UNIT _____: Water Name: _____________________

Water is a polar covalent molecule which can form intermolecular hydrogen bonds.

Describe the structure of an atom (in terms of protons, neutrons and electrons).
Contrast covalent, ionic and hydrogen bonds.
Write the molecular formula for water and draw the atomic structure of the molecule.
Describe the cause and effect of the polar nature of water.
Describe where and how water is able to form hydrogen bonds.

The theory that hydrogen bonds form between water molecules explains the properties of water.

List emergent properties that result from water molecules joining together via hydrogen bonds.
State why scientists cannot prove without a doubt that hydrogen bonds exist between water molecules.

Cohesion of water molecules creates surface tension which can support small plants and animals.

Define cohesion and surface tension.
Outline an example of the cohesive property of water being of benefit to life.

The polarity of water gives its adhesive properties that are important to exchange surfaces.

Define adhesion.
Outline an example of the adhesive property of water being of benefit to life.

Both adhesion and cohesion allow water to travel along tubes such as xylem vessels.

Explain capillary action in terms of adhesion and cohesion.
Outline how water moves into, through and out of a vascular plant.

Water has a high specific heat capacity which makes it resistant to changes in temperature.

Define specific heat capacity.
Describe why water has a high specific heat capacity.
Outline a benefit to life of water's high specific heat capacity.
Compare and contrast the physical properties of methane and water.

Explain why water and methane have different thermal properties based on their molecular structures.

Heat absorbed during the evaporation of water provides living organisms with a cooling mechanism.

Define evaporation.
Explain sweating as a mechanism to cool the body.

Substances can be hydrophilic or hydrophobic.

State that polar and ionic molecules are hydrophilic.
State that non-polar, non-ionic molecules are hydrophobic.
Given a diagram of a molecular structure, determine if the molecule is hydrophilic or hydrophobic.
State if the following molecules are hydrophobic or hydrophilic: glucose, amino acids, cholesterol, fats, oxygen, and sodium chloride.

Water acts as a solvent for ionic and polar substances.

Contrast ion with atom.
Define anion and cation.
Explain why water is such a good solvent.
List the types of molecules that water will dissolve.

Blood in animals and sap in plants are mainly water and are used as transport media.

List the materials transported in xylem and phloem saps.
Outline the mechanism of transport in the blood of the following molecules: glucose, amino acids, cholesterol, fats, oxygen, and sodium chloride.

Hydrogen bonds give ice an open structure with a lower density than liquid water, as a result ice will float on liquid water providing insulation for aquatic life.

Compare and explain the density of ice and liquid water.
Outline an example of the density of ice being of benefit to life.

Water is transparent allowing light to penetrate for photosynthesis by aquatic photoautotrophs.

Outline an example of transparent property of water being of benefit to life.

Water is a metabolite in biochemical reactions.

Define metabolite.
Compare water’s role in condensation and hydrolysis reactions.

Chemistry Basics

ATOM: The smallest unit of matter that still has the properties of an element

ION: A charged atom that forms when one or more valence electrons are transferred from one atom to another.

BOND: an attraction between atoms, ions or molecules that enables the formation of chemical compounds.

COVALENT BOND

A chemical bond that involves the sharing of electron pairs between atoms

Non-polar covalent

A bond in which two nonmetals pull at shared electrons with EQUAL FORCE

Polar Covalent

A bond in which two nonmetals interact resulting in an UNEQUAL SHARING of electrons.

IONIC BOND

The force of attraction between two oppositely charged ions

HYDROGEN “BOND”

A weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.

Water Structure

INTERMOLECULAR HYDROGEN BONDS

Hydrogen Bond Theory: Proof Beyond all Doubt?

COHESION

ADHESION

SPECIFIC HEAT CAPACITY

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.

Internal Environment

Habitat

COMPARING WATER TO METHANE

	METHANE	WATER
FORMULA
BONDING
POLARITY
HEAT CAPACITY
IMPLICATIONS

SOLUBILITY

It is water's polarity that makes it such an excellent solvent. Water molecules have a polar arrangement of the oxygen and hydrogen atoms—one side (hydrogen) has a slight positive electrical charge and the other side (oxygen) has a slight negative charge. This allows the water molecule to become attracted to many other different types of molecules.