A1.1 Water Flashcards
List reasons why water is a substance on which life depends
life needs to interact with each other in a liquid solvent – water
what is the structure of an atom
Electrons on the valence shells, protons and neutrons inside the nucleus
What is a covalent bond
A sharing of electrons between two non-metals
What is an ionic bond
A transfer of electrons between a nonmetal and a metal
Explain how the sharing of electrons between atoms in a
noncovalent bond
They share their electrons unevenly, one side has a slightly negative charge and another side has a slightly positive charge.
State the location of the polar covalent bond within a water molecule
The oxygen atom has a slightly negative charge while the 2 hydrogens have a slightly positive charge
What makes an atom more electronegative
The smaller the atom and the more positive it is (opposites attract)
Explain why a smaller atom + more positive atom is more electronegative
A more positive atom means it has more protons = attracts more electrons
smaller means less shells = a stronger pull on the other electrons
what is a hydrogen bond
a weak attraction between polar molecules (slight positive hydrogen atom and slight negative charged atom)
Are covalent bonds stronger or hydrogen bonds
covalent bonds (hydrogen bonds are weaker because they are an intermolecular bond)
The cause of the formation of hydrogen bonds between water molecules
When water atoms are near each other hydrogen bonds start to form. A dotted line is drawn to show the attraction between the Slightly positive Hydrogen and the slightly negative oxygen
what is the importance of hydrogen bonds in water molecules
made and broken very easily, the large amount of bonds contribute to the stability of the earth
What is cohesion
cohesion is an attraction between water molecules due to hydrogen bonding
what is adhesion
adhesion is an attraction between water and other substances due to hydrogen bonding and different substances
what is surface tension
how difficult it is to break or stretch apart the surface due to cohesion
How does water move through the Xylem in a vascular plant
Root Absorption: Roots take in water from the soil.
Xylem Transport: Water moves up the plant through the xylem tubes.
Transpiration Pull: Water evaporates from leaves, pulling more water up.
Cohesion & Adhesion: Water sticks to itself and xylem walls, helping it move upward.
what is the cause of surface tension
there is a strong cohesive force (hydrogen bond) between water molecules that needs to be overcome
Benefit to living things that result from surface tension
Allows small insects to walk on water.
Helps plants draw water through roots.
Supports water movement in cells.
polar meaning
one part is slightly positive and one part is slightly negative
Outline the cause of capillary action
Liquid moves through narrow tubes.
Driven by adhesion, cohesion, & surface tension.
Works against gravity.
Adhesive forces > cohesive forces.
Capillary action in the plant xylem
Adhesion: Keeps water attached to xylem walls, preventing it from falling.
Cohesion: Allows water to move up in a continuous stream.
Surface Tension: Maintains water’s structure in the xylem.
capillary action in soil
Porous Soil: Has spaces for water.
Attraction: Water sticks to polar substances in soil.
Capillary Action: Pulls water up, even against gravity.
what is a solvent
the liquid in which a solute dissolves
What is a solute
the substance that dissolves in a solvent
What is solution
a mixture of one or more solutes dissolved in a solvent
what is solvation
The process of the solute dissolving in the solvent
Why is water able to dissolve charged and polar molecules
It’s a universal solvent
Polarity: Water has a positive and negative end.
Hydrogen Bonds: Attracts positive and negative ions
What does the term hydrophilic mean
Dissolves in water, and forms strong bonds with water (hydrogen bonds, ion-dipole).
What does the term hydrophobic mean?
Does not dissolve, clusters in water due to weak or no interactions.
What is an example of a function of a hydrophobic and insoluble molecule?
-Steroid hormones
-Plasma membrane and nuclear membrane
-Certain parts of proteins
Because steroids are hydrophobic, they can pass straight through the nuclear membrane and interact with DNA
What is an example of a function of a hydrophilic and soluble molecule?
Glucose
Ions
Amino acids
Proteins e.g. enzymes
This ensures they can be transported easily. Making water an excellent transport medium.
what is the role of water as a medium for metabolism
- cytosol is a liquid found in the cytoplasm
- It contains water and dissolved salts, fatty acids, sugars, amino acids, and proteins such as enzymes
- the substances are needed to fulfill the metabolic process, if they aren’t hydrophilic it wouldn’t be possible.
-water is needed to dissolve the reactants and enzymes so they can react
What is the role of water as a medium for transport in vascular plants
-Dissolved solutes can be transported in solution around the body of an organism.
-the dissolved mineral ions are transported in the xylem from the roots to the leaves
-Dissolved sugars produced in photosynthesis are transported in the phloem from source to sink
What is the role of water as a medium for transport in animal blood
- Dissolves Nutrients and Gases like glucose, amino acids, ions) and respiratory gases (oxygen, carbon dioxide) for easy transport in blood.
-Transport of Waste: Waste products (urea, carbon dioxide) dissolve in water, enabling their removal from the body.
what is High specific capacity
require a greater change in energy to change their temperature
Water has a high specific capacity. Think back to your chemistry, what does this mean?
hydrogen bonds between water molecules, it takes a lot of energy to raise the temperature of water, as the H-bonds can absorb a lot of the energy.
Why do you think this makes water a good habitat for animals?
This means water doesn’t experience rapid changes in temperature.
list physical properties of water that are consequential for animals in aquatic habitats
-High Specific Heat Capacity
-High Surface Tension
-density and buoyancy
High Thermal conductivity
what is buoyancy
- Buoyancy is an upward force applied to an object that is immersed in a fluid. If the buoyant force of the fluid is greater than the object’s weight, the object will float.
Physical properties of buoyancy
An object with a lower density than the fluid experiences a buoyant force greater than gravity, causing it to float.
An object with a higher density than the fluid experiences a buoyant force weaker than gravity, causing it to sink.
What is viscosity
-Viscosity is a measure of a fluid’s tendency to flow.
-Viscosity is due to the amount of friction the molecules of a liquid experience as they flow over each other.
-A thick fluid is more viscous and a thin fluid is less viscous.
Compare the viscosity of air to water to blood
Air: Lowest viscosity; allows fast, easy movement.
Water: Moderate viscosity; provides some resistance but supports aquatic life.
Blood: Highest viscosity; enables effective circulation for nutrient and oxygen delivery in animals.
What is thermal conductivity
Thermal conductivity is a material’s ability to conduct heat.
-High Thermal Conductivity: Good heat conductors (e.g., metals) transfer heat quickly.
-Low Thermal Conductivity: Poor conductors (e.g., wood, rubber) insulate by slowing heat transfer.
What are some low-conductive materials
styrofoam and air
what are some high-conductive materials
water and copper
How does the ringed seal use the physical properties of water to live
-Buoyancy in water helps the seal stay afloat with minimal energy use.
-Water’s viscosity creates resistance, so the seal has streamlined adaptations for efficient swimming.
-Water has higher thermal conductivity than air, so the seal insulates itself with blubber to maintain body temperature.
-Water’s high specific heat means it changes temperature slowly, providing a stable habitat for the seal.
How does the black-throated loon use the physical properties of water to live
-Buoyancy in water enables the bird to float with minimal energy expenditure.
-When flying, the bird must expend energy to stay aloft.
-Air’s low viscosity allows the bird to move easily through it.
-The bird loses less body heat to the air due to its low thermal conductivity.
-However, air’s low specific heat means its temperature can change rapidly.
What is the specific heat capacity
Specific heat capacity is the quantity of heat needed to raise the temperature of a chemical per unit mass.
what is the benefit to the life of the high specific heat capacity of water
As a result of its high specific heat capacity, water heats up or cools down very slowly. This provides for a stable internal environment and habitat of living things.
