1. Atoms, Elements

2. Atoms Protons Neutrons Electrons Contain 3 particles

3. Nucleus Consists of: Neutrons Protons The Neutron What are the characteristics of the particles? No Charge Determines isotope The Proton Positive charge Determines element The Electron Negative charge Participates in chemical reactions Outer shell e - determine chemical behavior

4. Atoms The number of electronsThe number of electrons  Is equal to the number of protons Electrons in space around the nucleusElectrons in space around the nucleus

5. What is the atomic number? Number of protons Number of protons plus neutrons 13 Al 26.9815 Atomic number Symbol Mass number What is the mass number?

6. Atomic Number? C atom with Carbon Mass Number? ____ ____ protons ____ protons ____ neutrons ____ neutrons 6 12 6 6

7. Helium Atomic Number? ____ Mass Number? ____ He Protons? ____ Neutrons? ____2 2 2 4 4 2

8. Biologically Important Elements Oxygen (O) Carbon (C)Hydrogen (H) Nitrogen (N) Trace elements Calcium (Ca) Phosphorus (P) Potassium (K) Sulfur (S) Sodium (Na) Chlorine (Cl) Magnesium (Mg)

9. Bonds are formed or broken down in chemical reactions Ionic bonding –Atoms losing or gaining electrons to complete their outer shells

10. Covalent bonding –Sharing electrons

11. Covalent bonding –Sharing electrons

12. Covalent bonds can be: Single Double Triple

13. Water Our cells are composed of 70% – 95% water Water covers 3/4 th of the earth

14. The electrons in its covalent bonds are shared unequally How are the hydrogen and oxygen atoms bonded together? Hydrogen bonding?Covalent bonding? Creates POLARITY Water

15. Hydrogen bonding?Covalent bonding? How are water molecules bonded together? The polarity of water results in weak electrical attractions between neighboring water molecules Creates HYDROGEN bonding

16. An acid What is: – A compound that accepts H+ ions and removes them from solution? A base A pH scale – A chemical compound that donates H+ ions to solutions? – A measure of H+ ion concentration in a solution?

17. A pH Scale Acidic Basic Neutral pH 7 – Biological range maintained at ~ 6.5 – 7.5 Blood ~ 7.2 – 7.4 [H+] = [OH+]