2. Bonding and structure ( IONIC)

Question 1

What is ionic bonding

Answer 1

The strong electrostatic attraction between 2 oppositely charged ions

Question 2

What structure do ionic compounds form

Answer 2

Giant ionic lattices

Question 3

What is ionic bonding formed from

Answer 3

The transfer of electrons between metals and non metals in order to gain a full outer shell

Question 4

Give 4 properties of ionic compounds

Answer 4

High melting and boiling points
Brittle and easily cleaved
Soluble in water
Conduct electricity when molten or aqueous

Question 5

Explain why ionic compounds are brittle

Answer 5

They are brittle because when the ions are forced out of position, like charges line up and cause repulsion and cracking of the ionic compound.

Question 6

Explain why an Na ion has a 1+ charge

Answer 6

The atom has lost an electron so there is now 10 electrons but still 11 protons so an overall 1+ charge

Question 7

How do ions size change compared to their atoms

Answer 7

• positive ions (cations) get smaller
• negative ions (anions) get bigger

Question 8

Give 2 main properties that affect the strength of electrostatic attraction in ionic compounds so therefore the melting point

Answer 8

Size of the charge - greater charge = stronger electrostatic force of attraction (more energy required to overcome..)

Ionic radius (size of ion) - smaller sized ions packed more closely = stronger electrostatic attraction

–> smaller sized ion + greater charge = high charge density

Question 9

Trends in ionic radii for isoelectric ions

Answer 9

• same number of electrons yet differing proton numbers
• as proton number increases the ionic radius decreases as there is a greater nuclear charge on the same amount of electrons

Question 10

Trends in ionic radii (down the group)

Answer 10

The ionic radius increases down a group as there are more electron shells

Question 11

Give an experiment to show the evidence for charged particles

Answer 11

Electrolysis of copper (II) chromate (IV)
chopper chromate solution = green
when a current is passed through solution:
BLUE Cu 2+ ions = attracted to negative cathode
YELLOW CrO4 2- ions = attracted to positive anode

Question 12

What is water of crystallisation

Answer 12

When a compound contains water molecules bonded into the crystal structure

Question 13

How is water of crystallisation shown in a compound

Answer 13

Shown using a dot
Eg - CaSO4.2H20

Question 14

What is a hydrated compound

Answer 14

A compound that contains water of crystallisation

Question 15

What does an anhydrous compound mean

Answer 15

It does not contain water of crystallisation as it has been heated so the bonds have been broken and the water has been removed as steam

Question 16

Describe how you would work out the value of water of crystallisation from the mass of the hydrated compound and anhydrous compound
—> MGSO4.xH20

Answer 16

—> use the same method as empirical formula

1) subtract the mass of hydrated compound away from anhydrous compound to work out mass of water (first one subtract second )

2) work out the number of moles of anhydrous compound and moles of water

3) divide both moles by the smallest number of moles to get a ratio