Bonding, structure and properties

Question 1

Metallic bonding

Answer 1

the electrostatic force of attraction between positively charged ions and (negatively charged) delocalised outer electrons.

Question 2

How are atoms in covalent bonds held together?

Answer 2

By the electrostatic forces of attraction between positively charged nuclei and the negatively charged shared electrons

Question 3

What does the polarity of a covalent bond depend on?

Answer 3

On the difference in electronegativity of the bonded atoms

Question 4

Ionic bonding

Answer 4

electrostatic force of attraction between positively and negatively charged ions.

Question 5

what causes Van der Waals?

Answer 5

Electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms or molecules.

Question 6

Describe Van der Waals forces

Answer 6

Can operate between all types of molecules and atoms.
Are the weakest of all the other types of bonding.
Their strength depends on the sizes of the atoms or molecules.

Question 7

polar molecule:

Answer 7

molecule with a permanent dipole.

Question 8

what are permanent dipole-permanent dipole interactions?

Answer 8

they are additional electrostatic forces of attraction between polar molecules. they are stronger than VDW forces between molecules of the same size.

Question 9

the spatial arrangement of polar covalent bonds results in a molecule being…

Answer 9

polar.

Question 10

Between what elements can hydrogen bonding occur with?

Answer 10

Nitrogen, oxygen and fluorine

Question 11

Describe hydrogen bonding

Answer 11

Stronger than permanent dipole-permanent dipole interactions but weaker than covalent.
(el.st. forces of ) Attraction between molecules which contain highly polar covalent bonds.

Question 12

Describe a metallic structure

Answer 12

Lattice of positive ion and delocalised electrons

Question 13

Describe covalent molecular structure

Answer 13

Discrete molecules held together by weak intermolecular forces.

Question 14

Describe covalent network structure

Answer 14

A giant lattice of covalently bonded atoms.

Question 15

Describe ionic molecular structure

Answer 15

A giant lattice of oppositely charged ions.

Question 16

Describe monatomic structure

Answer 16

Discrete atoms held together by VDW forces.

Question 17

what does it mean if a molecule is discrete (don’t need to know for exam)

Answer 17

it is held together by VDW forces.

Question 18

compare melting and boiling points of polar molecules to those of non polar molecules.

Answer 18

The melting/boiling points are higher for polar molecules.

Question 19

What can these be related to?

• melting/boiling points
• hardness/softness

Answer 19

bonding and structures of elements

Question 20

What compounds are soluble in polar solutions such as water?

Answer 20

Polar molecular and ionic compounds.

Question 21

what is not soluble in water or polar compounds, but is in non-polar solutions?

Answer 21

Non-polar compounds.

Question 22

Give examples of anomalous boiling points due to hydrogen bonding.

Answer 22

Ammonia, water and hydrogen fluoride.

Question 23

Give 4 properties of compounds that are affected by hydrogen bonding.

Answer 23

higher boiling points and melting points, greater viscosity and miscibility with water.

Question 24

Why is the density of ice less than that of water?

Answer 24

Hydrogen bonding results in tunnels forming in the structure which are full of air.

Question 25

in what state is sulphur at room temperature?

Answer 25

Solid, 8 atoms bond together (discrete molecular solid)

Question 26

give another example of covalent molecular solid

Answer 26

Phosphorus (P4)

Question 27

are covalent molecular solids volatile? why?

Answer 27

yes, even if solid at room temperature. Because they have strong(er) intramolecular forces but intermolecular forces are very weak VDW.

Question 28

what happens between the layers of graphite?

Answer 28

there are free flowing electrons which make graphite able to conduct and flaky.

Question 29

what can you say about fullerenes?

Answer 29

under investigation- covalent molecular sructure

Question 30

why are metals malleable although their melting and boiling points are high?

Answer 30

because although the bonds are strong they are not directional.

Question 31

what forms a lattice, NOT a molecule?

Answer 31

Ionic compounds.

Question 32

give examples of covalent network structures

Answer 32

silicon carbide and silicon dioxide(quartz)

Question 33

a use of silicon carbide

Answer 33

abrasive in the cutting and grinding surfaces of tools

Question 34

which compounds conduct when molten?

Answer 34

Ionic compounds.