1.3 Bonding

Question 1

What is ionic bonding

Answer 1

Strong electrostatic forces of attraction between oppositely charged ions held in lattice

Question 2

Give an example of an ionically bonded substance

Answer 2

NaCl

Question 3

How high are ionically bonded substances bp and mp? Why?

Answer 3

High as it takes lots of energy to break strong electrostatic forces of attraction between oppositely charged ions

Question 4

Do ionic compounds conduct electricity? why?

Answer 4

Yes when molten/in solution as the ions are free to move and carry charge (don’t when solid)

Question 5

What is simple molecular covalent bonding?

Answer 5

Strong covalent bonds between atoms, weak VDW forces of attraction between molecules

Question 6

Are there any lone electrons in simple covalent bonding?

Answer 6

No - all involved in bonding

Question 7

Can simple molecular covalent molecules conduct electricity? Why?

Answer 7

No all electrons used in bonding and aren’t free to move

Question 8

Do simple molecular substances have a high/low mpt and bpt? Why?

Answer 8

Low- weak VDW forces of attraction between molecules that don’t take much energy to overcome (these are overcome rather than covalent bonds)

Question 9

Describe macromolecular covalent bonding

Answer 9

Lattice of many atoms held together by strong covalent bonds

Question 10

Do substances with macromolecular covalent bonds have high/low mpt and bpts? Why?

Answer 10

High, as it takes a lot of energy to overcome many strong covalent bonds

Question 11

Do substances with macromolecular covalent bonds conduct electricity?

Answer 11

Most don’t as all electrons are used in bonding

Question 12

Draw and describe structure of a diamond

Answer 12

3D tetrahedral structure of C atoms , with each C atom bonded to four others

Slide 26

Question 13

Draw and describe structure of graphite

Answer 13

Similar to diamond - macromolecular covalent- but each C atom is only bonded to 3 others, so it is in layers

Weak VDW forces of attraction between layers mean they can slide over each other —> soft, slippery

One electron from each carbon is delocalised and can carry charge —> conducts electricity

Question 14

Describe and draw metallic bonding

Answer 14

Lattice of positive metal ions strongly attracted to a sea of delocalised electrons.

Layers can slide over each other - malleable

Question 15

Do metallic compounds have high/low bpt and mpts? Why?

Answer 15

High as strong forces of attraction between positive metal ions and negatively charged sea of delocalised electrons

Question 16

Do metallic compounds conduct electricity? Why?

Answer 16

Yes as delocalised electrons can move throughout the metal to carry charge

Question 17

How does the strength of metallic bonds change across the periodic table? Why?

Answer 17

Increases —> higher melting and boiling points, stronger

Higher charge on metal ions

More delocalised electrons per ion

Stronger forces of attraction between them

Question 18

Define electronegativity

Answer 18

The ability of an atom to attract the pair of electrons (electron density) in a covalent bond

Question 19

What affects electronegativity

Answer 19

Nuclear charge

Atomic radius

Electron shielding

Question 20

What is the most electronegative element?

Answer 20

Fluorine as it has the largest nuclear charge for its electron shielding, small atomic radius

Question 21

How do you get a non polar bond?

Answer 21

Both bonding elements have the same electronegativities

Question 22

When do you get a polar bond?

Answer 22

Bonding atoms have different electronegativities

Question 23

What is the strongest type of inter-molecular force?

Answer 23

Hydrogen bonding

Question 24

What is the weakest type of inter-molecular force?

Answer 24

VDW forces

Question 25

Describe VDW forces of attraction

Answer 25

Temporary dipoles are created by the random movement of electrons —> induces dipole in neighbouring molecules —> temporary induced dipole-dipole attraction aka VDW forces of attraction

Question 26

Are VDW forces greater in smaller or larger molecules?

Answer 26

Larger - more electrons

Question 27

Describe permanent dipole-dipole attraction

Answer 27

Some molecules with polar bonds have permanent dipole —> forces of attraction between those dipoles and those of neighbouring molecules

Question 28

What conditions are neeeded for hydrogen bonding to occur?

Answer 28

O-H, N-H, F-H bond, lone pair of electrons on O,F,N Because O,N,F are highly electronegativite, H nucleus is left exposed Strong forces of attraction between H nucleus and lone pair of electrons on O, N, F

Question 29

Draw a diagram of hydrogen bonding

Answer 29

Slide 60

Question 30

Why is ice less dense than liquid water?

Answer 30

In liquid water, hydrogen bonds constantly break and reform as molecules move about In ice the hydrogen bonds hold the molecules in fixed positions this makes them slightly further apart than in liquid water

Question 31

What is a dative/Co-ordinate covalent bond? When is it formed?

Answer 31

Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone pair of electrons (not used in bonding)

Question 32

Draw the formation of a dative covalent bond in ammonia

Answer 32

Slide 65

Question 33

What does the shadow of molecules depend on?

Answer 33

Number of electrons in the valence shell of the central atom Number of these electrons which are on bonded or lone pairs

Question 34

What does the electron pair repulsion theory state?

Answer 34

That electrons pairs will take up positions as far away from each other as possible, to minimise the repulsive forces between them

Question 35

Which experience the most repulsion? Lone pair - lone pair Bonded pair - bonded pair Lone pair - bonded pair

Answer 35

LP- LP repulsion strongest LP-BP repulsion middle BP-BP repulsion weakest

Question 36

What is the shape, diagram and bond angle in a shape with 2 bonded pairs and 0 lone pairs?

Answer 36

Linear 180

Question 37

What is the shape, diagram and bond angle in a shape with three bonding pairs and 0 lone pairs?

Answer 37

Trigonal planar 120

Question 38

What is the shape diagram and bond angle in a shape with 4 bonded pairs and 0 lone pairs?

Answer 38

Tetrahedral 109.5

Question 39

What is the shape diagram and bond angle in a shape with 5 bonded pairs and 0 lone pairs?

Answer 39

Trigonal bipyramid 90 and 120

Question 40

What is the shape diagram and bond angle in a shape with 6 bonded pairs and 0 lone pairs?

Answer 40

Octahedral 90