Water (2.2)

Question 1

What kinds of bonds do Hydrogen and oxygen have in water?

Answer 1

Covalent bonds

Question 2

Why is water a bent molecule?

Answer 2

Because oxygen wants electrons so badly, it tugs electrons toward it in an unequal sharing of electrons. This gives O a negative charge and H a positive charge. (polar covalent bond)

Question 3

What are hydrogen bonds?

Answer 3

Hydrogen bonds are weak intermolecular forces, which give water its unique properties.

Question 4

How many electrons does oxygen have?

Answer 4

6

Question 5

How many electrons does hydrogen have?

Answer 5

1

Question 6

What causes a polar covalent bond?

Answer 6

this forms from the uneven sharing of electrons

Question 7

How do hydrogen bonds form?

Answer 7

They form when the negatively charged oxygen on one molecule is electrostatically attracted to the positive hydrogen on another

Question 8

What are the 4 properties of water?

Answer 8

Cohesive, adhesive, thermal, and solvent

Question 9

What is dipolarity?

Answer 9

Having different charges in one molecule

Question 10

What is cohesion?

Answer 10

Cohesion refers to the binding of 2 molecules of the same type

Question 11

Why does water cohere?

Answer 11

Water coheres because of hydrogen bonds

Question 12

What is transpiration?

Answer 12

The evaporative loss of water from plant leaves

Question 13

What is adhesion?

Answer 13

Adhesion refers to the binding of water to another polar molecule

Question 14

What is capillary action?

Answer 14

the ability for a liquid to flow through narrow spaces without the assistance of gravity

Question 15

How does water’s cohesion properties support life?

Answer 15

• it allows water to be transported to the top of trees through xylem vessels

Question 16

How does water’s adhesion support life?

Answer 16

• in leaves, water adheres to cellulose in the cell wall f leaves
• aids in drawing water up during capillary action

Question 17

Thermal properties of water

Answer 17

high specific heat capacity, high heat of vaporization, water as a coolant, and high boiling point

Question 18

What causes a high specific heat capacity in water?

Answer 18

H-bonds restrict water’s movement, which causes water to need a large amount of energy to change temperature. Water can absorb or lose great amounts of energy while keeping a stable temperature.

Question 19

How does high specific heat capacity in water support life?

Answer 19

• aquatic organisms can maintain homeostasis due to the stable temperatures of water.

Question 20

What causes water’s high heat of vaporization?

Answer 20

Water needs a large amount of energy to evaporate because H-bonds need to be broken.

Question 21

What causes water’s coolant properties?

Answer 21

Evaporation has a cooling effect. When a molecule evaporates, it takes a small amount of heat with it.

Question 22

How does water’s coolant properties support life?

Answer 22

• evaporating sweat helps humans maintain a steady body temperature.

Question 23

What are water’s boiling and freezing points?

Answer 23

100 C and 0 C. This is the temperature range for most organisms on Earth

Question 24

What are water’s solvent properties?

Answer 24

Many different substances can dissolve in water because of it’s polarity (ex. Na and glucose)

Question 25

How do water’s solvent properties sustain life?

Answer 25

Water’s solvent properties allow substances to be transported/carried while dissolved in blood and the sap of plants. Water carries dissolved chemicals, minerals, and nutrients needed to support life.

Question 26

What does hydrophilic mean?

Answer 26

Hydrophilic substances are attracted to water. All substances that dissolve in water are hydrophilic and polar (ex. Na and CL). Substances that water coheres to are also hydrophilic.

Question 27

What does hydrophobic mean?

Answer 27

Hydrophobic substances are insoluble in water. All lipids are hydrophobics, including fats and oils. Water cannot bond to hydrophobic substances.