1. Chapter 2
The Chemistry of Life

2. The Nature of Matter

3. What is an atom?
The smallest particle of an element that has the chemical properties of the element.

4. Equal mass; Found in the Nucleus
The Atom
Three subatomic particles:
Protons: + charge
Neutrons: no charge
Electrons: - charge; in constant movement around the Nucleus
# protons = # electrons, so the atom is neutral overall.
Amazing Atoms
Equal mass; Found in the Nucleus

5. Elements A pure substance that consists entirely of one type of atom.
Listed on the periodic table.
Ex: hydrogen (H)

6. Isotopes
Contain same number of protons & electrons (so are the same element), but have a differing number of neutrons.
Ex: carbon-12 & carbon-14

7. Compounds Two or more elements chemically combined together.
The chemical and physical properties of a compound are different than the properties of the individual elements from which it is formed.
Ex: NaCl

8. Chemical Bonds Two types:
Ionic: Electrons are transferred from one atom to another; creates ions
Ions: charged atoms
Ex: Na+, Cl-
Covalent: Electrons are
shared (travel around
both nuclei); creates
molecules
Molecules: smallest unit of a compound with covalent bonds
Ex: H2O (2 atoms of H, 1 atom of O)

9. Properties of Water
A Good Review

10. Mixture Composed of two or more elements or compounds.
NOT chemically combined.
Solution: a mixture with components evenly distributed throughout
Two parts:
Solute: the part that is dissolved
Solvent: the part that is dissolving

11. Acids & Bases Acids: form H+ ions in a solution pH = 1-7
Bases: form OH- in a solution
pH = 7-14
Buffers: weak acids or bases that react with strong acids or bases to prevent sudden changes in pH
Help maintain homeostasis!

12. Carbon Compounds

13. Why is carbon in all life?
Carbon has 4 electrons for bonding, so it can form strong covalent bonds with many other elements (like H, O, P, S, and N).
Carbon can form single, double and triple bonds with itself.
Organic = contains Carbon

14. Macromolecules = giant molecules
Monomers: smaller unit
Polymers: larger compound
Types of Macromolecules: carbohydrates, lipids, nucleic acids, proteins

15. Function in Living Things
Carbohydrates
Chemical Composition
Examples
Function in Living Things
C, H, O
monosaccharides: simple sugars
( glucose, fructose, galactose)
polysaccharides: complex sugars (glycogen, starch)
Main source of energy.
Structural purposes in some cells (cellulose in plants).

16. Function in Living Things
Lipids
Chemical Composition
Examples
Function in Living Things
C, H, O
Glycerol + fatty acid
fats, oil, waxes
saturated: all single bonds (animal fats = bad!)
unsaturated: at least one double bond (vegetable fats = good!)
Stored energy.
Membranes & waterproof coverings.
Chemical messengers (steroids).

17. Function in Living Things
Nucleic Acids
Chemical Composition
Examples
Function in Living Things
C, H, O, N, P
sugar + phosphate group (P) + nitrogenous base (N)
polymers of nucleotides
DNA, RNA
Store & transmit genetic information.

18. Function in Living Things
Proteins
Chemical Composition
Examples
Function in Living Things
C, H, O, N, S
polymers of amino acids
enzymes
Control reactions (enzymes) & cell processes.
Transport materials in & out of cells.
Fight disease (antibodies).

19. Chemical Reactions & Enzymes

20. Chemical Reactions
When one set of chemicals changes into another set of chemicals.
CO2 + H2O  H2CO3
Chemical reactions always involve the breaking of bonds in the reactants and the formation of new bond in the products.

21. Chemical Reactions CO2 + H2O  H2CO3
Reactants: elements or compounds that enter into a reaction
Ex: CO2 & H2O
Products: elements or compounds that are produced by a reaction
Ex: H2CO3

22. Atoms and Chemical Reactions
2HCl + 2Na -> 2NaCl + H2
Remember the 2 after H2, means that there are 2 atoms of H in this molecule. (For H2O, there are 2 atoms of H and 1 atom of O.)
The 2 in front of 2HCl, means that there is 2 of the entire molecule, so 2 atoms of H and 2 atoms of Cl.

23. Energy in Reactions
Reactions that release energy often occur spontaneously.
Reactions that absorb energy will not occur without a source of energy.
Activation Energy: the energy needed to get a reaction started

24. Enzymes
Catalyst: a substance that speeds up the rate of a chemical reaction by lowering the activation energy.
Enzymes: proteins that act as catalysts in cells.
Substrates: the reactants of an enzyme-catalyzed reaction
Active site: spot on the enzyme where the substrate binds

25. How an Enzyme Works? (lock- and-key model)
Temperature, pH and regulatory molecules can affect the activity of enzymes.
Video

26. Two Special Types of Reactions
Dehydration synthesis: two molecules bond together & H2O is made
Used to make polysaccharides, lipids
& proteins
Hydrolysis: H2O is used to split two molecules