Week 2 - Chemical Foundations Of Life

Question 1

Atomic number

Answer 1

Number of protons in an atoms nucleus

Question 2

Mass number

Answer 2

Number of protons AND neutrons in the nucleus (mass number minus atomic number equals number of neutrons)

Question 3

Matter

Answer 3

Has mass and takes up space

Question 4

Element

Answer 4

unique matter form; cannot be broken down further by normal chem rxns

Question 5

Valence she’ll

Answer 5

Outermost electron layer of an atom

Question 6

Octet rule

Answer 6

Most shells want to hold eight electrons (most stable this way) - responsible for chemical bonds

Question 7

Hydrogen

Answer 7

1 proton
1 electron
1 valence electrons
1 bond it wants to form

Question 8

Carbon (C)

Answer 8

6 protons
6 electrons
4 valence electrons
4 bonds it wants to form

Question 9

Oxygen (O)

Answer 9

8 protons
8 electrons (6 valence)
6 bonds it wants to form

Question 10

Nitrogen (N)

Answer 10

7 protons
7 electrons (5 valence)
3 bonds it wants to form

Question 11

Ions

Answer 11

Atoms that have gained or lost electrons

Question 12

Cation

Answer 12

Positively charged atom (lost electrons)

Question 13

Anion

Answer 13

Negatively charged atom (gained electrons)

Question 14

Chemical bonds - 3 types

Answer 14

Covalent
Ionic
Hydrogen

Question 15

Covalent bond

Answer 15

Atoms SHARE valence electrons

Single covalent - each atom contributes one electron
Double covalent - each atom contributes two electrons

Question 16

Electronegativity

Answer 16

How strongly am atom pulls electrons towards it. Oxygen is very electronegative.

Depends on how many protons the atom has AND how far from those protons the valence electrons are (it’s a balance - more electron shells “shield” the outer electrons from being pulled more)

Question 17

Polar covalent bond

Answer 17

Bond has a partial charge due to electronegativity of one of the atoms involved

Question 18

Hydrogen bonds

Answer 18

Form between molecules; partial charge between the atoms due to polar covalent bonds within the molecules themselves.

Hydrogen bonds form between water molecules because oxygen-hydrogen bond is polar covalent due to oxygens greater electronegativity

Question 19

Chemical reactions

Answer 19

The making and breaking of chemical bonds

REACTANTS go in, PRODUCTS come out

Question 20

Cohesion (water)

Answer 20

Water molecules stick to each other (H bonds)

Question 21

Adhesion

Answer 21

Water molecules stick to OTHER molecules (those that have polar covalent bonds)

Question 22

Surface tension

Answer 22

Liquids ability to resist force at the interface of liquid and air for example, or another substance interface

Question 23

Specific heat

Answer 23

amt of energy needed to raise 1g of water by 1 deg C

Waters is very HIGH - absorbs heat slowly and releases it slowly

Question 24

Heat of vaporization

Answer 24

Amt of heat energy needed to turn 1g water into 1g water vapor (gas)

Question 25

Hydrophilic

Answer 25

Something that dissolves easily in water (loves water - like dissolves like) Water is polar and thus dissolves other polar substances

Question 26

Hydrophobic

Answer 26

Feat water; don’t dissolve in water (no polar substances like oil and fat)

Question 27

pH scale

Answer 27

A scale of acidity vs. alkalinity of a solution (acids are < 7.0, bases are >7.0); measures concentration of hydrogen ions (H+)

Question 28

Base

Answer 28

a solution that reduces H+ concentration (“proton receiver”) e.g. sodium hydroxide

Question 29

Acid

Answer 29

something that increases H+ concentration (“proton donor”) e.g. hydrochloric acid

Question 30

Important properties of water

Answer 30

1) It is POLAR (formed w/ polar covalent bonds and H bonds - partially charged intermolecular bonds) 2) EXPANDS in solid state (ice) 3) RESISTANT to temp change - high specific heat (insulative) 4) COOLS via evaporative cooling mechanism

Question 31

CHO CHO CHON CHONP

Answer 31

Carbs - CHO → Carbon, Hydrogen, Oxygen Lipids - CHO → Carbon, Hydrogen, Oxygen Proteins - CHON → Carbon, Hydrogen, Oxygen, Nitrogen Nucleic Acids - CHONP → Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus