Levels of Biological Organization

1. Levels of Biological Organization

2. The Chemical Context of Life

3. Chemical Elements and Compounds • Matter- anything that takes up space : has a mass and a volume. • Example: DNA, ________ • Is air matter? Yes OR No • How can we prove this?

5. Element- a substance that cannot be broken down into other substances • Example: sodium (Na) and chlorine (Cl) • Compound- a substance consisting of two or more elements. Example: Salt NaCl, HCO3 (important buffer involved in respiration)

6. Life requires approximately 25 chemical elements These six elements make 98% of all living organisms: - Carbon - Hydrogen - Nitrogen - Oxygen - Phosphorous -Sulfur (sulphur) (The remaining % = K, Ca, Na etc)

7. Trace Elements- small amount required by an organism, but very important. - example Iron or Iodine

8. Iodine Deficiency

9. Iron Deficiency

10. Atom-smallest unit of matter made up of protons, electrons, and neutrons. Neutron: no charge Proton :+ charge Electron: -charge

11. Ion-Charged particle -cation: positive ion (Na1+) -Has one less electron, therefore it is positive -anion: negative ion (Cl1-) -Has one more electron, therefore it is negative

12. Atomic Number- Indicates the number of protons (can also predict size of the atom) He = 2 protons C = 6 protons (if the atom is neutral then the atomic # = the # of electrons) • Mass Number- sum of the protons plus the number of neutrons.

13. Standard Notation: 4 atomic mass # He element symbol 2 atomic # 12 C 6

15. Isotope- Different atomic forms of an element due to a different number of neutrons. Example: 12 13 14 C C C 6 6 6

16. Radioactive Isotopes are useful in -carbon dating -metabolism tracers -medicine

18. Why do some ions have less electrons? • Why do some ions have more electrons? • Think back to chemistry 11/Science 10/Science 9 • Outer Electron Shells/orbitals (valence electron shells) Bohr Models: First Shell: 2 electrons Second Shell: 8 electrons Third Shell: 8 electrons Fourth Shell: 18 electrons

19. Bohr Models • Lithium atom Chlorine atom

20. Bohr Models • Lithium Ion Chlorine Ion

21. To make you chuckle