Why Study Chemistry in Biology?

STARCH MOLECULE

GLUCOSE MOLECULES

You can prolong life by keeping bananas in cooler temperatures.

I. Atoms

A. Definition: smallest part of matter: living and non-living

B. Composition

Subatomic Particle

Charge Mass Location

Proton +1 1 Nucleus

Neutron 0 1 Nucleus

Electron -1 1/1840 the mass of a

proton

Orbiting nucleus

Bohr Atomic Model

Location of Electrons

outermost electrons participate in BONDING

•Atoms Space

•Why if atoms have so much space can we be solid?

II. Elements

Atomic Mass 12.0107 amu

Mass Number

A. Definition: substance that cannot be broken down into other substances

B. Biologically important elements i. Major: C H O N P S Carbon Hydrogen Oxygen Nitrogen Phosphorus Sulfur

ii. Minor: Calcium Potassium Iodine Chlorine Magnesium

Radioactive Isotopes

Counting Atoms

C6H12O6

So in this molecule, there are 6 carbon atoms, 12 hydrogen, and 6 oxygen

Element subscript is the NUMBER of ATOMS

A. Compound definition:

a substance containing two or more

elements in a fixed ratio– Ex: H2O, NaCl, CO2

III. Chemical Compounds

i. Covalent Bonds:

• Electrons are shared to create a strong bond

Cl2

B. Bonds:

ii. Ionic Bonds

• Transfer of electrons between atoms to create a bond

• Ion- an electrically charged atom

• Gain electron; negative charge

• Lose electron; positive charge

LOSER GAINER

JOKE- Don’t Have to write this.• A NEUTRON walks into a diner and sits down to

order a meal.

• When the waitress brings the food over the neutron says “Can you bring the check? I am in a hurry!”

• The waitress replies, “Don’t worry

about it, there is NO CHARGE

for you.”

JOKE- Don’t have to write this.

• Two atoms walk down the street and collide.

• One atom says to the other, “Are you okay?”

• The second atom replies, “I think I lost an electron.”

• The first atom says, “Are you sure?”

• The second one says, “Yeah, I’m POSITIVE!”

iii. Extras

• Two or more atoms held together by covalent bonds

• Can have different properties when together then when apart

1. Molecule definition:

LIFE DEPENDS ON THE UNIQUE PROPERITIES OF WATER

Questions to think about

• Why do put salt on the roads? • Why do we salt a pot of pasta water? • At a higher altitude why must we

cook “boil” something longer?

• Cells are 70 to 95% water

Human Composition

Hydrogen Bond

• Weak attraction between a slightly positive and a slightly negative

Plant Composition

• As much as 95% plants can be made of water

Formula and Bonds

Formula: H2O

Bonds: Covalent- electrons are shared between Oxygen and Hydrogen

Because Oxygen has 8 Protons (+) it pulls the electrons more (Electron HOG)

Oxygen acts Negative- Hydrogen acts Positive

HH

O

How do we get Hydrogen Bonds?

Hydrogen Bonds

• Hydrogen Bonds- weak bondsslightly positive H is attracted to the slightly negative O of another water molecule

Polarity • Polar molecule:

molecule in which opposite ends have opposite electric charges

• Why? Water is a polar molecule: because Oxygen is an electron HOG

The polar nature of water and the effects of hydrogen bonding explain most of water's unique properties.

• Cohesion • Adhesion• Solubility • Temperature moderation• The lower density of ice

Cohesion • Water “sticks” to each other

• Surface tension= when cohesion pulls water molecules at the surface tightly together, forming a film-like boundary

1-inchpapercli

pover-filled water

3oz Dixie cup

Jesus Christ Lizard

Adhesion

• Water molecules are also attracted to certain other molecules.

• Ex. In trees/plants water goes against gravity

Called capillary action

Water is the a Universal Solvent

Water is able to dissolve other Polar & ionic compounds when mixed by causing the ions to break away and surround them.• Water dissolves Salt (Na+Cl-)

Temperature and Water

• When you heat molecules move faster

• When you cool molecules move slower

• Water takes more energy to heat because energy must break hydrogen bonds

Boiling Point: 100 oC 212 oF

Does water boil faster if you add salt to it?

• Yes or No- pollseverywhere • Water Boils when it has enough energy for the

molecules to leave

Freezing Point

• What would happen if our oceans did not have salt in them?

• Why do we put salt on our roads?

• Why at effect does salt have on FREEZING POINT?

0 oC or 32 oF

Homework Questions 1. Explain how the structure of water molecules results in attractions among them.2. Give an example of how cohesion among water molecules is important to living things.4. Name three conditions on Earth that make the planet suitable for life.5. Explain one way in which water can moderate temperature.

Why is this important for life?

Water Boiling Point Ethanol Boiling Point

• Why are higher altitude must we cook “boil” something longer?

•Why do we need salt in our ice, when making ice cream? Watch Video

• http://www.youtube.com/watch?v=0eNSnj4ZfZ8

• Review of Water Properties for Lab