Transcript Water Frayer Packet

Water Frayer Packet
Water
• Structure
– H2O – water has a bent “V” shape because oxygen pulls
electrons more strongly than each hydrogen
• Define Polar Molecule
– Molecule with opposite charges at either end because of an
unequal sharing of electrons
• Type of Bond
– Each water molecule is formed by covalent bonds
– Hydrogen bonds hold water molecules together
• Why does oxygen pull electrons more strongly
than hydrogen?
– Oxygen has 8 protons and each hydrogen only has 1
– Remember that opposite charges attract, so protons like to
be near electrons
Bonds In and Between Water
Molecules
Covalent
Bonds
• Definition
Density
– The amount of matter in a given volume
• Example
– Ice floats because its molecules are less densely packed
than those in liquid water.
• Properties
– Solid water is LESS dense than liquid water
– Due to hydrogen bonding
• Role in Living System
– If ice sank, bodies of water (ponds, lakes etc.) would freeze
from the bottom up and organisms would not have access to
nutrients on the muddy bottom. Instead, ice floats and
creates an insulated barrier for life below.
Which is less densely packed?
Cohesion
• Definition
– Molecules of the same kind sticking together
• Example
– Water sticking to other water molecules
• Properties
– Cohesion is stronger for water than most other
liquids
– Surface tension (caused by cohesion & hydrogen
bonding) allows water striders to walk on water
• Role in Living Systems
– Needed to helps plants transport water from their
roots to their leaves
Adhesion
• Definition
– Attraction between unlike molecules (different kinds of
molecules)
• Example
– Water sticking to a glass or leaf
• Properties
– Water can stick to other surfaces
• Role in Living Systems
– Needed to helps plants transport water from their roots to
their leaves
– In plants, adhesion between water molecules and the tiny
“tubes” inside plants helps keep water from moving
downward with the force of gravity
Cohesion and Adhesion needed for
Plants
• Definition
pH
– Measure of how many hydrogen ions (H+) are in a solution
• Example
– Acids donate H+ to a solution (ex. Stomach acid)
– Bases remove H+ from a solution (cleaners)
• Properties
– Each pH unit is a tenfold change in the concentration of H+
ions
– pH of 7 has equal H+ and OH- concentrations
• Role in Living Systems
– pH of the solution in most living cells is close to 7
– Maintaining the correct pH inside cells is critical to life;
buffers help to do this by removing and donating H+ to
maintain homeostasis
pH scale
Solvent
• Definition
– Substance that dissolves other substances
• Example
– Sugar water : sugar is solute and water is the
solvent
• Properties
– Water is the universal solvent
• Role in Living Systems
– Water is the main solvent inside all cells, blood,
and in plant sap
– Helps with chemical reactions in living organisms