2. Essential Chemistry for Biology

Question 1

matter

Answer 1

Anything that occupies space and has mass

Question 2

mass

Answer 2

A measure of the amount of material in an object.

Question 3

element

Answer 3

A substance that cannot be broken down into other substances by chemical reactions.

Question 4

periodic table of elements

Answer 4

A list of all the elements—the 92 that occur naturally and others that are human-made.

Question 5

trace elements

Answer 5

Less than 0.01% of your weight is made up of 14 trace elements, required in only very small amounts, but you cannot live without them.

Question 6

compounds

Answer 6

Substances that contain two or more different elements in a fixed ratio.

Question 7

atom

Answer 7

The smallest unit of matter that still retains the properties of an element.

Question 8

proton

Answer 8

A subatomic particle with a single negative charge (+)

Question 9

electron

Answer 9

A subatomic particle with a single negative charge (-)

Question 10

neutron

Answer 10

Is electrically neutral (has no charge).

Question 11

nucleus

Answer 11

Atom’s central core.

Question 12

atomic number

Answer 12

All atoms of a particular element have the same unique number of protons.

Question 13

mass number

Answer 13

The sum of the number of protons and neutrons.

Question 14

atomic mass

Answer 14

The sum of its protons and neutrons.

Question 15

isotopes

Answer 15

An element that have the same number of protons and behave identically in chemical reactions, but they have different numbers of neutrons.

Question 16

radioactive istope

Answer 16

An isotope which the nucleus decays spontaneously, shedding particles and energy (radiation).

Question 17

chemical bonds

Answer 17

Chemical reactions enable atoms to transfer or share electrons. These interactions usually result in atoms staying close together, held by attractions called chemical bonds.

Question 18

ions

Answer 18

Atoms (or molecules) that are electrically charged as a result of gaining or losing electrons.

Question 19

ionic bond

Answer 19

The attraction between oppositely charged ions

Question 20

covalent bond

Answer 20

Two atoms share one or more pairs of electrons.

Question 21

molecule

Answer 21

Group of atoms held together by covalent bonds.

Question 22

polar molecule

Answer 22

An uneven distribution of charge that creates two poles, one positive pole and one negative pole.

Question 23

hydrogen bonds

Answer 23

Weak electrical attractions between neighbouring water molecule caused by the polarity of water.

Question 24

chemical reactions

Answer 24

Changes in the chemical composition of matter. (reactants and products)

Question 25

cohesion

Answer 25

The tendency of molecules of the same kind to stick together.

Question 26

evaporative cooling

Answer 26

When a substance evaporates (changes from a liquid to a gas), the surface of the liquid that remains cools down.

Question 27

solution

Answer 27

A liquid consisting of a homogeneous mixture of two or more substances.

Question 28

solvent

Answer 28

The dissolving agent.

Question 29

solute

Answer 29

Substance that is dissolved.

Question 30

aqueous solution

Answer 30

A solution when water is solvent.

Question 31

acid

Answer 31

A chemical compound that releases H + to a solution.

Question 32

base

Answer 32

A compound that accepts H + ions and removes them from a solution.

Question 33

pH scale

Answer 33

A measure of the hydrogen ion H + concentration in a solution. The scale ranges from 0 (most acidic) to 14 (most basic). Each pH unit represents a tenfold change in the concentration of H +.

Question 34

buffers

Answer 34

Substances that minimize changes in pH by accepting H + when that ion is in excess and donating H + when it is depleted.

Question 35

half-life

Answer 35

The time it takes for 50% of a radioactive isotope to decay.