BIOL 1201 Lecture : BIOLOGY SUPER NOTES
Biology 1201 10/20/2014 3:35:00 PM
22/8/12
What is science?
What do scientists do?
-Make observations
-attempt to discern patterns
-assume that the future is in line with the past
Scientific method
1. Observation
2. Generalized model
3. Predictions or hypothesis
4. Test
Process yields better and better models
Does not ever include the “truth”
Hypothesis – Prediction not yet tested (Best guess)
Theory – Hypothesis that is tested many times and supported
Law – Theory that continues to be tested and is close to proven
What is Biology?
-The study of life
What is Life?
Characteristics
-Organization
-Energy use i.e. gas exchange, using resources
-Development i.e. Growth, changes
-Reproduction
-Evolution/ adaptation
-Response to the environment
• Basic check to see if something is alive
What Determines solubility?
• Like dissolves Like
Polar + Polar
Polar + nonpolar
Nonpolar + nonpolar
Cells are filled with water so solubility is very important with biology
What determines polarity?
Atom
• Smallest particle of an element separable by normal chemical
means
24/8/12
The number of electrons in an atom is irrelevant when talking about the
properties of that element. Electrons only determine charge
Valence
• Number of electrons an atom needs to gain or lose in order to have
a full outer shell
• Also predicts the number of bonds an atom will make
• Number of electrons in outer most shell
Electrons fill from the inside out
KLM shells in the Bohr model
LI K holds 2, L and M hold 8
3p Li has 1 valence electron
Atoms are lazy. They will often use the valence number that is lower
Phosphorus can have a valence of 3 or a valence of 5
What determines polarity of a molecule?
• The types of bonds within that molecule
Chemical bonds
• Form when atoms gain or lose electrons resulting from electrical
attraction
Ionic Bonds
• When electrons are totally lost or gained from one atom to the
other
• Strongest bond when dry
Covalent bonds
• Form when atoms share electrons
• If they equally share electrons = covalent non polar
• If they are shared unequally = polar covalent
• Strongest bond in water
Are ionic, covalent, and polar covalent bonds really that different?
• The are the same attraction just different in how they share
electrons
Covalent polar covalent Ionic
Equal sharing No sharing
What determines the number of bonds?
• Valence
What determines the type of bond?
• Electronegativity
o Measure of how much an atom wants an electron
Ionic
• When difference between electronegativity is greater than 1.7
Covalent
• When difference between electronegativity is below 0.5
Polar covalent
• When difference is between 0.5 and 1.7
0 - 0.5 = Covalent
0.5 - 1.7 Polar covalent
1.7 - > = Ionic
Any 2 atoms of the same element bonded together will be covalent because
the electronegativity will be the same and the difference will be zero
Bonds influence the polarity.
Molecules with ionic bonds will be polar and go into solution in water
Molecules with polar covalent bonds will also be polar
Molecules with pure covalent bonds will be non polar and not dissolve in
water
Weak bonds
Hydrogen bonds
Document Summary
Assume that the future is in line with the past. Scientific method: observation, generalized model, predictions or hypothesis, test. Hypothesis prediction not yet tested (best guess) Theory hypothesis that is tested many times and supported. Law theory that continues to be tested and is close to proven. Response to the environment: basic check to see if something is alive. Cells are filled with water so solubility is very important with biology. Atom: smallest particle of an element separable by normal chemical means. The number of electrons in an atom is irrelevant when talking about the properties of that element. Valence: number of electrons an atom needs to gain or lose in order to have a full outer shell, also predicts the number of bonds an atom will make, number of electrons in outer most shell. Li k holds 2, l and m hold 8. They will often use the valence number that is lower.
