Thank God We are Worth More than the Sum of our Parts!!

Insufficient Iodine and Goiters

Maybe We Should Call it "Almost"

ATOMS: Organized Collection of Protons, Neutrons, and Electrons

Helium

Carbon

Naturally Occurring Isotopes

Radioactive Isotopes

3rd Shell

2nd Shell

1st Shell

Why Electrons "Matter"

Van der Waal's Forces: Why Geckos Can Run Up the Wall

The Wonders of Water

Why water?

Water provides an environment in which many biological reactions take place.

Water is involved in and is a common product of many biological reactions.

O

O

Water is PolarH2O

Water is held together by covalent bonds, but oxygen keeps the electrons around it more than the hydrogens do. The result...oxygen has a slight negative charge while hydrogen has a slight positive charge.

OHH

- -

++

Water is polar. Show how polarity leads to hydrogen bonding between 8 different water molecules.

Water molecule

Hydrogen bond

OH

H

--+

+

OH H

--

+ +

OH

H

-- +

+O

HH

- -

++

OH

H

-- +

+

OH H

--

+ +

OH H

--

+ +

OH

H

--+

+

OH

H

-- +

+

OH

H

-- +

+

Liquid Water

Ice

Ice is less dense than water

Ice floats and insulates underlying water

High surface tension

Water drops form on surfaces

Strong cohesive properties

Water does not pull apart easily

Universal solvent

Medium for most biological reactions

Thermal properties

Much energy is necessary to change temperatures in large bodies of water.

Properties of Water

Capillary Action

Cohesion and adhesion allow water to move against gravity in plants/trees.

Hydrogen bonds

Individually, relatively weak; collectively very strong.

Polarity Allows for the formation of hydrogen bonds between other water molecules as well as different molecules.

wa

1 Cells are made of 70-95% water. In addition, cells are surrounded by water. As a result _____.

A the temperature of living things changes relatively slowly

B a variety of nutrients are available as dissolved solutes

C waste products can be easily removed

D dissolved substances can be easily transported within cells or between cells in multicellular organisms

E all of the above

2 Water is polar. This means that _____.

A the opposite ends of the water molecule have opposite electrical charges

B water molecules are linear.

C water is just one of the many hydrophobic molecules

D all of the atoms in a water molecule have equal electronegativities

E all of the above

3 The partial positive and partial negative charges on a water molecule occur because of _____.

A the unequal sharing of electrons between the oxygen and the hydrogen atoms in a water molecule

B the stability of one atom of a bond but not the other atom

C covalent bonding

D ionic bonding

E hydrogen's high electronegativity

4 In a drop of water molecules, hydrogen bonds form between _____.

A two oxygen atoms in different water molecules

B the hydrogen atoms in two different water molecules

C the hydrogen atom in one water molecule and a oxygen atom in another water molecule

D the hydrogens in a single water molecule

E none of the above

5 You fill a glass of water to just slightly above the rim without it spilling over the glass. What property of water best explains this?

A surface tension

B adhesion

C its thermal properties

D ice is less dense than water

E none of the above

6 Because molecules of water are farther apart in ice than in liquid form, _____.

A ice floats

B ice is denser than liquid water

C ice expands when it melts

D ice vaporizes before liquid water does

E all of the above

7 Nonpolar molecules that do not interact with water molecules are called _____.

A covalent

B hydrophillic

C hydrophobic

D none of the above