C2: Biological Molecules Part I

Question 1

When carbon dioxide dissolves in water, what does it form after reaction?

Answer 1

an acid

Question 2

What is a compound?

Answer 2

a substance that has two or more elements in a fixed ratio

Question 3

What are the 4 most common elements in our body? (In order)

Answer 3

oxygen, carbon, hydrogen, nitrogen

Question 4

What are trace elements common additives to?

Answer 4

food and water

Question 5

Define an atom.

Answer 5

the smallest unit of matter that still has the properties of an element

Question 6

What is an atom’s atomic number?

Answer 6

the unique number of protons

Question 7

How do you calculate an atom’s atomic mass?

Answer 7

mass of protons + mass of neutrons

Question 8

What is an atom’s mass number?

Answer 8

sum of the number of its protons and neutrons

Question 9

Differentiate mass number and atomic mass.

Answer 9

Mass number is the number of protons and neutrons on atom has. Atomic mass is the combined mass of the protons and neutrons. They are approximately equal to each other.

Question 10

What are the outermost electron shells called?

Answer 10

valence shells

Question 11

What is a valence number?

Answer 11

the number of electrons in the outer shell

Question 12

What are isotopes?

Answer 12

different forms of an element; same number of protons but different number of neutrons

Question 13

What is an ionic bond?

Answer 13

a chemical bond formed by the transferring of electrons between atoms (oppositely charged ions then attract)

Question 14

What is a covalent bond?

Answer 14

a chemical bond formed when two atoms share electrons

Question 15

What is the difference between a non-polar covalent bond and a polar covalent bond?

Answer 15

In non-polar covalent bonds, electrons are shared equally. In polar covalent bonds, electrons are pulled closer to a certain atom.

Question 16

What is electronegativity?

Answer 16

measure of an atom’s ability to attract electrons towards itself in a chemical bond

Question 17

What is an ion?

Answer 17

an atom or molecule with an electric charge due to the gain or loss of electrons

Question 18

What are hydrogen bonds?

Answer 18

weak bonds that form between polar molecules

Question 19

What are partial charges?

Answer 19

charges that result from uneven electron distribution in polar covalent bonds

Question 20

Define reactants and products.

Answer 20

Reactants are the starting materials in a chemical reaction and products are the resulting materials.

Question 21

What is cohesion and adhesion?

Answer 21

Cohesion is the attraction between same molecules. Adhesion is the attraction between different molecules.

Question 22

What is surface tension?

Answer 22

a measure of how difficult it is to break the surface of a liquid

Question 23

Why is ice less dense than liquid water?

Answer 23

The arrangement of molecules in ice causes the molecules to be spaced far apart

Question 24

What are solutions, solvents, and solutes?

Answer 24

Solutions are mixtures composed of two or more substances. Solvents are substances that allow other substances to be dissolved in. Solutes are the substances that get dissolved.

Question 25

Why are non-polar molecules insoluble in water?

Answer 25

The water molecules are attracted to each other instead of the non-polar molecules.

Question 26

What is the specific heat of a substance?

Answer 26

the amount of heat required to raise the substance’s temperature by a given amount

Question 27

What is the specific heat of water?

Answer 27

1 calorie

Question 28

What is thermal energy?

Answer 28

energy associated with the random movement of atoms and molecules

Question 29

Describe the process of evaporative cooling.

Answer 29

When a substance evaporates, the surface of the remaining liquid cools down.

Question 30

What is the latent heat of vaporization?

Answer 30

the measure of the heat energy needed to turn a liquid into gas

Question 31

What is a reagent?

Answer 31

substance that is used to measure or produce other substances

Question 32

What is the pH scale?

Answer 32

scale that measures acidity or basicity of a solution (a higher concentration of H+ ions results in higher acidity)

Question 33

Define acids and bases.

Answer 33

Acids are substances that release H+ ions when dissolved in water. Bases are substances that accept H+ ions.

Question 34

What minimizes changes in pH?

Answer 34

a buffer