1.2) Bonding, Structure and Properties of Matter

Question 1

positive / negative / bigger / smaller / shell

1) Atoms need a full outer _____ of electrons in order to be stable. One way they can achieve this is by gaining or losing electrons.

2) Those that gain electrons become ions with a ________ charge, whilst those that lose electrons become ions with a _______charge.

Answer 1

1) shell

2) negative, positive

Question 2

Magnesium loses electrons to become an ion. Complete the equation below:

_____ ➔ Mg2+ + ______ e-

Answer 2

Mg ➔ Mg2+ + 2e-

Question 3

What type of ion do elements from each of the following groups form ?
a) Group 1
b) Group 7

Answer 3

a) group 1 metals lose ions to form positive ions (cations)
b) group 7 non-metals gain electrons to from negative ions (anions)

Question 4

Describe how an ionic bond forms

Answer 4

When a non-metal and metal react together, the metal atom loses electrons to from a positively charged ion and the non-metal gains these electrons to form a negatively charged ion.
These oppositely charged ions are strongly attracted to one another by ELECTROSTATIC forces.

Question 5

show a dot and cross diagram of sodium chloride

Answer 5

Question 6

show a dot and cross diagram of magnesium oxide

Answer 6

Question 7

show a dot and cross diagram of magnesium chloride

Answer 7

Question 8

show a dot and cross diagram of sodium oxide

Answer 8

Question 9

Describe the structure of a crystal of sodium chloride

Answer 9

A single crystal of sodium chloride (table salt) is one giant ionic lattice. The Na+ and Cl- ions are held together in a regular lattice. The lattice can be represented in different ways….(e.g. ball and stick models)

Question 10

List the main properties of ionic compunds

Answer 10

• They all have high melting points due to the many strong bonds between the ions.
• When they are solid the ions are held in place, so the compounds cant conduct electricity. When ionic bonds melt the ions are free to move and they’ll carry electric current.
• Some ionic compounds also dissolve in water. The ions separate and are all free to move in the solution, so they’ll carry electric current.

Question 11

Describe how covalent bonds are formed.

Answer 11

When no-metal atoms bond together, they share pairs of electrons to make covalent bonds.
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces, making covalent bonds very strong

Question 12

show a dot and cross diagram that shows the bonding in a molecule of hydrogen

Answer 12

Question 13

show a dot and cross diagram that shows the bonding in a molecule of water

Answer 13

Question 14

show a dot and cross diagram that shows the bonding in a molecule of hydrogen chloride

Answer 14

Question 15

Explain why simple molecular compounds typically have low melting and boiling points

Answer 15

To melt or boil a simple molecular compound, you only need to break these feeble intermolecular forces and not the covalent bonds. So the melting and boiling points are very low, because the molecules are easily parted from each other.

Question 16

Describe the structure of a polymer.

Answer 16

Lots of small units are linked together to form a long molecule that has repeating sections. All the atoms in a polymer are joined by strong covalent bonds.

Question 17

Give three examples of Giant covalent substances

Answer 17

Diamond
Graphite
Silicon Dioxide

Question 18

Explain why graphite can conduct electricity.

Answer 18

Only three out of each carbon’s four outer electrons are used in bonds, so each carbon atom has one electron that’s delocalized (free) and can move. So graphite conducts electricity and thermal energy.

Question 19

Explain how fullerenes could be used to deliver drugs into the body.

Answer 19

Fullerenes can be used to ‘cage’ other molecules. The fullerene structure forms around another atom or molecule, which is then trapped inside. This could be used to deliver a drug into the body.

Question 20

What is metallic bonding?

Answer 20

(Metallic bonding involves delocalized electrons.)
- Metals also consist of a giant structure
- The electrons in the outer shell of the metal atoms are delocalized. There are strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons.
- These forces of attraction hold the atoms together in a regular structure and are known as metallic bonding. Metallic bonding is very strong.
- Substances that are held together by metallic bonding include metallic elements and alloys
- Its the delocalized electrons in the metallic bonds which produce all the properties of metals.

Question 21

List three properties of metals and explain how metallic structure causes each property.

Answer 21

MOST METALS ARE SOLID AT ROOM TEMPERATURE:
- The electrostatic forced between the metal atoms and the delocalized sea of electrons are very strong, so need lots of energy to be broken
- This means that most compounds with metallic bonds have very high melting and boiling points, so generally they are solid at room temperature.
METALS ARE GOOD CONDUCTORS OF ELECTRICITY:
- The delocalized electrons carry electrical current and thermal energy through the whole structure, so metals are good conductors of electricity.
MOST METALS ARE MALLEABLE:
- The layers of atoms in a metal can slide over each other, making metals malleable - this means that they can be bent or hammered or rolled into flat sheets.

Question 22

Explain why alloys are harder then pure metals

Answer 22

Pure metals often aren’t quite right for certain jobs - they are often too soft when they are pure so are mixed with other metals to make them harder.
( 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 23

Name three states of matter

Answer 23

Solid
Liquid
Gas

Question 24

What is another name for positive ions?

Answer 24

cations

Question 25

What is the term for the temperature at which a solid changes into a liquid?

Answer 25

The temperature at which a solid converts into a liquid is called the melting point.

Question 26

What is the term for the temperature at which a liquid changes into a gas?

Answer 26

The temperature at which a liquid converts into a gas is called the boiling point.

Question 27

Strong forces of attraction between particles:

Answer 27

Solid

Question 28

Weak forces of attraction between particles:

Answer 28

Liquid

Question 29

Very weak forces of attraction between particles:

Answer 29

Gas

Question 30

What are nanoparticles ?

Answer 30

• Nanoparticles have a very high surface area to volume ratio.
• This means they make very good catalysts in chemical reactions.