Living and nonliving things are all made of elements. It is the way that atoms combine that give every element a different characteristic. Of the naturally occurring elements on earth, only 25 are essential to living organisms.

The elements Sulfur, Phosphorus, Oxygen, Nitrogen, Carbon, and Hydrogen (SPONCH) are the main components of living matter. Atoms are the building blocks of every element and all matter..

ATOMIC STRUCTURE The center of an atom is called the nucleus. Inside the nucleus are positively charged particles called protons. There are also particles with no charge, called neutrons. Outside the nucleus are negatively charged particles called electrons.

ISOTOPES Atoms of the same element can have different numbers of neutrons. These atoms are called isotopes. Isotopes are useful to scientists because they break down & their radiation is detectable, and can be used as a diagnostic tools. Ex. Iodine. Each atom has equal number of protons & electrons. No net charge.

COMPOUNDS AND BONDING A compound is a substance composed of 2 or more different elements combined. When elements combine they do so to gain stability. They can share electrons with another element or compound and give away electrons

Covalent Bonds When 2 atoms share electrons. Most compounds in organisms covalent bonds. A molecule is a group of atoms held together by covalent bonds. Ex. H 2 O ** The electrons travel in the orbitals of both atoms involved.

Ionic Bonds When atoms gain or lose electrons it becomes an ion. The attractive force between 2 ions of opposite charge is called an ionic bond. Ex. NaCl: Sodium Chloride

Van der waals forces Some atoms have a stronger attraction for electrons that others. This means a higher electronegativity. Even when sharing is equal, the movement of electrons can create forces of slight positive or negative charges.

When molecules are close together, a slight attraction can develop between oppositely charged regions of nearby molecules. These attractions are called Van der waals forces. They are not as strong as ionic or covalent bonds but can hold molecules together

CHEMICAL COMPOUNDS OF LIFE 1 Inorganic compound & 4 Major organic compounds found in living things

WATER MOST IMPORTANT OF ALL INORGANIC COMPOUNDS 2 Hs & 1O PROPERTIES: COHESION ADHESION CAPILLARY ACTION

Cohesion- An attraction between water molecules. Adhesion- An attraction between water and a different substance. Capillary action is an adhesion between water and tubes. (ex. Roots in plants) Polarity- The oxygen end of a water molecule is slightly negative because O has stronger attraction for electrons.

FYI: WATER facts RESISTS TEMPERATURE CHANGES EXPANDS WHEN IT FREEZES HELD TOGETHER BY H BONDS A molecule that has unequally distributed charges is called a polar molecule. Therefore water is considered polar covalent.

DEHYDRATION SYNTHESIS VS. HYDROLYSIS WATER IS REMOVED WHEN SYNTHESIZING (BUILDING) A MOLECULE WATER IS ADDED TO HYDROLYZE (BREAK DOWN) A MOLECULE

Solutions and Suspensions A mixture is a material composed of 2 or more elements or compounds that are physically mixed together but not chemically combined. A type of mixture is a solution. In solutions, all the components are evenly distributed. The solute is the substance that is solid and the solvent is the liquid in which the solute dissolves.

Some materials don’t dissolve in water but separate into pieces that do not settle out. Mixtures of water and non dissolved materials are known as suspensions. Human blood is an example of both a solution and suspension.

Acids, Bases, and pH Water can react to form ions. This happens to about 1 water molecule in 550 mllion. Water  Hydrogen + + Hydroxide - Equal numbers of positive and negative ions are produced which makes water neutral. The pH scale indicates the concentration of H+ ions. The scale ranges from Pure water has a pH of 7.

Each step on the pH scale is a factor of Stomach acid; 2.5 lemon juice; 4.5 Acid rain. 6 normal rainfall; 8.5 sea water; 10 Soap; 12.5 bleach Solutions with a pH below 7 on the scale are acids. They have higher concentrations of H+ ions in solution. Solutions with a pH above 7 are called bases because they have more OH- ions that H+

A buffer is a weak acid or base that can react with strong acids or bases to cause sudden changes in pH. Carbon Compounds Carbon atoms have 4 free electrons that can join with electrons from another atom to form a strong covalent bond. Carbon can also bond with other carbon atoms to form long chains. These carbon-carbon bonds can be single, double, or triple covalent bonds.

Macromolecules are giant molecules made from thousands of smaller molecules. Smaller units called monomers join together to form polymers. This is called polymerization. The millions of carbon containing compounds are classified into four groups of organic compounds: carbohydrates, lipids, nucleic acids, and proteins.

CARBOHYDRATES Sugars & Starches Energy Rich Also used for storage purposes Contains C, H, O 1:2:1 ratio of C:H:O End in –ose Ex. Glucose C 6 H 12 O 6 Simple sugars are monosaccharides like glucose, galactose, and fructose.

The large carbs formed from monosaccharides are either disaccharides or polysaccharides or starches. Animal starch is glycogen and plants have starch that they store or use in their structure, like cellulose

LIPIDS Contain mostly C, H, O H ratio is larger than 2:1 3 Fatty Acids & 1 Glycerol Saturated: No double bonds Unsaturated: Double or Triple Bonds Stored energy

NUCLEIC ACIDS Contain H,O,N,C,P Compose of strands of nucleotides Store and transmit genetic information. 2 kinds:(DNA) and (RNA) RNA contains the sugar ribose DNA contains the sugar deoxyribose.

PROTEINS Contain C, H, O, N, and possibly S. Composed of Amino Acids: amino group; carboxyl grp; -R grp Ex. Enzymes, Hormones, Hb, Insulin, Structural Proteins

Proteins can have up to 4 levels or organization 1.The sequence of amino acids in a protein chain (primary) 2.The amino acids in a chain twist like a helix or bend like a pleat (Secondary) 3.The chain itself is folded (Tertiary) van der waals and H bonds help to form globular proteins. 4.A protein that is assembled from 2 or more separate chain (Quaternary)

Chemical Reactions Take place when bonds are formed and broken. REMEMBER: All the chemical reactions that occur within an organism are called metabolism. Substances that undergo the reaction are called reactants, and the substances that form are called products.

In chemical equations atoms are neither created or destroyed, just rearranged. A chemical equation is written so that the same numbers of atoms of each element appear on both sides of the arrow. 2H 2 + O 2  2 H 2 0 Chemical reactions can absorb energy or release energy. The energy released is usually in the form of heat.

ENZYMES The energy that is needed to get a reaction started is called activation energy. Enzymes decrease activation energy. Complex proteins Increase the rates (speed) of reactions. Biological catalyst. End in -ase

Substances in the reactions are called substrates LOCK & KEY (Enzyme-Substrate Complex) SPECIFIC Named after reaction is catalyzes. Ex. To speed up the breakdown of Maltose the enzyme Maltase is used.

Enzyme movie clip

3 Factors that affect enzyme activity TemperaturepH Temperature pH Concentration of enzyme & substrate