Module 3.1 H Bonds & Properties of Water Flashcards
Waters life-giving properties
- Ice is less dense than water
- Water changes temperature slowly
- Water exhibits cohesion
- Water is an excellent solvent
Water is essential for life and makes up a significant portion of the earth’s surface.
What percentage of the earth is covered in water?
70%
What percentage of our cells is made up of water?
70-95%
Water is primarily found in the cytoplasm/cytosol or intracellular fluid (ICF).
Water bathes our cells in
extracellular fluid (ECF)
Extracellular fluid (ECF)
the fluid outside all cells of the body. Is composed primarily of interstitial fluid and plasma, and plays a crucial role in maintaining homeostasis and facilitating the exchange of substances between cells and their environment.
Middle of a cell is called a
Cytoplasm or the cytosal or “the soup.” It’s a watery environment
What is the structure of water in terms of polarity?
Water is a polar molecule
Oxygen is electronegative, attracting electrons, making oxygen partly negative and hydrogen partly positive.
Oxygen in water is
electronegative
Water has a big, strong
Oxygen
Water will always pull electrons towards
the oxygen
Water attracts the electrons of the
single covalent bonds
Water is what kind of bond?
A polar covalent bond.
Polar covalent bond has a difference of
polarity
The oxygen in water is partly
negative
The hydrogen in water is partly
positive
What type of bond forms between a partly negative atom of a molecule and a partly positive hydrogen of a different molecule?
Hydrogen bonds
These bonds occur in polar covalent bonds, typically involving oxygen or nitrogen.
Water molecules can form up to how many hydrogen bonds?
4 bonds with 4 different water molecules
Hydrogen bonds must have an electronegative atom attached to a
hydrogen
In living organisms, most hydrogen bonds involve molecules with
–OH or –NH
Are hydrogen bonds strong or weak?
Weakest of all bonds
Hydrogen bonds are usually represented by dashed or dotted lines.
What are the three states of matter in which water can exist?
Solid, Liquid, Gas
Water’s hydrogen bonds keep it liquid over a temperature range of 0 – 100 °C.
Hydrogen bonds between water molecules keep it liquid over a range of
0 – 100oC
Water is known as the
solvent of life
Water dissolves by forming a what around molecules?
hydration shell
What is a hydration shell?
A structure formed around molecules in water
It occurs when partly positive hydrogens attract chloride ions and partly negative oxygens attract sodium ions.
When water dissolves sodium chloride, what happens?
Partly positive hydrogens are attracted to the chloride ions
Partly negative oxygens are attracted to the sodium ions
Polar molecules such as sugar and ammonia also
dissolve in water
Around the solute, water forms
spheres of hydration
What is the term for molecules that are ‘water-hating’?
Hydrophobic
Examples include oil.
What is the term for molecules that are ‘water-loving’?
Hydrophilic
Water soluble vitamins are hydrophilic.
Water soluble vitamins are
hydrophilic
Hydrophilic molecules are
polar
All polar molecules are
“water-loving,” so they can dissolve in water
Hydrophobic molecules are
nonpolar
Hydrophobic molecules cannot dissolve/interact in/with water because they cannot
form hydrogen bonds with water
Molecules that are both “water-loving” and “water-hating”
Have a hydrophobic end and a hydrophilic end
Evaporation
transitioning from a liquid state to a gaseous state
Evaporation occurs
at the surface of a liquid
In order for evaporation to occur, Molecules must be moving fast enough to
break the hydrogen bonds holding them together
Boiling is similar to
evaporation
Boiling occurs
throughout the liquid
Boiling is a
quick process
What is the heat of vaporization?
The amount of heat needed to convert 1 gram of substance from liquid to gas
Water requires about 560 calories of heat to evaporate 1 gram.
Water has a high
heat of vaporization
To evaporate water, water needs
about 560 calories of heat to evaporate 1 gram of water
Specific heat is the
amount of heat needed to raise 1 gram of water 1oC
Water has high
specific heat
Water takes a long time to
heat up and cool down
Water stays liquid over a wide
range of temperatures
What is the boiling point of water?
100 °C
This boiling point is much higher than that of other nonpolar molecules of similar size.
The boiling point of water is much higher than
other nonpolar molecules of similar size
Cohesion
the result of hydrogen bonds between water molecules. So, water sticking to water
Cohesion creates
surface tension (why water strides can ride at the top of water or little water droplets on leaves)
What is cohesion in relation to water?
The sticking together of water molecules.
It results from hydrogen bonds between water molecules.
What creates surface tension in water?
Stronger hydrogen bonds at the surface
Surface tension occurs when water molecules at the surface bond more strongly with adjacent molecules.
Surface tension occurs when
water molecules at the surface form stronger hydrogen bonds with the water molecules on either side
Adhesion
Occurs when hydrogen bonds form between water molecules and other polar molecules. So, water sticking to other different molecules
What is adhesion in relation to water?
The sticking of water molecules to other polar molecules
This occurs due to hydrogen bonds forming between water and different molecules.
Water is a good what and what?
Lubricant and cushion
Why is water considered a good lubricant?
It reduces friction in joints and around organs
Examples include the joints of the knee and around the heart.
What role does water play as a cushion in the body?
It cushions the brain and is in the amniotic fluid that protects the fetus
Amniotic fluid is an example of water cushioning.
