hard to observe

Question 18

State the uses of noble gases

Answer 18

The noble gases can be used to provide an inert atmosphere

• argon does this in filament lamps. Since it’s non-flammable, its stops the hot filament burning away.
• this is the same in flash photography- argon, krypton and xenon are used to stop the flash filament burning up during hgih temperature flashes.
• argon and helium protect metals being welded. The inert atmosphere stops the hot metal reacting with oxygen.
• helium is used in airships and party balloons.

Question 19

Why is helium used in balloons?

Answer 19

Helium has a lower density than air, making balloons float. It is also non-flammable so its safer to use than hydrogen gas.

Question 20

Describe the trends of physical properties as you descend the noble gases

Answer 20

Boiling point, melting point and density all increase.

Question 21

Why do elements in the same group react in similar ways?

Answer 21

They all have the same number of electrons in their outer shells

Question 22

How would youclauclate the density of neon, from the densities of helium and argon?

Answer 22

Neon is between helium and argon in the group, so its density will be roughly halway between their densities. (Add up their densities, then divide by 2)

Question 23

What are the group 7 elements known as?

Answer 23

The halogens

Question 24

How do you test for chlorine gas?

Answer 24

Hold a piece if damp blue litmus paper over it. Chlorine will bleach the litmus paper white. It may also turn red momentarily because a solution for chlorine is acidic

Question 25

Describe the reactivity trend change as you descend group 7

Answer 25

The halogens become less reactive- it gets harder to attract the extra electron needed to fill the outer shell when it has a larger atomic radius (the outer shell is farther away from the nucleus)

Question 26

How do the halogens react?

Answer 26

Need to gain 1 electron to form a 1- ion with a stable electron structure

Question 27

What molecules do the halogens exist as?

Answer 27

Diatomic molecules (e.g. Cl2, Br2, I2), and so share one pair of electrons in a covalent bond, giving both atoms a full outer shell.

Question 28

How do the melting and boiling points change as you decend group 7?

Answer 28

They increase

Question 29

What do the halogens look like at room temperature?

Answer 29

Chlorine (Cl2)- a fairly reactive, poisonous green gas.
Bromine (Br2)- a poisonous, red-brown liquid, which give off an orange vapour at room temp.
Iodine (I2)- a dark grey crystalline solid, whcin gives off a purple vapour when heated.

Melting point increases, and the colours of the halogens become darker as you go down the group (astatine is a black solid with a melting point of around 300 degrees c)