1. Introduction to Chemistry
I thought we were in biology this year……

2. Bio and chem perfect together
The chemical basis of life leads us to an understanding of how things work in biology
So we need to know some basic chemistry first
Really this might be a review for everyone

3. Atoms and Compounds
Element is a substance that cannot be broken down any further
Periodic Law (you know the Table)
Smallest unit of an element is an atom
Atom comprised of nucleus and electrons
Nucleus comprised of protons and neutrons

4. Atoms and Compounds (2)
What makes one element different from another is the number of protons and electrons in each
92 elements occur in nature, 20 more made in a lab
Only 6 make up 99% of all living organisms (C, H, N, O, P, S)

5. Atoms and Compounds (3)
All the CHNOPS elements are small, light, form covalent bonds, electrons close to the nucleus, form bonds with two or more atoms (except H)
The links between atoms are called bonds
A substance formed by bonding of atoms is called a compound

6. Atoms and Compounds (4)
IMPORTANT: an atom is the smallest part of an element, a molecule is the smallest part of a compound
Two types of bonds important in biochemistry: Ionic and Covalent

7. Bonds (1) Ions Ionic bond
An atom that has gained or lost an electron and thus acquires a negative or positive chargIons
Ionic bond
The strong attraction beteween oppositely charged ions
Usually link atoms in small compound together
Stabilize macromolecules

8. Bonds (2) Covalent bonds; electrons are shared between two atoms
A group of atoms linked by covalent bonds behaves as one unit. This is called a molecule
IMPORTANT: an atom is the smallest part of an element, a molecule is the smallest part of a compound

9. Chemical Formulae
Shorthand used by scientists to write the names of elements and compounds
Some examples on periodic table

10. Water (1) H2O Electrically neutral but does not behave that way
Has a slight negative charge at one end, slight positive charge at the other end; this is called polarity
Water dissolves substances, the resulting liquid is called a solution; biochemistry is solution chemistry, everything happens in solution

11. Water (2) Water can dissociate (come apart) into ions H+ and OH–
H+ and OH– are two of the most reactive ions in nature
A compound that produces H ions is called an acid
A compound that produces OH ions is called a base

12. Water (3)
The acidity and basicity of a solution is important in biochemistry
We measure the acidity/basicity of a solution by measuring the concentration of H ions in it.
The concentration scale is called the pH scale. Values of pH 1-7 are acids, 7-14 are bases

13. More on Water (1) On earth water is a common liquid
¾ of earths surface is covered in water
50-90% of the weight of a living system is water
Common is not the same as ordinary
Water is an extraordinary liquid for many reasons

14. More on Water (2) Water and the Hydrogen Bond
Polar molecule
Electrically asymmetrical
Opposite charges lead to hydrogen bonding
Every water molecule can form a hydrogen bond with four other water molecules
A single H bond is very weak, all together however H bonds are very strong

15. More on Water (3) Water and the Hydrogen Bond
H bonding gives water surface tension
The only liquid with a greater surface tension that water is mercury
Water has cohesive and adhesive properties (cohesion holding together like substances, adhesion holding together unlike substances)
Mercury is only cohesive

16. More on Water (4) Water and the Hydrogen Bond
Cohesive and adhesive properties lead to water having capillary action and imbibition
Capillary action is the ability of water to move upwards or downwards in small spaces, imbibition is ability of water to move inside unlike substance like wood

17. More on Water (5) Water and Temperature
Water has a high specific heat (heat capacity)
Due to H-bonding
Energy of movement (kinetic energy) is first used to break H bonds, then temperature can increase
Heat and temperature are not the same!!
TEMP: measured in degrees, represents average kinetic energy
HEAT: measured in calories, represents number and mass of molecules present

18. Yep More on Water (6)
Water has a high heat of vaporization (evaporation)
Due to H bonding again
Takes 540 calories to change 1 g water to vapor
Consequence is that evaporation of a water molecule carries a lot of heat with it
Evaporation has a cooling effect; organisms can unload excess heat by evaporation of water

19. Water (7)
The freezing point of water is also the melting point (at 0 degrees C) (heat of fusion)
Ice and snow are temperature syabilizers
Water maximum density is at 4 degrees
Solid water takes up more volume than liquid
Solid water forms on the top of a pond
Insulates the water underneath at close to 0 degrees

20. Water (8) The solvent
Hydrophilic compounds dissolve in water to make solutions
Hydrophobic compounds do not dissolve in water
H bonding forces hydrophobic compounds to self associate
Very important for biological structures