Topic 3 Material Worlds

Question 1

What is the atomic number?

Answer 1

The atomic number refers to the number of protons in the nucleus of an atom (and electrons).

Question 2

What is the atomic mass?

Answer 2

The atomic mass refers to the total number of protons and neutrons in the nucleus of an atom.

Calculated by the sum of the percentage abundance of on isotope in decimal form multiplied by the atomic mass.

For carbon: ( 12 x 0.99 ) + ( 13 x 0.01 ) = 12.01 ( not accurate )

Question 3

What is an isotope?

Answer 3

An isotope of an element has different numbers of neutrons and are found naturally in varying abundances i.e. Carbon 12 and Carbon 13.

Question 4

What is an isotope?

Answer 4

An isotope of an element has different numbers of neutrons and are found naturally in varying abundances i.e. Carbon 12 and Carbon 13.

Question 5

What happens to the energy of shells as you move further from the nucleus?

Answer 5

As you get further from the nucleus of an atom each shell increases in energy.

Question 6

What is a group in the periodic table?

Answer 6

A set of chemicals commonly placed in a vertical column in the periodic table, having related chemical properties.

Question 7

What is a orbital?

Answer 7

An orbital is a volume of space where an electron is expected to be found. Orbitals have different shapes and energy levels associated with them.

The 4 types of orbital are: S, P, D and F ordered by increasing energy levels. Each orbital can hold 2 electrons.

Question 8

What shape is an S orbital?

Answer 8

An S orbital is circular and the lowest energy level.

Question 9

What shape is a P orbital?

Answer 9

A P orbital has a dumbbell shape (figure of 8) and is of a higher energy than an S orbital. There are 3 P orbitals on each shell after the first.

Question 10

How to write election configurations

Answer 10

Carbon

Complex: 1s^2, 2s^2, 2p^2

Simple: 2, 4

Question 11

What is electron configuration?

Answer 11

This is the arrangement of electrons in shells within an atom.

Question 12

What is electron configuration?

Answer 12

This is the arrangement of electrons in shells within an atom.

Question 13

What are some physical properties of metals?

Answer 13

• Are shiny
• good conductors of heat
• good conductors of electricity
• easily drawn out into wire (ductile)
• easily hammered into a shape (malleable)

Question 14

What is metallic bonding?

Answer 14

Metallic bonding is when a lattice of positive metal ions are held together by a sea of delocalised free electrons.

Question 15

What causes metals to be weaker?

Answer 15

When there are voids and gaps in the structure, the structure can become distorted and become weaker.

Question 16

Why do ionic solids have high melting temperatures?

Answer 16

a lot of energy is required to overcome the electrostatic forces holding the ions together.

Question 17

What is ionic bonding?

Answer 17

Ionic bonding occurs when elections are donated from a metal atom to form a positive metal ion, and the elections are received by a non metal to form a negative ion. These two opposite ions are attracted to each other via electrostatic forces.

Ionic bonding generally occurs between group 1,2 and group 16,17 as atoms can loose or gain 2 electrons.

Question 18

Can ionic compounds conduct electricity?

Answer 18

When ionic compounds are in a solid state they cannot conduct electricity as there is no free ions or electrons to move.

When in a liquid state they con conduct electricity as the ions are free to move.

Ionic compounds also dissolved in liquid will conduct electricity.

Question 19

What is a covalent bond?

Answer 19

A type of chemical bond where a pair of electrons is shared between two atoms.

Question 20

What is a diatomic molecule?

Answer 20

This is a molecule that consists of 2 atoms.

Question 21

What is a giant covalent structure?

Answer 21

A lattice of very many atoms, each covalently bonded to other atoms.

Question 22

How does graphite differ from diamond?

Answer 22

In diamond each carbon is covalently bonded to 4 other carbon atoms forming a strong, stable giant covalent structure.

In graphite each carbon is covalently bonded to 3 other carbon atoms. This creates layers of Carbon sheets that can easily slide over eachother. As each carbon only has 3 bonds 4th election election becomes delocalised and can travel through the structure, allowing it to conduct electricity.

Question 23

What are hydrocarbons?

Answer 23

These ave molecules containing only hydrogen and carbon atoms.

Question 24

What is a monomer and a polymer?

Answer 24

A monomer is a small covalent molecule that can he considered a single unit i.e. Ethene

A polymer is a long chain of repeating units (monomers) i.e. Polyethene.