Period 3

Question 1

How are the blocks arranged in the periodic table?

Answer 1

S D P F

Question 2

What is the characteristic of a transition meta/.

Answer 2

Form a compound in which they have a partially filled d-orbital.

Question 3

Do metals get more or less reactive going down a group?

Answer 3

More

Question 4

Do non-metals get more or less reactive going down the group?

Answer 4

Less

Question 5

Why do the melting and boiling points of the metals from sodium to aluminium in period three increase?

Answer 5

From left to right the charge on the ion increases so there are more delocalised electrons and stronger metallic bonding.

Question 6

Why does silicon have the highest boiling point?

Answer 6

Because of its giant structure.

Question 7

Why does the atomic radius decrease across period three?

Answer 7

No new shells are formed, nuclear charge increases so electrons are pulled closer in.

Question 8

What is first ionisation energy?

Answer 8

The amount of energy required to convert a mole of gaseous atoms to a mole of gaseous ions with a single + charge.

Question 9

Why does the first ionisation energy increase across a period?

Answer 9

Nuclear charge increases but no new shells are started so it becomes increasingly difficult to remove one electron.

Question 10

Why does first ionisation energy decrease going down a group?

Answer 10

Increased shielding and increased distance from nucleus so easier to remove.

Question 11

Why does the atomic radius increase going down a group?

Answer 11

The atoms of each element have an extra shell of electrons compared to the one before.

Question 12

Why is there a drop in ionisation energy from neon to sodium?

Answer 12

A new main energy level is started so there is an increase in atomic radius and shielding so the electron is easier to remove.

Question 13

Why is there a drop in first ionisation energies between Magnesium and Aluminium.

Answer 13

Aluminium’s outer electron is in a 3p shell unlike magnesium which is in £s shell. 3p electron is easier to remove due to shielding.

Question 14

Why is there a drop in first ionisation energy between phosphorus and sulfur?

Answer 14

Because sulfur has 2 electrons paired in its outer orbital, one of these is easier to remove than on on its own due to electron repulsion.

Question 15

How does sodium react with water?

Answer 15

2Na + 2H2O –> 2NaOH + H2

Question 16

What is the equation for magnesium reacting with water/steam?

Answer 16

Mg + 2H2O –> MgOH2 + H2

Question 17

Why does magnesium reacting with water produce a less alkaline solution than sodium reacting with water?

Answer 17

Because magnesium hydroxide is barely soluble.

Question 18

Which elements react directly with oxygen? What do the metals produce, what do the non-metals produce?

Answer 18

Sodium to sulfur.
Metals produce basic oxides.
Non-metals produce acidic oxides.

Question 19

Give the equation for sodium reacting with oxygen. How would you carry out the experiment?

Answer 19

2Na +1/2O2 –> 2NaOH

Place hot sodium in a jar of oxygen.

Question 20

Give the equation for magnesium reacting with oxygen. How would you carry out the experiment?

Answer 20

Mg + 1/2O2 –> MgO

Place burning magnesium ribbon in a gar of oxygen.

Question 21

Give the equation for aluminium reacting with oxygen. How would you carry out the experiment?

Answer 21

4Al + 3O2 –> 2Al2O3

Sprinkle aluminium powder into a bunsen burner fame.

Question 22

Give the equations for silicon, phosphorus and sulfur reacting with oxygen.

Answer 22

• Si + O2 –> SiO2
• 4P + 5O2 –> P4O10
• S + O2 –> SO2

Question 23

What forms in the reaction between oxygen and phosphorus if the oxygen supply is limited?

Answer 23

Some P2O3 is formed.

Question 24

How does the structure of period 3 oxides change going across from left to right?

Answer 24

Giant Ionic > macromolecular > Simple covalent.

Question 25

Why does the bonding in aluminium oxide have covalent character?

Answer 25

High charge:size ratio can distort the electron cloud around the O^2- ion.

Question 26

Which two oxides of period 3 are insoluble?

Answer 26

Aluminium oxide and silicon dioxide.

Question 27

Give the equations for the oxides of period 3 reacting with water.

Answer 27

• Na2O + H2O –> 2NaOH
• MgO + H2O –> Mg(OH)2
• P4O10 + 6H2O –> 4H3PO4
• SO2 + H2O –> H2SO3
• SO3 + H2O –> H2SO4

Question 28

Why is aluminium oxide insoluble in water?

Answer 28

Bonding in aluminium oxide is too strong for the lattice to dissociate.

Question 29

What happens when the ionic period 3 oxides dissolve in water?

Answer 29

They first produce O^2- ions which are strong bases and react with water to form an alkaline solution.

Question 30

Are the oxides of sodium and magnesium basic or acidic?

Answer 30

Basic

Question 31

Are the oxides of silicon, phosphorus and sulfur acidic or basic?

Answer 31

Acidic

Question 32

Which oxide of period three is amphoteric?

Answer 32

Aluminium.

Question 33

Give equations for how sodium and magnesium oxides react with acids.

Answer 33

Na2O + 2HCl –> 2NaCl + H2O

MgO + H2SO4 –> MgSO4 + H2O

Question 34

Give equations to show how aluminium reacts with an acid and a base.

Answer 34

Al2O3 + 6HCl –> 2AlCl3 + 3H2O

Al2O3 + 2NaOH + 3H2O –> 2NaAl(OH)4

Question 35

Give equations to show how silicon dioxide react with a base?

Answer 35

• SiO2 + NaOH –> Na2SiO3 + H2O (sodium silicate)

Question 36

How does phosphorus pentoxide react with a base?

Answer 36

• Phosphorus pentoxide reacts first with water to form phosphoric acid. Then: 3KOH + H3PO4 –> K3PO4 + H2O

Question 37

How does Sulfur dioxide react with a base?

Answer 37

• SO2 + NaOH –> NaHSO3

NaHSO3 + NaOH –> Na2SO3 + H2O