Ionic and Covalent Bonding

Question 1

When are ions formed?

Answer 1

When electrons are transferred from one atom to another. The simplest ions are single atoms which have either lost or gained 1, 2 or 3 electrons so they’ve got a full outer shell.

Question 2

What ions do group 1 elements form?

Answer 2

1+

Question 3

What ions do group 2 elements form?

Answer 3

2+

Question 4

What ions do group 6 elements form?

Answer 4

2-

Question 5

What ions do group 7 elements form?

Answer 5

1-

Question 6

What are the compound ions I need to know?

Answer 6

Nitrate…NO3-
Carbonate…CO3 2-
Sulfate…SO4 2-
Ammonium…NH4+

Question 7

What does an electrostatic attraction do?

Answer 7

It holds positive and negative ions together- its very strong.
When atoms are held together like this, its called ionic bonding.

Question 8

What is an ionic bond?

Answer 8

An electrostatic attraction between two oppositely charged ions.

Question 9

What do you get when oppositely charged ions form an ionic bond?

Answer 9

An ionic compound.

Question 10

What are ionic crystals?

Answer 10

Giant lattices of ions.

Question 11

What is a giant lattice?

Answer 11

A lattice is just a regular structure. The structure’s called giat because it’s made up of the same basic unit repeated over and over again.

Question 12

What three physical properties can the structure of ionic compounds determine?

Answer 12

Electrical conductivity
Melting and boiling points
Solubility

Question 13

What features of an ionic compound determines electrical conductivity?

Answer 13

Ionic compounds conduct electricity when they’re molten or dissolved- not when they’re solid.
The ions in a liquid are free to move (and they carry charge).
In a solid they’re fixed in position by the strong ionic bonds.

Question 14

What features of an ionic compound determines melting and boiling points?

Answer 14

Ionic compounds have high melting and boiling points.
The giant ionic lattices are held together by strong electrostatic forces.
It takes loads of energy to overcome these forces, so melting and boiling points are very high.

Question 15

What features of an ionic compound determines solubility?

Answer 15

Ionic compounds tend to dissolves in water.
Water molecules are polar- part of the molecule has a small negative charge, and the other bits have small positive charges.
The water molecules pull the ions away from the lattice and cause it to dissolve.

Question 16

What are the smallest parts of compounds that can take part in chemical reactions?

Answer 16

Molecules.

Question 17

How are molecules formed?

Answer 17

When two or more atoms bond together.

Question 18

How are molecules held together?

Answer 18

By strong covalent bonds.

Question 19

What is a covalent bond?

Answer 19

A shared pair of electrons.

Question 20

What happens in dative covalent bonds?

Answer 20

One of the atoms provides both of the shared electrons.

Question 21

Why are simple covalent compounds mainly gases?

Answer 21

They have strong bonds within molecules by weak forces between the molecules.

Question 22

Explain the behaviour of electrical conductivity in simple covalent compounds.

Answer 22

Simple covalent compounds don’t conduct electricity because there are no free ions or electrons to carry the charge.

Question 23

Explain the behaviour of melting and boiling points in simple covalent compounds.

Answer 23

Simple covalent compounds have low melting and boiling points because the weak forces between molecules are easily overcome.

Question 24

Explain the behaviour of solubility in simple covalent compounds.

Answer 24

Simple covalent compounds dissolve in water depending on how polarised the molecules are.

Question 25

What are the two types of giant covalent carbon structures I need to know about?

Answer 25

Graphite and diamond.

Question 26

What are giant covalent structures?

Answer 26

Giant covalent structures have a huge network of covalently bonded atoms. Their atoms are arranged into giant lattices, which are strong structures because of the many bonds involved.

Question 27

Why can carbon atoms form a macromolecular/giant covalent structure?

Answer 27

They can form four strong, covalent bonds.

Question 28

What is the structure of graphite like?

Answer 28

The carbon atoms are arranged in sheets of flat hexagons covalently bonded with three bonds each. The fourth outer electron of each carbon atom is delocalised. The sheets of hexagons are bonded together by weak van der Waals forces.

Question 29

Graphites structure means it has certain properties. What are these?

Answer 29

The weak bonds between layers-easily broken so sheets can slide over each other- graphite feels slippery. The delocalised electrons are free to move along the sheets- current can flow. The layers are quite far apart compared to the length of the covalent bonds- so low density and used to make strong, lightweight sports equipment. Because of the strong covalent bonds in the hexagon sheets- very high melting point. Insoluble in any solvent- covalent bonds in sheets are too difficult to break.

Question 30

What is the structure of diamond like?

Answer 30

It is made up of carbon atoms. Each carbon atom is bonded to four other carbon atoms. The atoms arrange themselves in a tetrahedral shape- its crystal lattice structure.

Question 31

What properties of diamond are because of its strong covalent bonds?

Answer 31

Very high melting point. Extremely hard. Vibrations travel easily through the stiff lattice- good thermal conductor. It can't conduct electricity- all other electrons are held in localised bonds. Like graphite, won't dissolve in solvent.

Question 32

What is meant by the term ionic bonding?

Answer 32

Positive and negative ions attract one another and bind together forming a new substance, usually a metal and a non-metal through loosing or gaining an electron. The metal looses one or more electrons and the non-metal gains one or more electrons.

Question 33

Why does ammonium chloride conduct electricity when dissolved in water and not when it is solid?

Answer 33

In the solid state, it does not have the free ions flowing needed to conduct electricity. The atoms are locked in place. However in the liquid state, it does have free ions. The free ions allow the conductivity of electricity.

Question 34

True or false, potassium fluoride exists as a molecule? Why?

Answer 34

Potassium fluoride exists as a lattice consisting of potassium and fluoride ions.