2. Regents Biology Ch. 6The Chemical Basis of Life Atoms, Elements, & Molecules Why are we studying Chemistry?

3. Regents Biology ProtonNeutronElectron Hydrogen 1 proton 1 electron Oxygen 8 protons 8 neutrons 8 electrons  Everything is made of matter  Matter is made of “ATOMS” Atoms are the smallest unit of matter

4. Regents Biology Section 2.1 Atoms, Elements, and Molecules Atomic Number – the number of protons located in the nucleus of an atom. Atomic Mass – the number of protons and neutrons together. (also called the “Mass Number”)

5. Regents Biology  About 25 elements are essential for life  Four elements make up 96% of living matter: carbon (C) hydrogen (H) oxygen (O) nitrogen (N) Section 2.1 Atoms, Elements, and Molecules

6. Regents Biology The World of Elements C Different kinds of atoms = elements H ON PSNa K Mg Ca

7. Regents Biology Molecules of Life  Put C, H, O, N together in different ways to build living organisms  What are organisms made of?  carbohydrates  sugars & starches  proteins  fats (lipids)  nucleic acids  DNA, RNA

8. Regents Biology Elements come together to make compounds Compound – A substance containing 2 or more elements. Example Table Salt (aka – NaCl) Elements  Compounds Section 2.1 Atoms, Ions, and Molecules

9. Regents Biology Questions????