Biology 12 Name: _________________________________ Block: _________ Date: _______________
Unit 1 – Homeostasis; Chapter 2 – The Molecules of Cells
2.1 – Basic Chemistry AND 2.2 Molecules and Compounds (p24-29) – STUDENT NOTES
Why study Chemistry in Biology Class?
All life is made up of ____________
Matter is anything that _______________________________________________
All matter ( ________________________________) is made up of _______________________________
Definitions:
Element =
Atom =
Ion =
o Cation
o Anion
Chemical Bonds:
Atoms of a molecule are held together by ____________________________________
The likelihood than an atom will form a chemical bond with another atom depends on ____________________
__________________________________________________________________, also called the valence shell.
Stability (and full valence shells) is the goal.
Stability is obtained by _____________________________ or ________________ electrons.
Three Types of Chemical Bonds
1) _________________ Bonds Formed between ____________________
and _________________ atoms.
An ionic bond is a ___________________ of electrons from
_____________( _____________ ion) to
a __________________ (_______________ ion)
2) ________________ Bonds
Formed between ____________________ and _________________ atoms.
Atoms of molecules ___________________ pairs of their valence electrons.
i. _____________ _____________ bond = sharing one pair of electrons
ii. _____________ _____________ bond = sharing two pair of electrons
iii. _____________ _____________ bond = sharing three pair of electrons
There are 2 types of Covalent Bonds:
a) __________________ covalent bonds
= share electrons _______________.
One atom doesn’t attract the shared electrons more
Than the other atom.
b) __________________ covalent bonds
= ___________ sharing of electrons between atoms
In a water molecule, oxygen has the greater
Electronegativity and attracts the H electrons
More strongly.
A comparison: covalent vs. ionic bonding
3) Third type of Chemical Bond = ____________________ Bonds
H is covalently bonded with one atom to form a molecule (e.g H2O, NH3)
Then the H in the covalently bonded molecule is attracted to another atom (usually O, N or F) of a
different molecule
H bonds form weak intermolecular bonds; and serve as links between molecules.
i. For example H-bonds between water molecules, DNA nitrogenous bases, proteins.
H bonds help determine the three-dimensional shape of molecules
H bonds are ALWAYS represented by dotted lines
Examples shown below – water and DNA molecule
If you need more Chemistry review … check out:• www.KhanAcademy.org the Chemistry section• https:// cnx.org/contents/[email protected]:xVWiZWMF@10/Atoms-Isotopes-Ions-and-Molecules-The-
Building-Blocks Open Stax, Biology 2e, Chapter 2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks
• YouTube – Discover Science Now - Bio12 – Biochem Playlist, videos # 1, 3, and 4
Now we can finish these definitions ...
Molecules =
Compounds =