Unit 2: Chem Review, Water, and Biochem Pt I

Question 1

Define

Matter

Answer 1

Any substance that occupies space and has mass

Question 2

Define

Elements

Answer 2

A form of matter with specific chemical and physical properties

Question 3

How many elements are there?

Answer 3

98 naturally occurring

118 known / stable

Question 4

List

Most common elements in the body (6)

Answer 4

Carbon

Hydrogen

Oxygen

Nitrogen

Phosphorus*

Sulfur*

Question 5

List

Subatomic particles

Answer 5

Proton

Neutron

Electron

Question 6

Properties of

Protons

Answer 6

Positive

Mass = 1 amu

In nucleus

Question 7

Properties of

Neutrons

Answer 7

Neutral

Mass = 1 amu

In nucleus

Question 8

Properties of

Electrons

Answer 8

Negative

Negligible mass

Surrounding nucleus

Question 9

Adding or removing protons changes…

Answer 9

the element and the atomic number

Question 10

Adding or removing neutrons changes…

Answer 10

mass of an atom;

creates different isotopes (forms) of an element

Question 11

Adding or removing electrons changes…

Answer 11

the charge of the atom

Question 12

Define

Atomic mass

Answer 12

Average mass of one mole of an element, which takes isotopes (which have different mass numbers) into account

FYI: You will NOT need to memorize atomic mass v. mass number

Question 13

Define

Isotope

Answer 13

Different forms of an element with the same number of protons but different numbers of neutrons

Question 14

Define

Electron orbital

Answer 14

“Shells” around a nucleus where electrons are likely to be found

2 in first

8 in second and third

Question 15

Define

Valence shell

Answer 15

Outermost electron orbital in an atom

Question 16

Define

Molecule

Answer 16

Chemical joining of two or more atoms

Question 17

Define

Covalent bond

Answer 17

Sharing of electrons between atomic nuclei

Question 18

Define

Polar covalent

Answer 18

A covalent bond where electrons are more likely to be found around one atom (which is more electronegative)

Question 19

Define

Nonpolar covalent

Answer 19

A covalent bond where electrons are equally shared

Question 20

What leads to the formation of an cation?

Answer 20

Cation (cat-eye-on) = positive ion

Occurs when an atom loses electrons

Most common in first two groups (columns) of periodic table

Question 21

What leads to the formation of an anion?

Answer 21

Anion = Negative ion

Occurs when atoms take electrons to become stable

Question 22

Why is water polar

Answer 22

Oxygen is electronegative, leading to the formation of polar covalent bonds between oxygen and two hydrogens. The bent shape means more electrons (negative) are at the oxygen end

Question 23

Define

Polarity

Answer 23

Unequal distribution of charge in a molecule

Question 24

Define

Polar molecules

Answer 24

Molecules with partial positive and negative regions Ex: Water

Question 25

*Define* **Nonpolar molecules**

Answer 25

Molecules with no partial positive and negative regions Ex: Hydrocarbons

Question 26

*Define* **Hydrophobic**

Answer 26

"Water fearing" Nonpolar; avoids water

Question 27

*Define* **Hydrophilic**

Answer 27

"Water loving" Polar; dissolves in or attracts to water

Question 28

**Density of water**

Answer 28

Liquid: Most dense due to hydrogen bonds pulling molecules closer together than in solid form Solid: Less dense than liquid

Question 29

**Importance of water's density as a solid**

Answer 29

Ice floats - Good for insulating bodies of water - Prevents freezing / sinking of ice in bodies of water so that Earth is not a giant icecube

Question 30

*Define* **Specific heat capacity**

Answer 30

Energy needed to increase the temperature of a substance

Question 31

**Water's specific heat capacity**

Answer 31

Very high, which helps regulate temperature within organisms and near large bodies of water

Question 32

*Define* **Heat of vaporization**

Answer 32

Energy required to convert substance from liquid to gas

Question 33

**Water's heat of vaporization**

Answer 33

Very high, leading to evaporative cooling

Question 34

*Define* **Solvent**

Answer 34

A substance that dissolves other substances

Question 35

*Define* **Solute**

Answer 35

A substance that dissolves in another substance

Question 36

*Define* **Universal solvent**

Answer 36

Water can cause dissociation of all polar molecules

Question 37

*Define* **Cohesion**

Answer 37

Attraction of like molecules (ex: water attracted to water)

Question 38

*Define* **Adhesion**

Answer 38

Attraction of different molecules (ex: water attracted to glass)

Question 39

*Define* **Surface tension**

Answer 39

Water's cohesion pulls molecules together with enough force to overcome droplets being flattened by gravity; some objects remain on the top of water

Question 40

*Define* **pH**

Answer 40

Measure of acidity or alkalinity (basicity)

Question 41

*Define* **Acid**

Answer 41

A substance that increases [H+] in solution pH \< 7

Question 42

*Define* **Base**

Answer 42

A substance that increases [OH-] and/or decreases [H+] in solution pH \> 7

Question 43

*Describe the* **pH scale**

Answer 43

14 - strongest base \>7 - base 7 - neutral \<7 - acid 1 - strongest acid\*

Question 44

*Define* **Buffer**

Answer 44

A substance that prevents rapid change of pH in a solution