Chapter 2- Chemistry Review & water

Question 1

What is matter composed of?

Answer 1

Elements (Carbon-Nitrogen-Calcium-Sodium-Iron)

Question 2

What is an element and how is it different from an atom?

Answer 2

Substance that cannot be broken down by a chemical reaction. Atoms are 2 or more elements combined.

Question 3

4 most important elements in living organisms

Answer 3

96% of all living things (CHON)

Question 4

essential elements vs trace elements

Answer 4

Essential are CHON.
Trace are like Iodine, calcium, potassium, etc….- minute (MYNOOT) quantities

BOTH are required to live a health life and reproduce

Question 5

The 3 subatomic particles of an atom?
what are their charges?
where is each located?

Answer 5

Protons (+)————-
packed together to make a nucleus
Neutrons (Neutral)——

Electrons (-) —– floating around the nucleus (cloud or rings(bore))

Question 6

How does potential energy vary from an electron in the first entry level to one located in the third energy level?

Answer 6

It can absorb energy when it moves further out…..

When electrons loses energy it moves closer to the nucleus and releases heat.

Question 7

does an electron GAIN or LOSE potential energy as it moves to a higher energy level?

Answer 7

Gain

Question 8

does an electron GAIN or LOSE potential energy as it moves to a higher energy level?

Answer 8

Gain

Question 9

Which subatomic particles are most responsible for the chemical behavior of an atom?

Answer 9

Electrons

Question 10

covalent bonds vs. ionic bonds vs hydrogen bonds

Answer 10

Covalent- Shares pairs of Valence electrons

Ionic- A charged atom (MOLECULE)
attractions between Cations (lost ions (+))
Anions (Gains ions (-))

Hydrogen- Attraction between partial bonds
Forms when a hydrogen atom covalently bonds to one electronegative atom to another electronegative atom.

Question 11

which type of bond holds most of biological molecules together?

Answer 11

Covalent

Question 12

what does it mean for an atom to be ELECTRONEGATIVE?

Answer 12

The electrons are NOT shared equally

Question 13

ELECTRON SHARING DIFFER-
non polar covalent bond
polar covalent bond

Answer 13

NON POLAR- Electrons are shared equally

POLAR- Shares Partial positive electrons

Question 14

which atom in the water molecule is electronegative

Answer 14

Oxygen- Takes more electrons from hydrogen than it gives back.

Question 15

what type of bond occurs WITHIN water molecules.

BETWEEN water molecules

Answer 15

Within- Hydrogen bonds

between- Polar Covalent Bonds

Question 16

why is water a POLAR molecule?

Answer 16

There is an uneven distribution of electrons.

The electrons spend more time closer to oxygen than hydrogen.

Question 17

What is an ION?

What term refers to an ION with a positive charge - negative charge

Answer 17

Charge of an atom (+ or -)

Positive Ion has more protons than electrons
Negative Ion has less protons than electrons
NEUTRAL- Has equal amounts

Question 18

How does a neutral atom become an ION?

Answer 18

Removing or adding electrons

Question 19

which bond entails an attraction between partial Charges?

Answer 19

Hydrogen

Question 20

Reactants vs. Products- Give some reaction

Answer 20

REACTANTS
(1. H-H ) o-h h
( + 0-0 )= FORMS- 2 H2O’s
(2. H-H ) o-h h
^^^ PRODUCTS

Question 21

what type of bonds hold atoms together in a water molecule?

Answer 21

Hydrogen Bonds

Question 22

What characteristics of water enables hydrogen bonds to form between water molecules?

Answer 22

High boiling points, High specific heat, cohesion and adhesion and density.

Question 23

Cohesion vs. Adhesion

Answer 23

COhesion- Bonding between like substances
water to water

Adhesion- Bonding between different substances.
water to plant cell walls

Question 24

What is surface tension?

Answer 24

a measure of force to break the surface of water

Question 25

what accounts for waters high surface tension

Answer 25

Waters Hydrogen bonding between the molecules

Question 26

what is specific heat?

How is water high specific heat important to life?

Answer 26

amount of heat that MUST be AbSORBED or LOST for temperature to change 1’

Minimizes temp fluctuations to within limits that permit life.

Question 27

Evaporative cooling?

How is it important to living organisms?

Answer 27

Liquid to gas
as a liquid evaporates, its remaining surface cools
Helps maintain body temp.

Question 28

why is ice less dense than liquid water?

Answer 28

ICE- the hydrogen bonds are further apart.

liquid water- there is less room (more packed together)

Question 29

why is it important to life that ice floats?

Answer 29

It would make it impossible for life in lakes and rivers, would cause the entire lake to freeze over killing all of its inhabitants.

Question 30

Solute vs.
Solvent vs.
Solution

Answer 30

solute- substance that is being dissolved

solvent- agent used to dissolve the solute

solution- The homogeneous mixture of the two

Question 31

How does waters polarity contribute to its solvent capabilities?

Answer 31

Can dissolve CHARGED &or Polar molecules.

Question 32

The changes in the concentrations of which two ions can drastically affect cell chemistry.

Answer 32

Hydrogen H(+)
Hydoxide HO(-)

Question 33

How does Hydrogen ions (H+) concentration vary from an ACID to a BASE

Answer 33

ACIDS- Increase H+

BASES-Reduce H+

Question 34

when interpreting the pH scale, why is it important to know that it is a LOGARITHMIC SCALE?

Answer 34

??????

Question 35

why are BUFFERS important?

Name two locations BUFFERS are found?

Answer 35

Can resist pH change, can neutralize small amounts of added acids or bases.

Human blood has buffers, household products.

Question 36

what are the two types of substances that form a BUFFER?

Answer 36

Weak acid and a weak base

weak acids and salt of that weak base

Question 37

How does a buffer react if the pH is too alkaline? (basic)

How does a buffer react if the pH is too acidic?

Answer 37

???