Lecture 2 - Essential Chemistry for Biology

Question 1

What is Matter?

Answer 1

anything that occupies space and mass

Question 2

Element?

Answer 2

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

Question 3

How many naturally occurring elements on Earth?

Answer 3

92

Question 4

How many elements are essential to the human body?

Answer 4

25

Question 5

Oxygen, carbon, hydrogen, and nitrogen make up what percentage of the body?

Answer 5

96%

Question 6

What are Trace Elements?

Answer 6

• elements that are required in only very small amounts

- Essential for life

Question 7

Atom

Answer 7

Smallest unit of matter that still retains the property of an element.

Question 8

Protons

Answer 8

Positive charge in the nucleus.

Question 9

Neutrons

Answer 9

(no charge): in the nucleus

Question 10

Electrons

Answer 10

(negative charge): orbit the nucleus

Question 11

Atomic number

Answer 11

Number of protons determine what element it is

Question 12

Mass

Answer 12

measure of amount of material in an object

Question 13

Mass number

Answer 13

is the sum of the number of protons and neutrons in its nucleus.

Question 14

Isotopes

Answer 14

• alternate mass forms of an element
• same number of protons
• same number of electrons
• But different number of neutrons

Question 15

compounds

Answer 15

substances that contain two or more elements in a fixed ratio

Question 16

What determines the the element of an atom?

Answer 16

Protons

Question 17

Charged atoms are called what?

Answer 17

Ion

Question 18

How are ionic bonds formed?

Answer 18

formed between oppositely charged ions

Question 19

What happens in Ionic bonds?

Answer 19

a transfer of electrons bonds atoms together

Question 20

When does a covalent bond form?

Answer 20

forms when two atoms share one or more pairs of

outer-shell electrons.

Question 21

out of all the various bonds, which are the strongest?

Answer 21

Covalent bonds

Question 22

what is a Molecule?

Answer 22

two or more atoms held together by covalent bonds

Question 23

Polar molecule?

Answer 23

• an uneven distribution of charge

- Electrons in its covalent bonds are not shared equally

Question 24

Is water Polar?

Answer 24

Yes

Question 25

What are weak attractions called?

Answer 25

Hydrogen bonds

Question 26

The polarity of water results in _______?

Answer 26

weak electrical attractions between neighboring water molecules.

Question 27

How do cells constantly rearrange molecules?

Answer 27

by breaking existing chemical bonds and forming new ones

Question 28

Chemical reaction?

Answer 28

changes in the chemical composition of matter

Question 29

reactants?

Answer 29

starting materials

Question 30

products

Answer 30

end materials

Question 31

cells are composed of what % of water

Answer 31

70-95%

Question 32

What are the properties of water?

Answer 32

1. )water’s cohesive nature
2. )water’s ability to moderate temperature
3. ) Ice Floats
4. )the Solvent of life

Question 33

Cohesion?

Answer 33

tendency of molecules of the same kind to stick together

Question 34

surface tension

Answer 34

measure of how difficult it is stretch or break the surface of a liquid

Question 35

Hydrogen bonds give water an usually ___ surface tension

Answer 35

High

Question 36

Heat?

Answer 36

amount of energy
associated with the movement
of the atoms and molecules in
a body of matter.

Question 37

Temperature?

Answer 37

measures the
intensity of heat (the average
speed of the molecules).

Question 38

Why does ice float?

Answer 38

it is less dense than liquid water

Question 39

Evaporating cooling occurs when?

Answer 39

a substance evaporates and the surface of the liquid remaining behinds cools down.

Question 40

Solution?

Answer 40

liquid consisting of a homogenous mixture of two or more substances.

Question 41

Solvent

Answer 41

dissolving agent

Question 42

solute

Answer 42

dissolved agent

Question 43

Aqueous solution?

Answer 43

When water is the solvent, the result is an aqueous solution

Question 44

Acid?

Answer 44

a chemical compound that releases H+ ions when placed in water

Question 45

Base?

Answer 45

a compound that accepts H+ ions (removes them from the solution) when placed in water.

Question 46

pH scale?

Answer 46

describes the acidity of a solution

Question 47

The reactive properties (chemical behavior) of an atom

mostly depend on the number of

Answer 47

electrons in the outer electron shell of the atom.

Question 48

Water molecules form hydrogen bonds because

Answer 48

the water molecule

is polar.