Transcript Covalent Bonding
Chemistry of Life Chapter #2 ST 110 OBJECTIVES Define Terms related to Chemical organization Describe the structure of an atom Compare and contrast ionic and covalent bonding Distinguish between organic and inorganic compounds OBJECTIVES Discuss chemical characteristics of water Explain the concept of pH Discuss the structure and function of organic molecules Life is Chemistry Food Digestion Formation of bone tissue Contraction of muscles BIOCHEMISTRY Studying chemical aspects of life Levels of Chemical Organization Matter Molecules Atoms ATOMS Composed of subatomic particles Protons Electrons Neutrons Atoms Nucleus Atomic number Atomic mass Atoms Electrons stay in certain limits called orbitals Each orbital can hold two electrons The closer to the nucleus, the lower the energy level Orbitals The second energy level has four orbitals How many electrons can be held in the second energy level? IMPORTANCE???? The outer number of electrons determines how the atom “behaves chemically” Elements Element- pure substance of only one type of atom Each element has a symbol Example: Hydrogen Nitrogen Potassium C.O.H.N. Four atoms that make up 96% of the human body Carbon Oxygen Hydrogen Nitrogen Molecules and Compounds Atoms unite with each other to form molecules. Compounds have more than one element in them. Compounds The number of atoms in each molecule is expressed by a subscript Example: CO2 = carbon dioxide one carbon, two oxygen's H2O2 = hydrogen peroxide two hydrogen’s, two oxygen’s Compounds/Chemical Bonding Chemical bonds form to make atoms more stable An atom is stable when it’s outer energy level is full Atoms react to each other to make their outer most level full Ionic Bonds Electrons are donated One atom will become negatively charged, and the other will become positively charged. +++POSITIVE ION +++ • an ion that has given up its electron to another atom ---NEGATIVE ION--• an ion that has borrowed an electron IONIC BONDS Na-sodium – donates one electron then becomes positive Cl-chlorine- borrows one electron then it becomes negative Na + Cl = NaCl (sodium chloride) IONS Ionic molecules dissolve easily in water Dissociate- when ionic bonds break apart Electrolytes- are molecules that form ions when dissolved in water QUESTION??????? What are the four main atoms that make up 96% of the human body? QUESTION???????? What is a positive ion? What is a negative ion? Covalent Bonds Covalent Bonds Atoms can fill their energy level by sharing electrons Covalent bonds do not break apart in water Covalent Bonding Question??? What is ionic bonding? Question???? What is Covalent bonding? Inorganic Chemistry Inorganic compounds do not contain Carbon-Carbon , or Carbon Hydrogen bonds Few inorganic compounds have carbon in them Inorganic compounds are smaller and less complex than organic compounds H2O Inorganic Compound Why is water considered inorganic? Is it a solvent, or a solute? Solvent is a substance in which other substances are dissolved. Water is a Solvent !!! Solute is a substance that dissolves into another substance. Salt is a solute!!! Mixture- a blend of two or more kinds of molecules Aqueous solution - When water is the solvent for two or more kinds of molecules Dehydration Synthesis Synthesis- Is the reaction in which two reactants combine to form a product Dehydration synthesis can only occur when a water molecule is removed from the reactants and then they bind to form a larger product. Hydrolysis Water disrupts the bonds in large molecules The larger molecule is broken into smaller molecules Hydrolysis is the reverse of dehydration synthesis Chemical Reactions Always Involve Energy Transfers Some energy is stored as potential energy in the chemical bonds Ex: ATP (adenosine triphosphate) pH Balanced ! Herbal Essence Shampoo? or something else? pH balance is 7 Which way does an ACID go on the pH scale???? Which numbers on the pH scale represent a base? Acids are compounds that produce an excess of H+ ions Bases (alkaline) are compounds that produce an excess of OH- ions (or decreased in H+) Isotopes Isotopes- two atoms with the same atomic number, but different atomic mass Metric System 1 meter= 39.37 inches 1 centimeter= 1/100 meter 1 millimeter= 1/1,000 meter I micrometer= 1/1,000,000 meter End of Day 1 Questions??? Organic Chemistry Much more complex than inorganic compounds Larger than inorganic compounds Organic Chemistry Four major types of organic compounds Carbohydrates Lipids Proteins Nucleic Acids Carbohydrates Carbo-carbon hydrate-water Basic unit of a carbohydrate is called monosaccharide EX: Glucose important monosaccharide Primary source of energy Carbohydrates Disaccharide- a molecule made up of 2 saccharide units (double sugar) EX: Sucrose- table sugar Lactose- milk sugar • After eaten, the body digests them to form monosaccharides to be used as cellular fuel Carbohydrates Polysaccharides- many saccharides joined together EX: glycogen and starch Each glycogen molecule is a chain of glucose molecules joined together Liver cells and muscles cells form glycogen. Excess glucose in blood is stored for later use. Carbohydrates Carbohydrates have potential energy stored in their bonds Lipids Lipid- fat and oils At room temperature Fats- solid lipid Oils- liquid lipid Lipids Triglycerides • Bonds can be broken apart to yield energy • Store energy in cells for later use Lipids Phospholipids The phosphorus containing unit in each molecule forms a head that attracts water Two fatty acid tails repel water Cholesterol Performs several important functions in the body Combines with phospholipids in cell membrane to stabilize bi-layer structure Body uses cholesterol to make steroid hormones. Estrogen, testosterone, cortisone Proteins Very large molecule made of amino acids Amino acids are held together by peptide bonds Two types of proteins Structural Functional Proteins Structural Proteins Form Structures of the body Collagen- fibrous protein that holds many tissues together Keratin- forms tough waterproof fibers in outer layer of the skin Proteins Functional Proteins Participate in chemical processes Hormones, cell membrane channels receptors, enzymes Enzymes Catalysts- aid in chemical reactions Lock-and-key model Proteins can combine with other organic molecules to form glycoproteins lipoproteins Nucleic Acid DNA-deoxyribonucleic acid • Master code • Double helix Nucleic Acid RNA- ribonucleic acid Working copy Nucleic Acid Made of nucleotide units Sugar (ribose, or deoxyribose) Phosphate- nitrogen based adenine, thymine or uracil, guanine cytosine What are the four major types of organic compounds found in the body? What is glycogen? What is the primary source of energy for cells? What are lipids? What are proteins made of? What is an enzyme? What are the two types of nucleic acids? What are the nitrogen bases? What shape is DNA? End of Day 2 Questions???