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Lesson Overview The Nature of Matter Lesson Overview 2.1 The Nature of Matter Lesson Overview 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? Lesson Overview The Nature of Matter Elements and the Periodic Table Elements pure substance that consists entirely of one type of atom Found on Periodic Table, represented by one- or twoletter symbols Atoms of element MUST have same number of protons (atomic number); can differ in number of electrons (ions) or neutrons (isotopes) Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter 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? Lesson Overview The Nature of Matter Isotopes o ISOTOPES - Atoms of the same element that differ in the number of neutrons they contain o So isotopes of an elements have different MASS NUMBERS o Isotopes have the same chemical properties (same # of electrons) Lesson Overview The Nature of Matter 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. o Radioactive dating to determine the ages of rocks and fossils o Used to detect and treat cancer o Used as labels or “tracers” Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter Chemical Bonds Bonds involve the electrons of atoms Two main types: o Ionic bonds – transfer of electrons, forming ions (charged atoms) – one positive (cation) and one negative (anion) Example: NaCl o Covalent bonds – sharing of electrons, complete outer shell; form MOLECULES Example: water Lesson Overview Ionic Bonds The Nature of Matter Lesson Overview The Nature of Matter Covalent Bonds Lesson Overview The Nature of Matter Lesson Overview 2.2 Properties of Water Lesson Overview The Nature of Matter 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. Lesson Overview The Nature of Matter Polarity oxygen end = slight (-) charge hydrogen end = slight (+) charge A molecule in which the charges are unevenly distributed is said to be “polar” Lesson Overview The Nature of Matter Hydrogen Bonding OPPOSITES ATTRACT! hydrogen bond – attraction between (+) hydrogen and (-) oxygen hydrogen bonding important to water’s special properties • Cohesion • Heat capacity Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter Acids, Bases, and pH Water molecules sometimes split apart to form hydrogen ions and hydroxide ions (DISSOCIATION of WATER) Lesson Overview The Nature of Matter 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+) Lesson Overview The Nature of Matter 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 The Nature of Matter Lesson Overview 2.3 Carbon Compounds Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter Macromolecules The smaller units, or monomers, join together to form polymers. The monomers in a polymer may be identical or different. Lesson Overview The Nature of Matter Macromolecules Four major groups of macromolecules found in living things: 1. carbohydrates 2. lipids 3. nucleic acids 4. proteins Lesson Overview The Nature of Matter 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) Lesson Overview The Nature of Matter 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) Lesson Overview The Nature of Matter Lipids • Most are made up of glycerol and fatty acid chains • Saturated vs. Unsaturated Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter 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 Lesson Overview The Nature of Matter Lesson Overview 2.4 Chemical Reactions and Enzymes Lesson Overview The Nature of Matter 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. Lesson Overview The Nature of Matter 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) Lesson Overview The Nature of Matter Enzymes Function – Enzymes speed up chemical reactions that take place in cells ***Temperature, pH, and regulatory molecules can affect the activity of enzymes Lesson Overview The Nature of Matter Nature’s Catalysts Enzymes are proteins that act as biological catalysts (speed up reactions by lowering activation energy) *Enzymes very specific Lesson Overview The Nature of Matter The Enzyme-Substrate Complex • The reactants of enzyme-catalyzed reactions are known as substrates. Lesson Overview The Nature of Matter 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”