1 chapter 3: water and the fitness of the environment think, pair, share:
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Chapter 3: Water and the Fitness of the Environment
THINK, PAIR, SHARE:
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Figure 3.1
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
5
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
H O
wants to fill this
H H
Covalent Bonding
Chapter 2 – The Chemical Context of Life AIM: Why is water important to life?
Chapter 3 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
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(a)
(b)
Name(molecularformula)
Electron-shell
diagram
Structuralformula
Space-fillingmodel
Hydrogen (H2). Two hydrogen atoms can form a single bond.
Oxygen (O2). Two oxygen atoms share two pairs of electrons to form a double bond.
H H
O O
Figure 2.11 A, B
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
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Name(molecularformula)
Electron-shell
diagram
Structuralformula
Space-fillingmodel
(c)
Methane (CH4). Four hydrogen atoms can satisfy the valence ofone carbonatom, formingmethane.
Water (H2O). Two hydrogenatoms and one oxygen atom arejoined by covalent bonds to produce a molecule of water.
(d)
HO
H
H H
H
H
C
Figure 2.11 C, D
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
H
H
Oxygen
+
+
––
––
Because oxygen (O) is more electronegative than hydrogen (H), shared electrons are pulled more toward oxygen.
This results in a partial negative charge on theoxygen and apartial positivecharge onthe hydrogens.
AIM: Why is water important to life?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
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AIM: Why is water important to life?
Chapter 2 – The Chemical Context of Life
Fluorine has the highest
electronegativity. Why not neon or helium?Neon/Helium have a full
valence shell and therefore are already
stable all by themselves and will not attract
electrons to be stable.In biology, we will focus on elements with high
electronegativity like oxygen and nitrogen.
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Polar Covalent Bond
AIM: How do atoms interact with each other?
Chapter 3 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Non-polar covalent bond
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
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AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Hydrogen Bonds
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
ionsCation vs Anion
The sodium and chloride ions are now attracted to each other and form an
ionic bond.ionic bond = bond between two
oppositely charged ions
Ionic Bond
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Salt crystals
-Na+Cl- crystals are repeating arrays of Na+ and Cl- held together by the
electromagnetic force.-general name given to ANY ionic compound (not just sodium chloride
(Na+Cl-) held together in a lattice structure. Ex:
Na+Cl-
K+Cl-
Mg2+Cl2-
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Van der waals interactions• Even non-polar molecules can have some positively and negatively charged region briefly and can very weakly bind to another.
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Figure 1. Two non-polar molecules (say H2) come into close proximity
Figure 2. By chance, the position of the electrons around one of the molecules (the one to the left) are more on one side of the molecule than the other causing one side to be slightly negative and the other side to be slightly positive.
Figure 3. This will then induce a dipole in the neighboring molecule as the neighboring molecule’s electrons will be attracted to the slightly positive region of the first molecule resulting again in an ever so slightly negative side and an ever so slightly positive side. Of
course, the negative and positive will form a very weak interaction.
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◦ Reinforce the shapes of large molecules◦ Help molecules adhere to each other
Plasma membrane are stabilized by the additive affect of Van der Waals interactions between non-polar fatty acid tails of
phospholipids.
H bonds
The two strands of a DNA molecule are held together tightly by the additive affect of many, many weak
Hydrogen Bonds
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of LifeAIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Fig. 2-UN7
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of Life
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Fig. 2-UN11
AIM: How do atoms interact with each other?
Chapter 2 – The Chemical Context of Life
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Water-conductingcells
Adhesion
Cohesion150 µm
Directionof watermovement
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
How is water transported against gravity in plants?
Water-conductingcells
Adhesion
Cohesion150 µm
Directionof watermovement
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
How is water transported against gravity in plants?
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
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A measure of how well a substance resists change in temperatures
1 kcal = 1,000 calories; amount of heat needed to raise the temp of 1kg of water
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Specific heat of iron: 0.1 cal/g/oC
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Water, because of it H-bonding (cohesive nature) has a very high specific heat
relative to other molecules.
It is difficult to get the water molecules to vibrate since they are all sticking to each
other. The H-bonds need to be broken.
Think about this analogy: is easy to push a single student and get them moving fast,
but if you all hold hands, it becomes more difficult as I would need to break those
bonds.
Helps organisms resist change in temperature!!
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Water has a relatively high heat of vaporization because the hydrogen
bonds of the water that must be overcome in order for evaporation to
occur
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Liquid waterHydrogen bonds
constantly break and re-form
IceHydrogen bonds are stable
Hydrogen bond
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Solvent: the dissolving agent in a solution
Solute: the substance being dissolved
Solution: a homogeneous mixture Aqueous solution: water is the solvent
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
“Cage” of water molecules surrounding each dissolved substance
Hydration shell
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
This oxygen is
attracted to a
slight positive
charge on the
lysozyme
molecule.This oxygen is attracted to a slight negative charge on the lysozyme molecule.
