Structure and bonding

Question 1

What is the definition for ionic bonding?

Answer 1

An ionic bond is an electrostatic attraction between oppositely charged ions.

Question 2

What charge does an ion have if it looses two electrons?

Answer 2

A charge of plus two.

Question 3

What charge does an ion have if it gains an electron?

Answer 3

A charge of negative one.

Question 4

What is the name of the diagram given to ion diagrams?

Answer 4

A dot and cross diagram

Question 5

What is an ionic compound made up of?

Answer 5

An ionic compound is made up of a positive metal ion and a negative non-metal ion.

Question 6

What is the structure of an ionic compound? (three things)

Answer 6

Ionic compounds have a crystalline structure because the ions are arranged in a giant lattice. This lattice has a regular arrangement of ions.

Question 7

Why do ionic compounds have high melting points?

Answer 7

Ionic compounds have a high melting point because there are strong electrostatic forces of attraction between oppositely charged ions. This means the bonds in the giant lattice are hard to break.

Question 8

Why can ionic compounds conduct electricity?

Answer 8

Ionic compounds conduct electricity when dissolved in water because the ions are free to move. These ions carry the electric charge.

Question 9

True or false, a sodium atom can only form one ionic bond.

Answer 9

False. Each atom can form many different ionic bonds.

Question 10

What is covalent bonding?

Answer 10

In covalent bonding, atoms share pairs of electrons in order to achieve a full outer shell.

Question 11

What two words lead you to think of a covalent bond?

Answer 11

Atom or Molecule.

Question 12

What type of structure are simple covalent substances?

Answer 12

Non-crystalline

Question 13

Why to simple covalent substances have low melting and boiling points?

Answer 13

Covalent substances have low melting and boiling points because of weak intermolecular forces.

Question 14

Do covalent substances conduct electricity? Why?

Answer 14

No. There are no charged particles.

Question 15

Explain relating to the structure of diamond why it is used in drills.

Answer 15

Diamond is used in drills because it is very hard. It is very hard because it has strong covalent bonds. This means that each carbon atom is joined to four other carbon atoms. As a result, it won’t break.

Question 16

Why does diamond have a high melting point?

Answer 16

Diamond has a high melting point because each atom is joined to four other carbon atoms forming strong covalent bonds.

Question 17

Does diamond conduct electricity? Why?

Answer 17

Diamond doesn’t conduct electricity because there are no delocalised electrons.

Question 18

Graphite is a good lubricant. Explain in terms of it’s structure why.

Answer 18

Graphite is a very good lubricant because it is soft and slippery. Atoms are arranged in layers which can slip and slide over each other. There are weak forces of attraction between the layers.

Question 19

Why does graphite conduct electricity?

Answer 19

Graphite conducts electricity because each carbon atom is joined to three other carbon atoms. This results in electrons not being used in bonding. These delocalised electrons can move through the substance creating an electrical current.

Question 20

What property does the strong covalent bonds give graphite?

Answer 20

A high melting point.

Question 21

What is an allotrope?

Answer 21

An allotrope is a different substance made of the same atoms.

Question 22

Buckminsterfullerene is an allotrope of carbon and has the formula of…

Answer 22

C6O

Question 23

Silicon dioxide (sand) is a giant covalent structure and it has a high melting point. Why?

Answer 23

Because the atoms are held together with strong covalent bonds.

Question 24

What is an alloy?

Answer 24

An alloys is a mixture of two or more elements, one of which must be a metal.

Question 25

~common exam question~ Why are alloys harder than pure metals?

Answer 25

In pure metals, the atoms are arranged in layers which can slip and slide. This means that it is soft. In an alloy, the layers are distorted and so the layers of atoms can’t slip or slide.

Question 26

Give three examples of shape memory alloys.

Answer 26

1) the thermostat in kettles 2) the wires on braces 3) frames on glasses

Question 27

Give the definition of a shape memory alloy.

Answer 27

A shape memory alloy is one that returns to it’s original shape after being deformed.

Question 28

What does HDPE and LDPE stand for?

Answer 28

High density polythene and low density polythene.

Question 29

What do the properties of polymers depend on?

Answer 29

The properties of polymers depend on the monomers used to make it and the conditions under which we choose to make it.

Question 30

What conditions are needed to form HDPE?

Answer 30

Using a catalyst at 50 degrees and a slightly raised pressure.

Question 31

What is the structure of HDPE?

Answer 31

HDPE is made up of straighter polythene molecules packed closely together to make it stronger. As a result it has a higher softening temperature.

Question 32

What conditions are needed to make LDPE?

Answer 32

You need a very high pressure and a trace of oxygen.

Question 33

What is the structure of LDPE?

Answer 33

The polymer chains are branched out and so can’t be closely packed together.

Question 34

What do thermosoftening polymers do?

Answer 34

They soften or melt when heated due to weak intermolecular forces between neighbouring polymer chains.

Question 35

What is the structure of thermosetting polymers?

Answer 35

Thermosetting polymers have a high melting point because of strong cross links between neighbouring chains.

Question 36

What is the structure of metals?

Answer 36

Metals are made up of ions arranged in a giant lattice. The ions are arranged in layers. The ions are surrounded by delocalised electrons. The positive ions and the delocalised electrons are attracted to each other.