C3 structure and bonding

Question 1

What are the 3 states of matter?

Answer 1

Solid, Liquid and Gas

Question 2

What do these states of matter have?

Answer 2

Solids have a fixed shape and volume. Liquids have a fixed volume but can change shape. Gases have no shape or volume and can be compressed easily

Question 3

The hotter the gas, the

Answer 3

more faster the particles are and the more energetic and frequent the collisions are.

Question 4

What is the melting and boiling point?

Answer 4

The point that solid changes states to liquid and liquid to gas

Question 5

How does melting and boiling work

Answer 5

When hot, the particles get kinetic energy and start vibrating until they break of the bonds that keep them solid. In boiling the particles that vibrate due to the amount of kinetic energy and they break of the liquid and escape the surface and turn to gas

Question 6

The difference between boiling and evaporation?

Answer 6

In evaporation, particles leave a liquid from its surface only. In boiling, bubbles of gas form throughout the liquid. They rise to the surface and escape to the surroundings, forming a gas.

Question 7

The stronger the forces of attraction, the more?

Answer 7

energy is required to change state.

Question 8

Why in a cooling or heating curve graph as the substance is changing state or at the melting or boiling point the graph is flat lining?

Answer 8

The temperature doesn’t increase as all the energy is being used to change the state and not raise the temperature.

Question 9

What are ions?

Answer 9

An ion is an atom or group of atoms with a positive or negative charge
. Ions form when atoms lose or gain
electrons
to obtain a full outer shell:

metal
atoms lose electrons to form positively charged cations

non-metal
atoms gain electrons to form negatively charged anions

Question 10

What happens when forming positive ions?

Answer 10

Metal atoms lose electrons from their outer shell when they form ions:

the ions are positive, because they have more
protons
than electrons
the ions formed have full outer shells
the ions have the electronic structure of a noble gas (group 0 element), with a full outer shell
For elements in
groups
1, 2 and 3, the number of electrons lost is the same as the group number.

Question 11

Forming negative ions

Answer 11

The outer shells of non-metal atoms gain electrons when they form ions:

the ions formed are negative, because they have more electrons than protons
the ions have the electronic structure of a noble gas (group 0 element), with a full outer shell
For elements in groups 6 and 7, the charge on the ion is equal to (8 minus group number).

Question 12

What is an ionic bond?

Answer 12

Positive and negative ions form when a metal reacts with a non-metal, by transferring electrons
. The oppositely charged ions are strongly attracted to each other, forming
ionic bonds

Question 13

What are dot and cross diagrams?

Answer 13

A dot and cross diagram models the transfer of electrons from metal
atoms
to non-metal atoms. The electrons from one atom are shown as dots, and the electrons from the other atom are shown as crosses.

Question 14

What is an ionic lattice?

Answer 14

An ionic compound is a giant structure of ions. The ions have a regular, repeating arrangement called an ionic lattice
. The lattice is formed because the ions attract each other and form a regular pattern with oppositely charged ions next to each other.

Question 15

What is the force that holds them together?

Answer 15

An ionic lattice is held together by strong
electrostatic forces
of attraction between the oppositely charged ions. The forces act in all directions in the lattice.

Question 16

Why are the melting and boiling points of ionic compound so high?

Answer 16

the electrostatic forces of attraction between oppositely charged ions are strong

Question 17

When can an ionic compound conduct electricity?

Answer 17

it has melted to form a liquid, or it has dissolved in
water to form an aqueous solution. Both these processes allow ions to move from place to place. Ionic compounds cannot conduct electricity in the solid state because their ions are held in fixed positions and cannot move.

Question 18

What is a covalent bond?

Answer 18

A covalent bond is formed when two atoms share a pair of electrons. Covalent bonding occurs in most
non-metal elements, and in compounds formed between non-metals.

These shared electrons are found in the outer shells of the atoms. Usually each atom contributes one electron to the shared pair of electrons.

Question 19

What do intermolecular forces increase with?

