1. C H E M I S T R Y

2. Levels of Organization
As things get more complex, things tend to get more disorganized
Natural events tend to increase disorder
Entropy- disorder
Living things are highly organized
They use energy to maintain their organization
Living things need a continuous input of energy
Atoms
Molecules
Organelles
Cells
Tissues
Organs
Organ Systems
Organisms
Unicellular
Multicellular

3. Elements
A substance that cannot be broken down into simpler chemical substance (90 natural elements)
Of all the elements, only about 25% are essential to living organisms
ALL LIVING THINGS CONTAIN CARBON!!
Each element is identified by a 1 or 2 letter symbol
H, He, Li, Mg

4. Atoms Elements are made up of atoms Structure Electron Energy Levels
The smallest particle of an element that has the characteristics of that element
Structure
Nucleus made up of protons (+) and neutrons (neutral)
Surrounding the nucleus are electrons (-)
Electron Energy Levels
The 1st level can hold up to 2 electrons, the 2nd level can hold up to 8 electrons
Atomic Number
The number of protons
Atomic weight
The weight of the nucleus (protons + neutrons)

6. Isotopes and Ions Isotope Ion
An atom of the same element that have different numbers of neutrons
Ex. Carbon-14- used for radioactive dating because isotopes are usually unstable and break apart easily to give off radiation
Radiation is also used in medical practices
Radioactive cobalt is used for cancer patients
Radioactive iodine is used for seeing the functioning of the thyroid gland
Ion
an atom that gains or loses an electron
either positively or negatively charged
ex. Na+, Cl-

8. Bonds Covalent bond- sharing of electrons
Ex. H2O, CH4, CO2
Most compounds in organisms have covalent bonds
Ionic bond- form through the loss or gain of electrons
Ex. NaCl- Na loses an electron, Cl gains one
Ionic bonds are not seen as frequently in living organisms, but are important in nerve impulses, muscle contractions, etc.

10. Why do atoms bond? They combine to become more stable
They do this by having their outermost energy level filled

11. What happens when atoms bond?
Molecule- a group of atoms held together by covalent bonds and having no overall charge
Ex. H2O
Compound- a substance that is composed of atoms of 2 or more different elements that are chemically combined
Ex. NaCl, CO2
Mixture- a combination of substances in which the individual components retain their own properties
Solution- a mixture in which 1 or more substance are distributed evenly in another substance

12. COHN The four most abundant elements in the body Carbon- 18.5%
Oxygen- 65%
Hydrogen- 9.5%
Nitrogen- 3.3%
Trace elements- very small amount of these elements in the body
We get them from food

13. Role of Carbon A carbon atom has 4 available electrons for bonding
Makes covalent bonds
When each atom shares 2 electrons, a double bond is formed
Ex. CO2

14. Role of Carbon, cont.
Carbon can form straight chains, branched chains, rings, etc.
Isomers- molecules with the same chemical formula but different structure
Diamonds and Graphite are completely made of carbon
Diamonds are the hardest substance on Earth
Graphite can be broken easily
They can do different things because their structures are so different
DNA backbone is partially made of carbon
Carbon Cycle- when organisms die, CO2 is emitted
Photosynthesis and Respiration

16. Without Carbon…
THERE WOULD BE NO LIFE!!!