2.2.2 Bonding and Structure

Question 1

What is ionic bonding?

Answer 1

electrostatic attraction between positive and negative ions

Question 2

What is the structure of a giant ionic lattice?

Answer 2

regular repeating arrangement of lots of oppositely charged ions held together by strong ionic bonds/electrostatic forces of attraction

Question 3

Explain the trend in melting and boiling points of ionic compounds

Answer 3

they have high melting and boiling points due to the large amount of energy needed to break lots of strong ionic bonds

Question 4

Explain the trend in solubility of ionic compounds

Answer 4

solubility of an ionic compound depends on the relative strength of the electrostatic forces of attraction within the ionic lattice and the attractions between the ions and the polar molecule
in general the greater the ionic charge the less soluble the compound

Question 5

Explain the trend in electrical conductivity of ionic compounds

Answer 5

Ionic compounds can only conduct electricity when molten or dissolved because only then are the ions of the compound able to move and carry charge. Ionic compounds are unable to conduct electricity when solid because the ions are fixed in place and unable to carry charge.

Question 6

What is a covalent bond?

Answer 6

strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 7

What is a dative covalent bond?

Answer 7

a covalent bond where both of the shared electrons come from the same atom

Question 8

What is the shape and bond angle of a molecule with 2 bp and 0 lp of electrons and 2 br?

Answer 8

linear
180

Question 9

What is the shape and bond angle of a molecule with 3 bp and 0 lp of electrons and 3 br?

Answer 9

triagaonal planar
120

Question 10

What is the shape and bond angle of a molecule with 4 bp and 0 lp of electrons and 4 br?

Answer 10

tetrahedral
109.5

Question 11

What is the shape and bond angle of a molecule with 3 bp and 1 lp of electrons and 3 br?

Answer 11

pyramidal
107

Question 12

What is the shape and bond angle of a molecule with 5 bp and 0 lp of electrons and 5 br?

Answer 12

Triagonal bipyramidal
120 and 90

Question 13

What is the shape and bond angle of a molecule with 6 bp and 0 lp of electrons and 6 br?

Answer 13

octrahedral
90

Question 14

What is the shape and bond angle of a molecule with 2 bp and 2 lp and 2 br?

Answer 14

non linear
104.5

Question 15

Why are these shapes produced?

Answer 15

electron pairs repel as far as possible

Question 16

Which repel more lone pairs of electrons or bonded pairs of electrons?

Answer 16

lone pairs

Question 17

How does this affect bond angles?

Answer 17

reduces them

Question 18

What is electronegativity?

Answer 18

ability of an atom to attract a bonding pair of electrons towards itself in a covalent bond

Question 19

What is a polar bond?

Answer 19

when atoms of different electronegativities form covalent bonds creating a dipole moment (slightly positive charge and slightly negative charge at each end of molecule)

Question 20

What makes a molecule polar?

Answer 20

-precense of polar bonds
-asymmetry in the shape of the molecule (dipole charges do not cancel out)

Question 21

What is a permanent dipole-dipole interaction?

Answer 21

Occurs between polar molecules that have a permanent dipole due to a large difference in electronegativity

Question 22

What is an induced dipole-dipole interaction?

Answer 22

Occurs when temporary dipoles are induced in non-polar molecules due to the movement of electrons

Question 23

What are the conditions needed for hydrogen bonding?

Answer 23

1. Fluorine/Oxygen/Nitrogen atom
2. Lone pair of electrons on F/O/N
3. Hydrogen bonded to F/O/N

Question 24

What are the anomalous properties of ice caused by hydrogen bonding?

Answer 24

1. Relatively high melting and boiling points due to strong hydrogen bonds requiring a lot of energy to break
2. Ice is less dense than water (floats) due to open lattice structure (H-bonds hold water molecules apart)

Question 25

Why do simple molecular lattice structures have low melting and boiling points?

Answer 25

held together by weak intermolecular forces which do not require a lot of energy to overcome

Question 26

Why do simple molecular lattice structures not conduct electricity?

Answer 26

no delocalised electrons so cannot carry electrical current

Question 27

Why are simple molecular lattice structures non-soluble in water?

Answer 27

cannot form hydrogen bonds with water molecules