Answer 19

The size of the molecules raising its melting and boiling point.

Question 20

What are polymers and their properties?

Answer 20

Polymers have very large
molecules. The atoms in a polymer molecule are joined together by strong
covalent bonds in long chains. There are variable numbers of atoms in the chains of a given polymer.

The intermolecular forces
between polymer molecules are strong compared to the intermolecular forces between small molecules. This means that polymers melt at higher temperatures than substances with small molecules. They are solids at room temperature.

Question 21

Graphite has a giant covalent structure in which?

Answer 21

-each carbon atom forms three covalent bonds with other carbon atoms
-the carbon atoms form layers of hexagonal rings
-there are no covalent bonds between the layers
-there is one non-bonded - or
delocalised
- electron from each atom

Question 22

What are the properties of graphite?

Answer 22

Graphite has delocalised electrons, just like metals. These electrons are free to move between the layers in graphite, so graphite can
conduct electricity. This makes graphite useful for
electrodes in batteries and for electrolysis.

The forces between the layers in graphite are weak. This means that the layers can slide over each other. This makes graphite slippery, so it is useful as a
lubricant.

Question 23

Explain why diamond does not conduct electricity and why graphite does conduct electricity.

Answer 23

Diamond does not conduct electricity because it has no charged particles that are free to move. Graphite does conduct electricity because it has delocalised electrons which move between the layers.

Question 24

What is metallic bonding?

Answer 24

Metals consist of giant structures of atoms arranged in a regular pattern.The electrons
from the outer shells of the metal atoms are
delocalised, and are free to move through the whole structure. This sharing of delocalised electrons results in strong
metallic bonding.

Question 25

What are the properties of metals?

Answer 25

-they are electrical
conductors because their delocalised electrons carry electrical charge through the metal
-they are good conductors of thermal energy because their delocalised electrons transfer energy
-they have high melting points and boiling points
, because the metallic bonding in the giant structure of a metal is very strong - large amounts of energy are needed to overcome the metallic bonds in melting and boiling
-They are also ductile and malleable as they have layers that can slide over each other.

Question 26

What are alloys?

Answer 26

An alloy is a mixture of two or more elements, where at least one element is a
metal. Many alloys are mixtures of two or more metals.

Question 27

Why are alloys made?

Answer 27

Many pure metals are too soft for many uses. They can be made harder by adding another element to the pure metal, so forming an alloy. This explains why an alloy often has more uses than the pure elements it is made from.

Pure iron, for example, is very soft. Adding a small amount of tungsten to iron makes tool steel, which is harder than pure iron.

Question 28

Why are alloys hard?

Answer 28

In the solid state, a pure metal has a giant metallic structure. The atoms are arranged in layers. When a
force is applied, the layers may slide over each other. The greater the force needed, the harder and stronger the metal.

In a pure metal, the force needed to make the layers slide over each other is small. This explains why many pure metals are soft.

In an alloy, there are atoms of different sizes. The smaller or bigger atoms distort the layers of atoms in the pure metal. This means that a greater force is required for the layers to slide over each other. The alloy is harder and stronger than the pure metal.

Question 29

What are nanoparticulate materials?

Answer 29

A substance that consists of nanoparticles
is described as being
nanoparticulate.

Some properties of nanoparticulate materials are different from the properties of the same material in bulk, as powders, lumps or sheets. This difference in properties is the result of two things:

-the tiny size of nanoparticles compared to the same material in bulk
-the large
surface area
to
volume
-ratios of nanoparticulate materials compared to the same material in bulk

Question 30

What do they do?

Answer 30

The large surface area to volume ratios of nanoparticulate substances allows them to act as catalysts. Compared to the same substances in bulk, they may:

-catalyse reactions more efficiently
-catalyse different reactions that produce different
products

Question 31

What are some people concerned with nanoparticles?

Answer 31

explosions caused by sparks,
health problems if breathed in
if nanoparticles escape into air / environment