WATER
CHAPTER 2 P. 47-49
CHEMISTRY REVIEW
• BONDS
Electronegative atoms atoms
with a strong attraction for
electrons….greedy!
• COVALENT
• SHARING OF ELECTRONS
• STRONG
• EQUAL SHARING=NON-POLAR COVALENT
• UNEQUAL SHARING=POLAR COVALENT
• IONIC
• ATTRACTION BETWEEN TW0 CHARGE ATOMS OR MOLECULES
• POSITIVE= CATION
• NEGATIVE= ANION
• CHARGES CANCEL=NEUTRAL IONIC COMPOUND
• DISSOCIATES IN WATER
INTERMOLECULAR FORCES
• HYDROGEN BONDS (NOT A “TRUE” BOND)
• BETWEEN THE HYDROGEN ATOM IN ONE MOLECULE
AND AN ELECTRONEGATIVE ATOM IN ANOTHER
MOLECULE (O, F, N)
• VAN DER WAALS FORCES
• ATTRACTION BETWEEN TWO POLAR MOLECULES
• (OPPOSITES ATTRACT)
WATER IN BIOLOGICAL SYSTEMS
• BIOCHEMICAL
• 80% OF A LIVING ORGANISM COMPOSED OF WATER
• ¾ OF EARTH COVERED IN WATER
• HUMANS ARE ABOUT 60% WATER
• 2 REASONS WHY WATER IS IMPORTANT
1. MAJOR COMPONENT OF CELLS (70-95% OF MASS OF CELL)
2. PROVIDES ENVIRONMENT FOR AQUATIC ORGANISMS TO LIVE
STRUCTURE OF WATER MOLECULE
• H2O TWO HYDROGEN ATOMS COVALENTLY BONDED
TO ONE GREEDY OXYGEN
• OXYGEN IS ELECTRONEGATIVE
• UNEQUAL SHARING OF HYDROGEN’S ELECTRONS
(ELECTRONS SPEND MORE TIME AROUND OXYGEN'S
ORBITALS)=POLARITY
• HYDROGENS IN WATER MOLECULE HAVE A SLIGHTLY +
CHARGE
• OXYGEN IN WATER MOLECULE HAS A SLIGHTLY – CHARGE
• DIPOLE SMALL CHARGES ON DIFFERENT ATOMS WITHIN
A SINGLE MOLECULE; UNEQUAL DISTRIBUTION OF A
CHARGE
• WATER HAS 3 DIPOLES…2 POSITIVE AND 1 NEGATIVE
HYDROGEN BONDING & WATER
• HYDROGEN BONDS RESTRICT MOVEMENT OF LIQUID WATER
• LIQUID WATER
• CONSTANTLY FORMING AND BREAKING HYDROGEN BONDS
• DENSE
• SOLID WATER
• HYDROGEN BONDS BECOME FIXED (STUCK)
• LESS DENSE THAN LIQUID
• WATER’S POLARITYHYDROGEN BONDING UNIQUE
PROPERTIES OF WATER
1. SOLVENT PROPERTIES
2. THERMAL PROPERTIES
THING TO KNOW:
ROLE OF WATER IN LIVING ORGANISMS IN
REFERENCE TO…..
1. SOLVENT ACTION
2. SPECIFIC HEAT CAPACITY
3. LATENT HEAT OF VAPORIZATION
SOLVENT PROPERTIES OF WATER
• DIPOLES ON WATER MOLECULES ENABLE MOLECULES TO SURROUND OTHER POLAR OR IONIC COMPOUNDS
• I.E. SODIUM CHLORIDE IN WATER
• POLAR MOLECULES AND IONS CAN DISSOLVE
• GOOD SOLVENT
• THIS ALLOWS WATER TO TRANSPORT SUBSTANCES AROUND BODY OF ORGANISMS
• EXAMPLES:
• MAMMALS  BLOOD PLASMA IS MOSTLY WATER CARRYING GLUCOSE, OXYGEN, AND IONS (NA+)
• LYMPHATIC, DIGESTIVE, AND EXCRETORY SYSTEMS
• PLANTS  NUTRIENTS FROM SOIL TO ALL PARTS OF THE PLANT
• VASCULAR TISSUE
• ENABLES WATER TO BE A MEDIUM FOR METABOLIC REACTIONS
• CYTOPLASM OF CELLS
• MATRIX OF MITOCHONDRIA
• STROMA OF CHLOROPLAST
THERMAL PROPERTIES OF WATER
WATER….
