Matter organisation and chemical reactions

Question 1

What is the distinction between an atom and an element?

Answer 1

Elements are made up of their atoms, which will all have the same number of protons in their nucleus
E.g. carbon is made up of atoms which have 6 protons in their nucleus

Question 2

The amount of which subatomic particle in an atom is consistent between different ions and isotopes?

Answer 2

The number of protons

This dictates an atom/element’s atomic number

Question 3

The amount of which two subatomic particles is the same in an atom?

Answer 3

The protons and electrons, therefore atoms are electrically neutral

Question 4

What is an ion?

Answer 4

An atom which has lost or gained one or more of it’s electrons and therefore has a positive or negative charge

Question 5

The amount of which subatomic particle differs between isotopes?

Answer 5

Neutrons

Question 6

The sum of which two subatomic particles equals an atoms mass number?

Answer 6

Protons and neutrons

Question 7

How many electrons can be held in the following electron shells?
1. First shell
2. Second shell
3. Third shell

Answer 7

1. 2
2. 8
3. 18

Question 8

What is a molecule?

Answer 8

Two or more atoms sharing electrons

Question 9

What is a compound?

Answer 9

A substance containing two or more different atoms

All compounds are molecules but not all molecules are compounds e.g. O₂

Question 10

What is a free radical?

Answer 10

An atom or molecule with an unpaired electron/odd number of electrons in it’s outermost (valence) shell

Question 11

How does a radical differ from an ion?

Answer 11

1. All ions are charged whereas radicals can be neutral or charged
2. Radicals are unstable and highly reactive

Question 12

Why are radicals harmful to the body?

Answer 12

They are highly reactive and therefore will break apart important body molecules to lose or gain an electron to become stable

Question 13

Name some sources of free radicals

Answer 13

1. UV radiation in sunlight
2. X-rays
3. Ozone
4. Cigarette smoke
5. Air pollutants

Question 14

Name some conditions linked to free radicals

Answer 14

1. Cancer
2. Atherosclerosis
3. Alzheimer’s disease
4. Emphysema
5. Diabetes
6. Cataracts
7. Macular degeneration
8. Rheumatoid arthritis

Question 15

Name some dietary antioxidants

Answer 15

1. Selenium
2. Zinc
3. Beta-carotene
4. Vitamin C
5. Vitamin E

Question 16

What types of foods are typically high in antioxidants?

Answer 16

Red, blue or purple fruits and vegetables

Question 17

List the four key features of organic compounds

Answer 17

1. Always contain carbon
2. Usually contain hydrogen
3. Always have covalent bonds
4. Most are large molecules

Question 18

List the three key features of inorganic compounds

Answer 18

1. Usually lack carbon (exceptions include CO₂, HCO₃ and H₂CO₃)
2. Are structurally simple, their molecules have only a few atoms e.g. water, salts, acids and bases.
3. They can have ionic or covalent bonds.

Question 19

What type of reactions in the body does anabolism refer to?

Answer 19

Synthesis reactions - when atoms, ions or molecules combine to form new and larger molecules

Question 20

Are anabolic reactions usually exergonic or endergonic?

Answer 20

Endergonic - they absorb more energy than they release

Question 21

What type of reactions in the body does catabolism refer to?

Answer 21

Decomposition reactions - the splitting up of larger molecules in to smaller molecules, ions or atoms

Question 22

Are catabolic reactions usually exergonic or endergonic?

Answer 22

Exergonic - they release more energy than they absorb

Question 23

Besides synthesis and decomposition reactions, what are the other three types of reaction in the body?

Answer 23

1. Exchange - a combination of synthesis and decomposition (ions are exchanged)
2. Reversible - can occur in either direction under the right conditions
3. Oxidation-reduction - used to break down food molecules to produce energy

Question 24

What are monomers and polymers?

Answer 24

Monomers are molecules that can be bonded to other identical molecules to form a polymer

Question 25

What are isomers?

Answer 25

Molecules that have the same molecular formula (amount of each atom present) but different structures