Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
General Chemistry Review for the biological sciences Chemical Elements • Each element consists of unique atoms • Represented by symbols—H, Na, Au, etc. • 92 naturally occurring elements (what are they?) – About 25 are considered essential to life – 4 make up > 95% of living matter • Carbon • Hydrogen • Oxygen • Nitrogen Chemical Elements • Other significant elements – Ca, P, K, S, Na, Cl, Mg • Trace elements – Fe, I, Cu, Zn, Co Atoms • The smallest particle of an element that has the qualities of that element • Made up of smaller sub-atomic particles • Cannot be broken down into simpler substances by ordinary means Sub-atomic particles Neutrons •neutral (no) charge •symbol n0 •mass = 1+ amu nucleus Protons •positive charge •symbol p+ •mass = 1 amu + + Electrons •negative charge •symbol e•located in electron cloud •Mass = 1/1840th amu The atom (He) The attractions between the positive charges in the nucleus and the negative charges of the electrons keep the electrons in the vicinity of the nucleus. molecules • Atoms of two or more different types chemically combined • Chemically different than the atoms that make them up • Molecules combine to form compounds water: a colorless, odorless liquid (at ordinary temps); necessary for life a water molecule H2O Hydrogen: a colorless, odorless gas; explosive! oxygen: a colorless, odorless gas; supports combustion So…how are atoms held together in a molecule? CHEMICAL BONDS! • Ionic: the giving and taking of electrons • Covalent: the sharing of electrons • Hydrogen: the attraction of + and - Ionic Bonds • Exchange of electrons – One atom takes electrons & the other donates them • Forms charged particles called ions • ex—sodium chloride Covalent Bonds • Sharing of electrons • Between nonmetals – Cl + Cl – CH4 Covalent Bonds Non-polar Polar Covalent Bonds non-polar • Equal sharing of electrons between two or more atoms • Carbon, Hydrogen – CH4 – C2H6 polar • Unequal sharing of electrons between atoms • Forms polar molecules • Water, sugar, alcohol Hydrogen bonds • The attraction between the +charged portion of one polar molecule and the –charged portion of another molecule • Found in water, proteins, DNA Moving on to the chemistry of living things… CARBON AND MACROMOLECULES Carbon is the backbone • Carbon has 4 valence electrons • =Versatility – Chains (straight or branched) – Rings – Single, double and triple bonds – Isomers Functional Groups • Certain groups of atoms that may be attached to a carbon skeleton and give organic compounds distinctive features. • Attachments that replace one or more of the hydrogens bonded to the carbon skeleton http://yellowtang.org/images/five_principal_func_c_la_784.jpg Biomolecules or Macromolecules • Polymers produced by living things • Polymers are – Large molecules – made up of smaller, repeating units called monomers • Monomer + monomer + monomer + ….. creates the polymer – Condensation reaction/dehydration synthesis/ polymerization • Reverse reaction is hydrolysis Polymer examples monomers Carbohydrates Starches, cellulose, Pasta, potatoes, etc. Simple sugars Lipids Fats, oils, waxes Glycerol & fatty acids Proteins Meat, muscle tissue, enzymes, hair, etc. Amino acids Nucleic acids DNA & RNA nucleotides THE END