Why Study Chemistry in Biology?

I. The Atom

A. Definition: smallest particle of an element

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

Location of Electrons

outermost electrons participate in BONDING

II. Elements

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)

Radioactive Isotopes

Bohr Atomic Model

•Atoms Space

DO NOW

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

A. Compound definition:

a substance containing two or more

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

III. Chemical Compounds

• Atoms want to fill their outer energy

levels to be

• To do this, they will meet up with other atoms and either or

electrons

i. Atoms share electrons

Examples of covalent molecules

ii. Ionic Bonds: gimme’ that electron!

• Atoms transfer electrons, becoming (+) or (-) charged

• The attraction brings them together– Ex: Na+ and Cl- = NaCl!

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. Molecules definition: two or more atoms held together by COVALENT bonds

LIFE DEPENDS ON THE UNIQUE PROPERITIES OF WATER

V. WATER

Questions to think about

• Why do put salt on the roads? • Why do we add salt to a pot of pasta

water? • At a higher altitude why must we

cook “boil” something longer?

A. Human Composition: Cells are 70–90% water

B. Plant Composition

As much as 95% plants can be made of water

C. Formula:H2O

D. Bonds: i. Hydrogen bonds: Hydrogens from one water molecule are ATTRACTED to the oxygen of ANOTHER water molecule: they develop a weak bond

i. Cohesion 1. Definition: Water “sticks” to each other Ex.: Surface tension

1-inchpaperclip

over-filled water

3oz Dixie cup

Jesus Christ Lizard

ii. Adhesion

1. Definition: Water molecules attracted to other molecules.

2. 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-)

iii. 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?

• 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

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

LOW DENSITY OF ICE• Density- amount of matter

in a volume

• In most substances the solid state is more dense than the liquid state

• Water is the opposite

ICE IS LESS DENSE THAN WATER and will FLOAT

LOW DENSITY OF ICE

• WHY?• Hydrogen

bonds in ice (solid) keep molecules spaced out

LOW DENSITY OF ICE

• Floats • Ice insulates the

liquid water below allowing life to persist