Bonding, structure and properties of matter

Question 1

What are ions?

Answer 1

Ions are charged particles formed when atoms, or groups of atoms, lose or gain electrons to obtain full outer shells.

Question 2

When do ions form?

Answer 2

Ions form when a metal reacts with a non-metal.

Question 3

What are ionic bonds?

Answer 3

Ionic bonds are formed between a metal and non-metal.
An atom of the metal will lose an electron and form a positive ion. An atom of the non-metal will gain an electron and form a negative ion.
The ionic bond is the electrostatic force of attraction between a positively charged metal ion and a negatively charged non-metal ion.

Question 4

Why do metals form positive ions?

Answer 4

Because they lose a (negative) electron so therefore makes it more positive.

Question 5

Describe how ions produced by elements in some groups have the electronic structure of a noble gas.

Answer 5

Because they gain/lose electrons to form a full outer shell and noble gases have full outer shells.

Question 6

How does the charge of an ion relate to its group number.

Answer 6

For elements in groups 1, 2 and 3, the number of electrons lost is the same as the group number.

Question 7

Describe the structure of ionic compounds.

Answer 7

Ionic compounds have regular structures, called giant ionic lattices. In a giant ionic lattice, there are strong electrostatic forces of attraction acting in all directions between the oppositely charged ions.

Question 8

What are the limitations of using dot and cross diagram for ionic compounds?

Answer 8

Fails to illustrate the 3D arrangements of the atoms and electron shells.

Question 9

What is a covalent bond?

Answer 9

A covalent bond forms when two non-metal atoms share a pair of electrons.

Question 10

How do covalent bonds and molecules relate?

Answer 10

The atoms in a molecule are always joined together by a covalent bond.

Question 11

Covalent bonds can come in two forms, what are they?

Answer 11

Small molecules, which contain a fixed number of atoms joined by covalent bonds.
Giant covalent substances, which contain many atoms joined by covalent bonds.

Question 12

What is the molecular formula (covalent bonds).

Answer 12

A molecular formula shows the actual numbers of atoms of each element in a molecule. For example, the formula for methane is CH4.

Question 13

What is metallic bonding?

Answer 13

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 14

Why are metals conductors?

Answer 14

Metals conduct electricity by allowing free electrons to move between the atoms (delocalised electrons).

Question 15

What is the metallic bond holding together?

Answer 15

The metallic bond is the force of attraction between these free-moving (delocalised) electrons and positive metal ions.

Question 16

What are the three states of matter?

Answer 16

Liquid, solid and gas.

Question 17

Explain changes of state using particle theory.

Answer 17

Increased kinetic energy causes the the bonds that hold particles in place to be broken and begin moving freely.

Question 18

(aq)

Answer 18

Aqueous (dissolved in water).

Question 19

Explain how the structure of giant covalent structures affects their properties.

Answer 19

They have very high melting points and boiling points . This is because large amounts of energy are needed to overcome their strong covalent bonds to make them melt or boil.

Question 20

Explain how the structure of metals and alloys affects their properties

Answer 20

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.

Question 21

What is an alloy?

Answer 21

An alloy is a mixture of two or more elements, where at least one element is a metal.

Question 22

Explain why alloys are harder than pure metals.

Answer 22

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. 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 23

Explain why alloys are harder than pure metals (simple).

Answer 23

Pure metals - atoms in layers so easy to slide over.

Alloys - atoms all different sizes so harder to slide over so is therefore stronger/harder.

Question 24

Describe the differences between diamond and graphite structure/bonding.

Answer 24

Diamond -
Each carbon atom joined by 4 others
No free electrons
Hard/strong because held together by strong covalent bonds
Graphite -
Each carbon atom joined by 3 others
Delocalised electrons
Conducts electricity
Layers slide over each other because forces in between are weak

Question 25

What are fullerenes?

Answer 25

Fullerenes are molecules of carbon atoms with hollow shapes. Buckminsterfullerene was the first fullerene to be discovered.

Question 26

What is a nanotube?

Answer 26

A nanotube is like a layer of graphene, rolled into a cylinder.