• IS LIQUID AT NORMAL EARTH TEMPERATURES
• H-BONDS PREVENT WATER MOLECULES FROM FLYING
AWAY FROM EACH OTHER (LIKE A GAS)
• BETWEEN 0* AND 100* WATER IS LIQUID
• FORMING AND BREAKING H-BONDS CONSTANTLY
• TRANSITORY BONDS
• HYDROGEN SULFIDE (H2S) SIMILAR STRUCTURE TO
WATER BUT GAS AT ROOM TEMP. B/C IT LACKS
HYDROGEN BONDS
THERMAL PROPERTIES OF WATER
• HIGH SPECIFIC HEAT CAPACITY
• SPECIFIC HEAT CAPACITY= AMOUNT OF HEAT ENERGY THAT MUST
BE ADDED TO A GIVEN MASS TO RAISE THE TEMPERATURE OF A
SUBSTANCE BY 1* C
• LARGE AMOUNT OF ENERGY REQUIRED TO RAISE TEMPERATURE
OF WATER
• SMALL AMOUNT NEEDED TO HEAT AIR
• LARGE BODIES OF WATER  SLOW TO CHANGE TEMPERATURE
AS ENVIRONMENT CHANGES
• STABLE HABITATS
• INSIDE OF ORGANISMS PRIMARILY COMPOSED OF WATER 
STABLE ENVIRONMENT STABLE BODY TEMPERATURE
• TEMPERATURE = KINETIC ENERGY
• HIGH TEMP = HIGH KINETIC ENERGY
• IN ORDER TO INCREASE TEMPERATURE OF EATER, HEAT MUST NOT
ONLY INCREASE THE KINETIC ENERGY OF THE WATER MOLECULES,
BUT ALSO BREAK HYDROGEN BONDS
THERMAL PROPERTIES OF WATER
• HIGH LATENT HEAT OF VAPOURISATION
• DEF: A MEASURE OF THE HEAT ENERGY NEEDED TO VAPORIZE A LIQUID
(CAUSE IT TO EVAPORATE)
• LIQUID TO GAS
• LIQUID WATER TO WATER VAPOUR
• BECAUSE OF HYDROGEN BOND, LARGE AMOUNTS OF ENERGY ARE NEEDED
FOR VAPORIZATION TO OCCUR (H-BONDS MUST BE BROKEN FOR WATER TO
ESCAPE AS A GAS)
• WATER HAS HIGH LATENT HEAT OF VAPORIZATION
• THIS LEADS TO HIGH HEAT CAPACITY
• DURING VAPOURIZATION:
• ENERGY IS TRANSFERRED TO WATER MOLECULES AS THEY BECOME A GAS
• THIS MEANS THAT LIQUID WATER REMAINING LOSES ENERGY FROM ITS
SURROUNDINGS = COOLING DOWN OF LIQUID WATER
• WHEN WATER EVAPORATES, IT ABSORBS LOTS OF ENERGY FORM
SURROUNDINGS
• EVAPORATION OF WATER HAS A COOLING EFFECT
• SWEAT
• PANTING
THERMAL PROPERTIES OF WATER
• HIGH LATENT HEAT OF VAPOURISATION
• FREEZING OF WATER IS THE OPPOSITE
OF VAPORIZATION
• WHEN GOING FROM LIQUID WATER TO
SOLID ICE, WATER MOLECULES MUST LOSE A
LARGE AMOUNT OF ENERGY
• WATER MOLECULES LITERALLY RELEASE
ENERGY WHEN THEY FREEZE….THIS
WARMS UP THEIR SURROUNDINGS…
• WATER UNDERNEATH A LAYER OF
ICE WARMS UP, PREVENTING A LAKE
