Properties of Water

Where there is ________, there is __________!

Properties of Water

Where there is life, there is

Water!

I. Chemical Formula

• Organisms are _____% - _____% Water• The 6 most common atoms found in living things

(makes up about 99% of our body) are:1.2.3.4.5.6.

Acronym: _ _ _ _ _ _

I. Chemical Formula

• Organisms are 50% - 90% Water• The 6 most common atoms found in living things

(makes up about 99% of our body) are:1. Sulfur (S)2. Phosphorus (P)3. Oxygen (O)4. Nitrogen (N)5. Carbon (C)6. Hydrogen (H)

Acronym: SPONCH

II. Molecular Structure

O-

H+ H+

Water is a ___________ molecule (Has a ____________ at each end). The specific molecular structure of water leads to the different properties that we will talk about.

II. Molecular Structure

O-

H+ H+

Water is a polar molecule (Has a charge at each end). The specific molecular structure of water leads to the different properties that we will talk about. Note: Water is bent because oxygen has a higher electronegativity, therefore there is an unequal sharing of electrons in oxygen’s favor.

III. Properties of Water

1. Water is an excellent _________. Why?

Water is charged at both ends and can therefore, bond to any ________ molecule.

III. Properties of Water

1. Water is an excellent solvent . Why?

Water is charged at both ends and can therefore, bond to any charged molecule. H+ H+

O-

Salt: NaCl (sodium chloride)• When salt dissolves in water: Na+ separates from Cl- • Where would salt bond to water?

H+ H+---Cl-

Na+---O-

• Why is it biologically critical that water be an excellent solvent?

1. ______________

2. ______________

3. ______________

This diagram shows salt dissolving in water.

H+ H+---Cl-

Na+---O-

• Why is it biologically critical that water be an excellent solvent?

• Bloodstream (our blood is made of 50% water that dissolves/circulates nutrients)

• Waste excreted from our body is carried via water.

• Minerals/Nutrients absorbed by plants via water.

This diagram shows salt dissolving in water.

•Detergents

Detergents are special molecules because they are __________ (charged) on one end and __________ (uncharged) on the other end.

(-)

(No charge)

Example:

Phosopholipid

Sticks to ___________molecules

Sticks to _________molecules

•Detergents

Detergents are special molecules because they are polar (charged) on one end and

nonpolar (uncharged) on the other end.

(-)

(No charge)

Example:

Phosopholipid

Sticks to charged molecules

Sticks to nonpolar molecules.

Soap (detergent)

Polar end ---- H2O (Goes down drain)

Nonpolar end ---- Nonpolar substance(grease/oil)

(Pulled along with water)

• Hydrophobic: (Water-______) does not bond to water – has no charge).

• Hydrophilic: (Water-_______)Has an affinity to water – is charged.

III. Properties of Water (Cont.)

2. Water has Surface Tension: Water forms a ________ at the surface.

• Water has the ability to stick to a second water molecule. Called ___________. Water has a greater attraction to other water molecules than to the molecules in the air.

• Water sticks to another water molecule when a _____ charged hydrogen forms a hydrogen bond with a _______ charged oxygen.

• This type of bond is fairly weak.

III. Properties of Water (Cont.)

2. Water has Surface Tension: Water forms a blanket at the surface.

• Water has the ability to stick to a second water molecule. Called cohesion . Water has a greater attraction to other water molecules than to the molecules in the air.

• Water sticks to another water molecule when a + charged hydrogen forms a hydrogen bond

with a - charged oxygen.• This type of bond is fairly weak.

The Three States of Water

H+ H+---O-

-O--- H+ H+

Biological significance of water having surface tension:

This is a waterstrider that literally “walks on water”

Detergents disrupt surface tension! Why????

Dive Belly flop

VSOuch!

III. Properties of Water (Cont.)

3. Water has a high heat capacity • Holds on to heat well.• Resists temperature change. Why? A lot of ________

must be taken _______ to cool water or a lot of __________ must be put in to ________ water.

III. Properties of Water (Cont.)

3. Water has a high heat capacity • Holds on to heat well.• Resists temperature change. Why? A lot of energy

must be taken out to cool water or a lot of energy must be put in to warm water.

• Biological significance: Oceans maintain steady temps throughout year. Most ocean life cannot regulate body temp.

• Sweating (evaporation) creates a cooling effect!

III. Properties of Water (Cont.)

4. Ice Floats – Water changes density at 4°C• Colder water is more dense (_________) than warmer

water until 4°C. Because of the structure of ice, water molecules begin to spread out again and ice floats.

Lake in fall Lake in spring

(Temp. range: 4°- 7°) (Temp. range: 0°- 4°)

ICE___°C___°C___°C___°C___°C

___°C___°C___°C___°C___°C

III. Properties of Water (Cont.)

4. Ice Floats – Water changes density at 4°C• Colder water is more dense (_________) than warmer

water until 4°C. Because of the structure of ice, water molecules begin to spread out again and ice floats.

Lake in fall Lake in winter

(Temp. range: 4°- 8°) (Temp. range: 0°- 4°)

ICE 8 °C 7 °C 6 °C 5 °C 4 °C

0 °C 1 °C 2 °C 3 °C 4 °C

Biological Significance: Wildlife can survive winter!! Ice acts as an insulator.

• Biological Significance: With the changing of the seasons, this property of Water leads to a thermal overturn:

Melting of Ice:

0°C

4°C

2°C

6°C

Nutrients (phosphates and nitrates) are circulated throughout the lake for living things.

III. Properties of Water (Cont.)

5. Water has adhesive and cohesive properties.

• Water sticks to _________. (Cohesion)• Water sticks to _________ molecules. (Adhesion)

III. Properties of Water (Cont.)

5. Water has adhesive and cohesive properties.

• Water sticks to water . (Cohesion)• Water sticks to charged molecules. (Adhesion)

Water sticks to charged xylem tissue in plants.

Water sticks to water

Biological significance: Water can travel up trees from roots to leaves!