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 ChargeMassLocation Proton+11Nucleus Neutron01Nucleus Electron1/1840 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? Why if atoms have so much space can we be solid?

II. Elements Atomic Mass 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 C 6 H 12 O 6 So in this molecule, there are 6 carbon atoms, 12 hydrogen, and 6 oxygen Elementsubscript is the NUMBER of ATOMS

A. Compound definition: a substance containing two or more elements in a fixed ratio –Ex: H 2 O, NaCl, CO 2 III. Chemical Compounds

i. Covalent Bonds: Electrons are shared to create a strong bond Cl 2 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: H 2 O 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 bonds slightly 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-inch papercli p over-filled water 3oz Dixie cup

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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 o C 212 o F

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 o C or 32 o F

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

fZ8 fZ8 Review of Water Properties for Lab