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Chemistry of Life

Scientists devised experiments to shed light on whether different fish species of the same genus compete in their natural habitat. They constructed 12 ponds, identical in chemical composition and physical characteristics. Then they released the following individuals into each pond:

shoshana-gallagher
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Chemistry of Life

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  1. Scientists devised experiments to shed light on whether different fish species of the same genus compete in their natural habitat. They constructed 12 ponds, identical in chemical composition and physical characteristics. Then they released the following individuals into each pond: • Ponds 1,2,3 Species A 300 per pond • Ponds 4,5,6 Species B 300 per pond • Ponds 7,8,9 Species C 300 per pond • Ponds 10,11,12 Species A,B,C 300 of each per pond • Does this experimental design take into consideration all factors that can affect the outcome? If not, how would you modify it?

  2. Chemistry of Life

  3. Elements of Life • Carbon • Hydrogen • Oxygen • Nitrogen } 96% of life

  4. Atom Structure Review

  5. Atomic Number • = Number of protons

  6. Mass Number • = Number of protons + Number of neutrons

  7. Isotopes – Variant forms of elements • Isotopes occur because of variations in neutron number (proton number is always the same)

  8. Radioisotopes • Spontaneous decay of nucleus • Emits energy • Used as radioactive tags • http://www.buzzle.com/articles/radioactive-isotopes-in-medicine.html

  9. Electrons and Energy Levels • Located in energy levels (shells) • Shells closest to nucleus are lower energy levels • Shells farther away are higher energy levels

  10. Electrons and Energy Levels • Chemical properties depend on the number of valence electrons

  11. Orbitals • Only 2 electrons per orbital

  12. Chemical Bonding • Ions = charged particles • Cations = + • Anions = - • Ionic bonding • Cations and anions attract • Forms salts http://bcs.whfreeman.com/thelifewire/content/chp02/02020.html

  13. Chemical Bonding • Covalent bonds • Atoms share valence electrons http://bcs.whfreeman.com/thelifewire/content/chp02/02020.html

  14. Chemical Bonding • Polar and Nonpolar Covalent Bonding • Polar – electrons are shared unequally • Charge difference

  15. Chemical Bonding • Polar and Nonpolar Covalent Bonding • Nonpolar – electrons are shared equally • No charge difference

  16. Hydrogen Bonding • Weak attraction between H and electronegative atom • Found in: • H2O • Proteins • Nucleic Acids Easily Broken

  17. http://www.stolaf.edu/people/giannini/biological%20anamations.htmlhttp://www.stolaf.edu/people/giannini/biological%20anamations.html

  18. Properties of Water • Cohesion (water molecules cling to each other) • Causes surface tension

  19. Properties of Water • Adhesion (water molecules cling to other molecules) • Allows for “capillarity” • Water travels upward through vascular tissue

  20. Properties of Water • Temperature Stabilization • heat does not immediately change temperature

  21. Properties of Water • Evaporative cooling • As H2O evaporates, remaining liquid area is cooler • Molecules with more heat energy leave as vapor

  22. Properties of Water • Solvent properties • Polarity allows water to “tear apart” molecules

  23. Acids, Bases and Buffers • Water dissociation

  24. Acids, Bases and Buffers • Water has neutral pH because of equilibrium between H+ and OH- • Acids – proton (H+) donors • Bases (alkaline fluids) – proton acceptors (OH-)

  25. Acids, Bases and Buffers • Buffers – regulate pH by countering slight changes • Accept H+ when it is in excess • Donate H+ when they are depleted http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/buffer12.swf

  26. Explain, with reference to its properties, the significance of water as a coolant, a means of transport and as a habitat.

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