why study chemistry in biology?. starch molecule glucose molecules
TRANSCRIPT
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
•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
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
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:
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?
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 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