Chapter 2:Chemistry

Question 1

What is an element?

Answer 1

A substance made of atoms that share the SAME number of protons and cannot be broken down into simpler substances by chemical methods.

Question 2

How many elements are in the periodic table?

Answer 2

118 elements.

Question 3

Define a compound.

Answer 3

Two or more elements chemically bonded together in a fixed proportion.

Question 4

Give an example of a compound.

Answer 4

• Carbon Dioxide
• Sodium Chloride

Question 5

What is a mixture?

Answer 5

Two or more elements not chemically bonded together.

Question 6

Provide examples of mixtures.

Answer 6

• Sand and Water
• Oil and Water

Question 7

What are atoms?

Answer 7

Tiny particles that are the building blocks of all matter.

Question 8

Describe the structure of an atom.

Answer 8

A central nucleus containing neutrons and protons surrounded by electrons in shells.

Question 9

What is the relative mass and charge of a proton?

Answer 9

Relative Mass: 1, Relative Charge: +1

Question 10

What is the relative mass and charge of a neutron?

Answer 10

Relative Mass: 1, Relative Charge: 0

Question 11

What is the relative mass and charge of an electron?

Answer 11

Relative Mass: 0, Relative Charge: -1

Question 12

What is the overall charge of an atom?

Answer 12

Neutral, because electrons and protons have equal and opposing charges.

Question 13

What is the purpose of neutrons in the nucleus?

Answer 13

To hold the nucleus together.

Question 14

What is the Proton Number (Atomic Number)?

Answer 14

The number of protons in the nucleus of an atom, denoted by the letter ‘Z’.

Question 15

What does the Nucleon Number (Mass Number) represent?

Answer 15

The total number of protons and neutrons in the nucleus of an atom.

Question 16

How is the mass number calculated?

Answer 16

Mass number = number of protons + number of neutrons.

Question 17

What is the general electronic configuration format for elements?

Answer 17

(2.8.8)

Question 18

What are isotopes?

Answer 18

Different atoms of the same element with the same number of protons but different numbers of neutrons.

Question 19

Do isotopes have the same chemical properties?

Answer 19

Yes, because they have the same number of outer shell electrons.

Question 20

What affects the physical properties of isotopes?

Answer 20

The difference in mass.

Question 21

What is the formula for calculating relative atomic mass?

Answer 21

Relative atomic mass = ( % of isotope 1 × mass number of isotope 1 + % of isotope 2 × mass number of isotope 2 ) / 100

Question 22

What is metallic bonding?

Answer 22

The electrostatic attraction between the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons.

Question 23

List properties of metallic bonding.

Answer 23

• Good electrical conductivity
• High melting and boiling points
• Malleability
• Ductility

Question 24

What are giant covalent structures?

Answer 24

Solids with very high melting points, where all the atoms are made of pure carbon.

Question 25

What are the properties of graphite?

Answer 25

* High melting and boiling points * Conducts electricity * Soft structure * Opaque/black

Question 26

What is a covalent bond?

Answer 26

Pairs of electrons shared between two atoms leading to noble gas electronic configuration.

Question 27

What types of covalent bonds exist?

Answer 27

* Single Bonds * Double Bonds * Triple Bonds

Question 28

What are the properties of covalent compounds?

Answer 28

* Weak intermolecular forces * Low melting and boiling points * Poor electrical conductivity

Question 29

Define cations and anions.

Answer 29

* Cations: Positive ions * Anions: Negative ions

Question 30

What are ionic bonds?

Answer 30

Strong electrostatic attraction between oppositely charged ions.

Question 31

What are typical properties of ionic compounds?

Answer 31

* High boiling and melting points * Good electrical conductivity when molten or aqueous * Brittle * Low volatility

Question 32

What is the structure of typical ionic compounds?

Answer 32

Giant lattice structures with a regular arrangement of alternating positive and negative ions.

Question 33

What is an atom?

Answer 33

An atom is the smallest particle that can exist. Everything is made from atoms. Atoms are shown in diagrams as small circles.

Question 34

What is an element?

Answer 34

An element is made up of one type of atom only. For example, a piece of pure copper is made up of only copper atoms.

Question 35

What is a compound?

Answer 35

A compound is a substance made up of two or more atoms of different elements chemically joined (or bonded) together. For example, carbon dioxide gas (CO2) consists of one carbon atom and two oxygen atoms bonded together.

Question 36

What is a molecule?

Answer 36

A molecule describes two or more atoms bonded together. All compounds are molecules and some elements are too.

Question 37

How do atoms of the same element appear in diagrams?

Answer 37

Atoms of the same element in diagrams will be drawn as the same size and they will be the same colour.

Question 38

How do atoms of different elements appear in diagrams?

Answer 38

If the atoms are of different elements, they will be a different colour or size.

Question 39

What is the symbol for nitrogen?

Answer 39

The symbol for nitrogen is N.

Question 40

What is the formula for sodium chloride?

Answer 40

The formula for sodium chloride is NaCl.

Question 41

What does the formula K2O represent?

Answer 41

The formula K2O consists of two potassium atoms (symbol K) and one oxygen atom (symbol O).

Question 42

Why is it important to write element symbols correctly?

Answer 42

Writing element symbols correctly is crucial because CO is the formula for carbon monoxide, while Co is the symbol for cobalt.