1. AP Biology Chemistry Notes
Name: ___________________
As we work through the notes make sure you’re filling in the blanks and highlighting key terms. Jot any extra notes along the side.

2. The Chemistry of Life

3. Why are we studying chemistry?
Chemistry is the foundation of Biology

4. Matter
Is defined as anything that _______________ ____________________________________. It makes up all the things you see around you and the gases you don’t
Matter is made of elements (______________ _____________________________________)
Compounds are a substance consisting of _______________ elements bonded together.

5. The World of Elements, but we’ll focus on these essential elements:Na Mg P S K Ca
About 25 elements are essential for life
Four elements make up 96% of living matter:
• carbon (C) • hydrogen (H)
• oxygen (O) • nitrogen (N)
Six elements make up most of remaining 4%:
• phosphorus (P) • calcium (Ca)
• sulfur (S) • potassium (K)
• magnesium (Mg) • sodium (Na)

6. Subatomic Particles:
Protons: are located in the _______ and have a _____ charge and weigh 1 atomic mass unit (amu)
Electrons: are located in the _______ and have a _____ charge
Neutrons: are located in the _______ and have a _____ charge and weigh 1 amu

7. Isotopes Atomic Number: ___________________
Mass Number:_____________________
Isotopes of an element has the same atomic number (protons) but different masses because of extra neutrons

8. Isotopes in Biology
Low levels of radiation such as radioactive iodine or glucose allow researchers to trace the location and activity of the atom in living tissues; therefore these isotopes are called tracers (________________________)
High levels of radiation can cause __________ ________________; careful use of radiation in turn can sterilize products and kill cancer cells.

9. Electrons and Energy
Electrons occupy an orbital at some level near or distant from the nucleus of the atom.
An orbital is a volume off space where an electron is most likely to be found; an orbital contains no more than _________________.
The more distant the orbital, the more _____________ it takes to stay in the orbital.

10. Electrons and Energy
When atoms absorb energy during ____________________, electrons are boosted to higher energy levels.
The innermost shell of an atom is complete with_____electrons; all other shells are complete with ______ electrons.

11. Elements & their valence shells
Elements in the same column have the same # of valence electrons & similar chemical properties
Remember
some food chains are built on reducing O to H2O
& some on
reducing S to H2S
ELECTRONEGATIVITY
Oxygen has medium electronegativity so doesn’t pull electrons all the way off hydrogen whereas chlorine would.
So oxygen forms a polar covalent bond.
Carbon has only a weak electronegativity so forms a nonpolar covalent bond

12. Chemical reactivity Atoms tend to
_______________________________________ or
This tendency drives chemical reactions…
and creates bonds
Ionic or Covalent bonds – –

13. Bonds in Biology Hydrogen bond Covalent bond – H2O H2O
H2 (hydrogen gas)

14. Nonpolar covalent bond
_____________________________________
Strong stable bond
example: hydrocarbons = CxHx
methane (CH4 )
Lots of energy stored… & released
Pair of electrons shared equally by 2 atoms
strong stable bond
example: hydrocarbons = CxHx
methane (CH4 )
balanced, stable, good building block

15. Polar covalent bonds ________________________________________________
Strong but ________________
Ex:_______________________
oxygen has stronger “attraction” for the electrons than hydrogen
oxygen has higher electronegativity
water is a polar molecule
+ vs – poles
leads to many interesting properties of water… H
Oxygen + – –
Pair of electrons shared unequally by 2 atoms
strong but interactive bond
example: bonds within water = H2O
oxygen has stronger “attraction” for the electrons than hydrogen
oxygen has higher electronegativity
water is a polar molecule
+ vs – poles
leads to many interesting properties of water… – – +

16. Hydrogen bonding Polar water creates molecular attractions
____________________________________________________________________________________________________
also can occur wherever an -OH exists in a larger molecule
Weak bond but common in biology
They help maintain complex molecule’s structure
H bonds H O
APBio/TOPICS/Biochemistry/MoviesAP/03_02WaterStructure_A.swf
attraction between H+ in one molecule to O- in another molecule
weak bond
example: bonds between water molecules
leads to many interesting properties of water

17. Ionic Bonds . Forms ________________ _______________________
These bonds fill the outer
shell making them
more stable ions
The attraction of oppositely
charged ions holds the 2
atoms together.