FROM FREEZING STRAIGHT
THROUGH
THERMAL PROPERTIES OF WATER
• FREEZES FROM THE TOP DOWN
• LIQUID WATER BECOMES DENSE AS IT COOLS
• WATER MOLECULES LOSE KINETIC ENERGY AND MOVE
CLOSER TOGETHER
• AT 4*C, WATER IS LIQUID
• AT 0*C, WATER IS SOLID
• WATER MOLECULES FOR A LATTICE
• WIDELY SPACED WATER MOLECULES B/C HYDROGEN
BONDS ARE FIXED
• ICE IS LESS DENSE THEN WATER (IT FLOATS)
• LAYER OF ICE = INSULATOR
•
SLOWS DOWN THE LOSS OF HEAT FROM THE WATER
BENEATH IT
•
MARINE ORGANISM SURVIVE WINTER
• CHANGES IN DENSITY OF WATER  CURRENTS
• MAINTAIN CIRCULATION OF NUTRIENTS IN
BODIES OF WATER
COHESIVE AND ADHESIVE PROPERTIES
• ADHESION
• WATER STICKS TO OTHER MOLECULES
• WALLS OF XYLEM
• COHESION
• WATER STICKS TO WATER
• HIGH COHESION = HIGH SURFACE TENSION
• CAPILLARY ACTION= ADHESION +COHESION
WATER AS A REAGENT
• A REACTANT IN CHEMICAL REACTIONS
• EXAMPLES?
• PHOTOSYNTHESIS
• ENERGY FROM SUN IS USED TO SEPARATE THE HYDROGEN IONS
FROM THE OXYGEN IN THE WATER MOLECULE
• PHOTOLYSIS SUNLIGHT BREAKING UP WATER MOLECULES INTO
HYDROGEN IONS AND OXYGEN MOLECULE
• HYDROGEN IONS USED TO FUEL THE REST OF PHOTOSYNTHESIS
REACTIONS TO MAKE GLUCOSE (ELECTRONS ALSO RELEASED TO GO
DOWN ETC)
• OXYGEN MOLECULES ARE RELEASED INTO THE ATMOSPHERE AS A
WASTE PRODUCT BUT USED AS A REACTANT IN AEROBIC RESPIRATION
• HYDROLYSIS REACTIONS
• HYDRO= WATER
• LYSIS= TO BREAK DOWN
• WATER IS USED TO BREAK DOWN LARGER MOLECULES (LIKE
POLYSACCHARIDES, PROTEINS, FATS)
• COMMON IN DIGESTION
WATER MOLECULE ACTIVITY
• Your group needs to create at
least 15 water molecules
• GO TO TABLE WITH YOUR ASSIGNED
• White = hydrogen
NUMBER
• Red = oxygen
• SMART PHONE APP REQUIRED:
• Black Pipe cleaners =
FLIPAGRAM
covalent bond
• Colored yarn shows
• MATERIALS
hydrogen bonds
• WHITE PAPER
• Use dry erase boards to
• RED PAPER
label each stage
• BLACK PIPE CLEANERS
• Stages of Water to represent:
• COLORED YARN
• Liquid water
• SCISSORS
• Solid Water
• DRY ERASE BOARD AND MARKER
• Water Vapor
• SMART PHONE
• A lake covered with a
• BEIGE PAPER (BACKDROP)
layer of ice
PRACTICE TEST QUESTIONS
• WRITE OUT QUESTION AND DETERMINE CORRECT ANSWER
11.