Structure And Bonding

Question 1

What are the three types of bonding

Answer 1

Covalent bonding
Ionic bonding
Metallic bonding

Question 2

What is ionic bonding

Answer 2

Involves an attraction between oppositely charged ions. Found in compounds
Metal atoms lose electrons to become positively charged ions
Non metals gain electrons to become negatively charged ions

Question 3

What is covalent bonding

Answer 3

Formed when 2 non metal atoms share pairs of electrons. Strong because the shared electrons are attracted to the nucleus of both atoms

Question 4

What is metallic bonding

Answer 4

Involves an attraction between positively charged ions and negatively charged delocalised electrons

Question 5

What are examples of covalent molecules

Answer 5

Small molecules- eg water
Large molecules- eg polyester
Giant covalent structures- eg diamond

Question 6

What are the advantages and limitations of dot and cross diagrams

Answer 6

Shows the pairs of outer electrons and which atoms theyve come from
Doesn’t show how the atoms are arranged in space

Question 7

What are the advantages and limitations of a ball and stick diagram

Answer 7

Fails at indicating movement of electrons
Also 2D

Question 8

What are the properties of solids

Answer 8

Particles are very close and vibrate at a fixed position
Fixed shape and volume
When heated the particles vibrate with a greater amplitude

Question 9

What are the properties of liquids

Answer 9

Particles are close together but they move and flow randomly
Have fixed volume but can change shape
When heated the average speed of particles increases

Question 10

What are the properties of gases

Answer 10

Particles are far apart and move randomly in all directions
Gases change shape and volume
Negligible forces

Question 11

What are the disadvantages to the “simple sphere” model

Answer 11

Forces between the particles aren’t shown as a result it’s impossible to know how strong these forces are and how much energy is needed
Portrays particles in a spherical way but they arnt
Portrays particles as solid when they arnt

Question 12

What happens when particles gain or lose energy

Answer 12

Because of heating/cooling-they overcome or submit to the forces of other particles which causes them to change shape

Question 13

What are the 4 types of state changes

Answer 13

Melting- (s-l)
Condensing- (g-l)
Boiling-(l-g)
Freezing-(l-s)

Question 14

What happens with stronger forces

Answer 14

Stronger forces between particles means more energy is required to overcome those forces. They have higher melting and boiling points

Question 15

What happens with weaker forces

Answer 15

Weaker forces between particles means less energy is required to overcome those forces. Have lower melting and boiling points

Question 16

What does aq mean as a state symbol

Answer 16

Aqueous solutions (substances dissolved in water)

Question 17

What are the properties of ionic compounds

Answer 17

High melting and boiling points- lots of energy is needed to overcome the electrostatic forces between the ions and electrons in the lattices
Because if this they have high melting and boiling points

Question 18

Properties of ionic compounds (2)

Answer 18

Cannot conduct electricity when solid-when solid the ions in the lattice are fixed in place . TMT changes cannot flow so electricity can’t be conducted
Can conduct electricity when liquid-when dissolved in liquid the ions in the lattice are free to move because of this charge can flow and electricity can be conducted

Question 19

Why do small covalent molecules have low melting and boiling points

Answer 19

. Intermolecular forces are much weaker than the strong covalent bonds in molecules. When small molecular substances melt or boil, it is these weak intermolecular forces that are overcome. The covalent bonds are not broken. Relatively little energy is needed to overcome the intermolecular forces, so small molecular substances have low melting and boiling points.

Question 20

Why do bigger molecules have higher melting and boiling points

Answer 20

Because the smaller the molecule, the weaker the intermolecular forces.

Question 21

Why don’t small or big covalent molecules conduct electricity

Answer 21

They cannot conduct electricity because they do no have an overral electric charge

Question 22

Why are polymers solid at room temperature

Answer 22

They have very large molecules. Atoms in the polymer molecules are linked to other atoms by strong covalent bonds. Intermolecular forces between polymer molecules are relatively strong and require a lot of energy to overcome them

Question 23

What are the properties of Giant Covalent structures

Answer 23

No specific formula-because the structure can be any size
Very high melting points- because of strong covalent bonds
1 large molecule-Giant covalent structures exist as 1 large molecule. Means there are no intermolecular forces

Question 24

What are examples of giant covalent structures

Answer 24

Diamond
Graphite
Graphene
Fullerenes

Question 25

What are the properties of pure metals

Answer 25

High melting and boiling points-strong electrostatic forces between metal ions and delocalised electrons and giant structures of atoms Soft and malleable-because the ions are arranged in layers they Slide Over eachother and be bent and shaped. This means they are too soft and should be mixed with other metals to make alloys which are harder

Question 26

What are metals as conductors like

Answer 26

Good conductors of electricity because the delocalised electrons in the metal carry electrical charge through it Good conductors of heat because energy is transferred by the delocalised electrons

Question 27

What are alloys

Answer 27

A mixture is 2+ elements where at least one is a metal

Question 28

Why are alloys harder than metals

Answer 28

The different sized atoms distort the layer making them harder to Slide Over eachother. However the ions in metals are arranged in layers so they Slide Over eachother easily

Question 29

What are the properties of diamond

Answer 29

Doesn’t conduct electricity-because there are no delocalised electrons in its structure (bonded to 4 carbon atoms) High melting point and is very hard- has lots of strong covalent bonds making it hard and having a high melting point

Question 30

What are the properties of graphite

Answer 30

Soft-carbon atoms form layers of hexagonal rings with each layer held together by weak intermolecular forces. Layers Slide Over and have no covalent bonds between the layers so it’s very soft Conducts electricity-it is bonded to 3 carbon atoms which means that there is 1 delocalised electron which moves freely to carry the charge

Question 31

What are the properties of Graphene

Answer 31

Conducts electricity-single layer of graphite so it also conducts electricity Light but strong-Graphene is 1 layer thick. Makes it light however the atoms within the layers are tightly bonded and elastic because the planes of atoms can flex relatively easily without the atoms breaking Useful in electronics and composites

Question 32

What was the first fullerene to be discovered and properties

Answer 32

Buckminster fullerene Molecules of carbon atoms with hollow shapes Based on hexagonal rings of carbon atoms but they may also contain rings with 5 or 7 carbon atoms

Question 33

What is the formula of buckminster fullerene

Answer 33

C60

Question 34

What are the common uses of these fullerenes

Answer 34

Catalysts Lubricants Delivering drugs into the body

Question 35

What are the properties of carbon nanotubes

Answer 35

Cylindercal fullerenes with very high length to diameter ratios

Question 36

What are the uses of carbon nanotubes

Answer 36

Nanotechnology, electronics and materials

Question 37

What is the structure of sodium chloride

Answer 37

Na+ and Cl-

Question 38

What are the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane

Answer 38

H2, HCl, O2, Cl2, NH3 and CH4

Question 39

How does particle theory help to explain melting boiling freezing and condensing

Answer 39

The amount of energy needed to change state from a solid to liquid and from liquid to gas depends on the strength of the forces between particles The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting and boiling point