O

-

-

-

-

-

-

-

-

H-

H-

Water (H2O)

Water is a polar moleculeThis means that . . .

A. All atoms have equal electrical chargesB. A water molecule is linear, like a poleC. The opposite ends of the molecule have

opposite electrical chargesD. Water is hydrophobic

Water is a polar molecule

O

-

-

-

-

-

-

-

-

H

-

H-

Water (H2O)

Non-polar: electrons are shared equally among atoms

Polar: electrons are NOT shared equally among atoms

• Hydrogen bond – a WEAK bond that forms between a Hydrogen atom in one molecule and an atom in another molecule

Web animation

• Polar molecules dissolve in water• Hydrophilic = water loving

• Ion – an atom that has gained or lost an electron

17 e -11 e -

• Ion – an atom that has gained or lost an electron• Ionic bond – attraction between two oppositely

charged ions

Water and sugar demo

Sugar (glucose) dissolves in water because it is . . .

A. an ionic compound.

B. a polar molecule and forms many hydrogen bonds with water molecules.

C. a very unstable molecule.

D. highly non-polar.

Glucose

C6H12O6

-

Types of Chemical Bonds

• Covalent bond = atoms share electrons

VERY STRONG

• Ionic bond = (+) atoms attracted to (-) atoms

WEAKER

• Hydrogen bond = Partial (+) attracted to Partial (–)

WEAKEST

pg. 42

What type of bond is indicated by the arrow?

A. Hydrogen bond B. Covalent bondC. Ionic bondD. Hydrophobic bond

Covalent bond

Properties of water1. Cohesion – water molecules stick together

Properties of water1. Cohesion – water molecules stick together

2. Large heat capacity

Properties of water1. Cohesion – water molecules stick together

2. Large heat capacity

3. Low density as a solid

Properties of water1. Cohesion – water molecules stick together

2. Large heat capacity

3. Low density as a solid

4. Good solvent

Human circulatory system displayed at the Bodies exhibit

Water has so many unique properties because . . . .

A. of the covalent bonds between the oxygen and hydrogen.

B. of its ability to hydrogen bond.C. of its ability to make and break

ionic bonds. D. the electrons are shared equally

between the oxygen and hydrogen atoms.

• The abundance of water is a major reason why there is life on Earth

WATER FOR LIFE

Water!!!

• Water is a polar molecule that easily forms hydrogen bonds.

• Because of this, it has four characteristics that has allowed life exist on Earth

Water’s Life Supporting Properties

Cohesion: • Water’s polarity causes it to form Hydrogen

bonds with itself, so the molecules stick together– Called Cohesion

• This allows water to travel up tree roots into trees, and gives water surface tension, which allows things to “stand” on top of water

Water’s Life Supporting Properties

Water’s High Specific Heat: • Specific Heat: The amount of energy needed to

raise 1 gram of a substance 1 degree Celcius• Water has a very high specific heat!!!• This is because its hydrogen bonds absorb lots of

heat• Water covering the Earth regulates the Earth’s

temperature, keeping in the liveable range

Water’s Life Supporting Properties

• Ice is Less Dense than Water: • When water freezes, it forms a

lattice that makes it less dense than water– Less molecules in the same volume– Most solids are denser than liquids

• THIS MAKES ICE FLOAT!!!• Ice floating allows only the tops of

water bodies to freeze, thus not killing all life

Hydrogen bond

Ice

Hydrogen bonds are stable

Liquid water

Hydrogen bondsconstantly break and re-form

Hydrogen bond

Ice

Hydrogen bonds are stable

Liquid water

Hydrogen bondsconstantly break and re-form

ICE

Because only the top

freezes, the living things

underneath don’t freeze to

death

Water’s Life Supporting Properties

Water is the Universal Solvent: • Solution: A homogenous mixture of two or more

substances– Solvent: Dissolving agent, Solute: What is dissolved– Aqueous Solution: A solution where water is the solvent

• Because water is polar, atom with a charge or ionically bonded compound will dissolve in it

• This allows all living things (which are water based), to dissolve the variety of compounds they need for life– Example: Cells, blood, tree sap, etc…

Ion insolution

Saltcrystal

Bellringer

• What are the 2 types of bonds?

• Draw me the Lewis Dot structure of 2 hydrogen atoms

Agenda

• Objective: To begin bonding practice• Agenda:

– Bellringer/Discussion– Grade Atom WS– Practice Bonding– Go over rubric for tomorrow

• Homework: – Bonding write-up due Tuesday

Molecule Models

• Every group needs one bag of model materials– The circles with pegs are atoms– The bendy plastic pieces are bonds

• Each peg represents a bond that atom can make• Based on what you know about the number of

valence electrons each atom has, tell me which atoms you have are Hydrogen, Oxygen, and Carbon

• Everyone must write this on their own sheet

Molecule Models

Make Models of the following Molecules:

• H2, O2, H2O, CO2, CH4, C2O2, C2OH2, C6H12O6

On your sheet, you must draw the following:

• Lewis Dot Structures of each atom pre-bonding

• Line/Lewis Dot Structures post-bonding

• Label single/double bonds

• COPY THIS EXAMPLE DOWN!!!

Molecule Models

Make Models of the following Molecules:

• H2, O2, H2O, CO2, CH4, C2O2

On your sheet, you must draw the following:

• Lewis Dot Structures of each atom pre-bonding

• Line/Lewis Dot Structures post-bonding

• Label single/double bonds

• COPY THIS EXAMPLE DOWN!!!

Bellringer

• Study

• Get out whatever periodic table you are going to use during the quiz

Bellringer

• Name and describe 2 of water’s 4 unique properties that allow life to exist and flourish on Earth

• Do you like drinking water?

Agenda

• Objective: To start the water mini-lab• Agenda:

– Bellringer/Discussion– Go over quiz stuff– Go over lab– Lab all period

• Homework: – Quiz tomorrow– Lab due Monday– Macromolecule Chart due Monday

Quiz

• Atomic Info

• Bohr Models

• Lewis Dot Structures

• Bonding like in the bonding WS

Water Mini-Lab Write Up

• You are going to perform the following tests on water and vinegar

1. How many drops of water/vinegar will fit on top of a penny?

2. Is there cohesion leading to surface tension?(will a staple rest on top of it)

3. Will Kool-Aid dissolve in it (make sure you use same mass/volume of liquid in each)

4. Is there cohesion-travel up thin tubes (celery)?

Water Mini-Lab Write Up

• Make a hypothesis for each test first• Make sure you control/record all amounts• RECORD ALL PROCEDURE/MATERIALS!!!• RECORD ALL DATA FOR GROUP!!!• HOMEWORK:

– Typed hypothesis, procedure, materials, and data, and conclusion due Tuesday

– Should be between 1-3 pages– Conclusion should just be an explanation of whether your

hypothesis was supported or not, and why based on data– 1 per group