Lesson Overview 2.1 The Nature of Matter

Atoms What three subatomic particles make up atoms? Protons – in nucleus, positive charge Neutrons – in nucleus, neutral-no charge Electrons – outer shell, negative charge QUESTION: What overall charge does the nucleus have?

Elements and the Periodic Table pure substance that consists entirely of one type of atom Found on Periodic Table, represented by one- or two-letter symbols Atoms of element MUST have same number of protons (atomic number); can differ in number of electrons (ions) or neutrons (isotopes)

Elements and the Periodic Table ATOMIC NUMBER - # of protons in the nucleus of an atom (equal to # of electrons in neutral atom) MASS NUMBER – Number of protons and neutrons combined * To get # of neutrons, SUBTRACT atomic number from mass number

Elements and the Periodic Table EXAMPLE: What atom is shown to the right? How do you know? What is its atomic number? What is the mass number? What are the number of protons? What are the number of electrons? What are the number of neutrons?

Isotopes ISOTOPES - Atoms of the same element that differ in the number of neutrons they contain So isotopes of an elements have different MASS NUMBERS Isotopes have the same chemical properties (same # of electrons)

Radioactive Isotopes Some isotopes are radioactive, meaning that their nuclei are unstable and break down at a constant rate over time. Radioactive isotopes have a number of important scientific and practical uses. Radioactive dating to determine the ages of rocks and fossils Used to detect and treat cancer Used as labels or “tracers”

Chemical Compounds Chemical compound - formed by the chemical combination of two or more elements in definite proportions Compounds represented by chemical formula Example: Water Salt properties of a compound different from elements

Chemical Bonds Bonds involve the electrons of atoms Two main types: Ionic bonds – transfer of electrons, forming ions (charged atoms) – one positive (cation) and one negative (anion) Example: NaCl Covalent bonds – sharing of electrons, complete outer shell; form MOLECULES Example: water

Ionic Bonds

Covalent Bonds

Lesson Overview 2.2 Properties of Water

The Water Molecule How does the structure of water contribute to its unique properties? Because water is a polar molecule, it is able to form multiple hydrogen bonds, which account for many of water’s special properties.

Polarity oxygen end = slight (-) charge hydrogen end = slight (+) charge A molecule in which the charges are unevenly distributed is said to be “polar”

Hydrogen Bonding OPPOSITES ATTRACT! hydrogen bond – attraction between (+) hydrogen and (-) oxygen hydrogen bonding important to water’s special properties Cohesion Heat capacity

Cohesion, Adhesion, and Heat Capacity Cohesion - attraction between molecules of the same substance. (surface tension) Sticky Adhesion – attraction between molecules of different substances (capillary action) Meniscus Heat Capacity - amount of heat energy required to increase its temperature

Solutions Solute—the substance that is dissolved Solvent—the substance in which the solute dissolves; water known as “universal solvent” *Water’s polarity gives it the ability to dissolve both ionic compounds and other polar molecules (salts, sugars, minerals, gases) Suspensions - mixtures of water and undissolved material **Example for solution and suspension - BLOOD

Acids, Bases, and pH Water molecules sometimes split apart to form hydrogen ions and hydroxide ions (DISSOCIATION of WATER)

The pH Scale pH scale - indicates the concentration of H+ ions in solution Ranges from 0 to 14 pH of 7 = neutral (equal # of H+ and OH-) below 7 = acidic (more H+ than OH-) above 7 = basic, or alkaline (more OH- than H+)

The pH Scale Each step on the pH scale represents a factor of 10. For example, a liter of a solution with a pH of 4 has 10 times as many H+ ions as a liter of a solution with a pH of 5.

Lesson Overview 2.3 Carbon Compounds

The Chemistry of Carbon What do we know about CARBON? Symbol Atomic number Number of valence electrons ***Living organisms are made up of molecules that consist of CHONPS

Macromolecules The smaller units, or monomers, join together to form polymers. The monomers in a polymer may be identical or different.

Macromolecules 1. carbohydrates 2. lipids 3. nucleic acids 4. proteins Four major groups of macromolecules found in living things: 1. carbohydrates 2. lipids 3. nucleic acids 4. proteins

Carbohydrates made up of CHO usually in a ratio of 1 : 2 : 1. Functions – main source of energy structural purposes Examples: glucose (monosaccharide/monomer) starch (polysaccharide/polymer)

Lipids Made mostly of C & H’s and are generally not soluble in water Examples are fats, oils, waxes, and steroids Functions: Used to store energy (fat) Parts of biological membranes (phospholipids) waterproof coverings (waxes) chemical messengers (steroids/hormones)

Lipids Most are made up of glycerol and fatty acid chains Saturated vs. Unsaturated

Nucleic Acids made up of CHONP Nucleotides consist of three parts: a 5-carbon sugar, a phosphate group (–PO4), and a nitrogenous base. Functions: to store and transmit genetic information ***Two kinds – DNA and RNA

Protein made up of CHON monomer is an amino acid (a.a. come together to make proteins) Functions: Varied functions controlling the rate of reactions regulating cell processes forming cellular structures transporting substances into or out of cells helping to fight disease

Protein Amino acids have an amino group (–NH2), a carboxyl group (– COOH); R-group make each a.a. different Covalent bonds called peptide bonds link amino acids together to form a polypeptide

Levels of Organization Proteins have four levels of structure. 1. Primary structure is the sequence of its amino acids 2. Secondary structure is the folding or coiling of the polypeptide chain. (alpha/beta) 3. Tertiary structure is the 3-D structure 4. Quatenary structure – subunits come together

2.4 Chemical Reactions and Enzymes Lesson Overview 2.4 Chemical Reactions and Enzymes

Chemical Reactions Ex. The elements or compounds that enter into a chemical reaction are known as reactants. The elements or compounds produced by a chemical reaction are known as products.

Activation Energy Activation Energy - the energy that is needed to get a reaction started The difference between the required energy and the energy of the reactants is the activation energy (see graphs)

Enzymes Function – Enzymes speed up chemical reactions that take place in cells ***Temperature, pH, and regulatory molecules can affect the activity of enzymes

Nature’s Catalysts Enzymes are proteins that act as biological catalysts (speed up reactions by lowering activation energy) *Enzymes very specific

The Enzyme-Substrate Complex The reactants of enzyme-catalyzed reactions are known as substrates.

The Enzyme-Substrate Complex Substrates bind to a site on the enzyme called the active site The active site and the substrates compared to “lock and key”