(a) Lysozyme molecule
in a nonaqueous
environment
(b) Lysozyme molecule (purple)
in an aqueous environment
such as tears or saliva
(c) Ionic and polar regions on the protein’s
Surface attract water molecules.
+
–
Figure 3.7
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Rule of thumb: LIKE DISSOLVES LIKE
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
40
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
Rule of thumb: LIKE DISSOLVES LIKE
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
AIM: Why is water important to life?
Chapter 3 – Water and the Fitness of the Environment
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How would you make a 0.5-molar (0.5 M) solution of sodium chloride (NaCl)?
1. Find moles 2. Convert moles to grams (factor label method)3. Add enough water to make 1 L
Molarity = moles of solute liter of solution
Moles = M * L
1. Moles = 0.5 M * 1 L
= 0.5 moles
2. 0.5 moles * _________g 1 mole
Remember 1 mole = formula mass
58.5 = 29.3 g of NaCl and fill with water to 1 L
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ck72+nerd
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How many grams of acetic acid (C2H4O2) would you use to make 10 L of a 0.1 M aqueous solution
of acetic acid? 1. Find moles 2. Convert moles to grams (factor label method)
Molarity = moles of solute liter of solution
Moles = M * L
1. Moles = 0.1 M * 10 L
= 1 mole
2. 1 mole * _________g 1 mole
Remember 1 mole = formula mass
= 60 g of acetic acid 60
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What is the molarity of a solution made by dissolving 2.5 g of NaCl in enough water to make
125 ml of solution? 1. Convert grams to moles2. Find molarity
Molarity = moles of solute liter of solution
1. 2.5 g * 1 mole g
Remember 1 mole = formula mass
58.5 = 0.0427 moles
2. Molarity = 0.0427 moles 0.125 L
Molarity = 0.34 M NaCl
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AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
H2O H+
+ OH-
Hydrogen ion(aka… a proton)
Hydroxide ion
The oxygen atom is more electronegative than the hydrogens and pulls the shared electrons away from them, which can cause one of the hydrogens (a proton) to fall off.
H
Hydroniumion (H3O+)
H
Hydroxideion (OH–)
H
H
H
H
H
H
+ –
+
Figure on p. 53 of water dissociating
H2O H+ +
OH-
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
It will transfer from one water to another to form H3O+
This change can significantly change the pH of an aqueous solution
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
Chapter 2 - The Chemical Basis of Life AIM: pH?
Logarithms (logs)The log of a number is simply
how many powers of 10 you can pull out of that number.
Ex. log 1000= 3 because you can pull three powers of 10 out
of 1000 (10 x 10 x 10) or 103 = 1000
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
Chapter 2 - The Chemical Basis of Life AIM: pH?
Logarithms (logs)Ex. Log 100,000
= 5 because you can pull out 5 powers of 10 from 100,000 or 105 =
100,000.
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
Chapter 2 - The Chemical Basis of Life AIM: pH?
Logarithms
log 102= log 100 =
log 103= log 1000 =
log 104= log 10,000 =
log 105=
log 106=
log 10-1= log .1 =
log 10-2=
log 10-3=
log 10-4=
23456-1-2-3-4
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
Chapter 2 - The Chemical Basis of Life AIM: pH?
Then if you take the negative log…
The signs switch
-log 102=
-log 103=
-log 104=
-log 105=
-log 106=
-log 10-1=
-log 10-2=
-log 10-3=
-log 10-4=
-2-3-4-5-61234
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
pH = -log [H+]
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
What if the pH is 10 X higher?
pH = -log [H+][H
+] = 10-6 M
pH = -log [H+]
x = -log [10-6M]pH = 6
pH = -log [10-7M]pH = 7
[H+] = 10-7 M
What if the pH is 10 X higher?
1. As [H+] goes up, pH goes DOWN
3. A change in 1 pH corresponds to a 10-fold change in [H+]2. As [H+] goes down, pH goes UP
How many times more
acidic is lemon juice than urine? 10,000X more acidic
How many times more basic is
milk of magnesia (pH
11) compared to seawater (pH
8)? 1000X more basic
Incr
easi
ngly
Aci
dic
[H+]
> [
OH
–]
Incr
easi
ngly
Bas
ic[H
+]
< [
OH
–]
Neutral[H+] = [OH–]
Oven cleaner
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
pH Scale
Battery acid
Digestive (stomach) juice, lemon juiceVinegar, beer, wine,colaTomato juice
Black coffee RainwaterUrine
Pure waterHuman blood
Seawater
Milk of magnesia
Household ammonia
Household bleach
Figure 3.8
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
1. What does the pH value tell us about the
solution? 2. What happens to the
pH as the [H+] increases?
3. If the pH of a solution is increased by three pH units, how has the [H+]
changed?
The H+ (free proton) concentration [H+]
decreases
1000x lower [H+]
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment
0
12
34
56
78
910
1112
1314
Moreacidic
AcidrainNormalrain
Morebasic
Figure 3.9
AIM: How does pH affect living organisms?
Chapter 3 – Water and the Fitness of the Environment