1. The Atom Smallest unit of an element that can exist alone Greek for “uncuttable” Anatomy of an Atom: Electrons, Protons, Neutrons The Nucleus Proton Positive charge Determines the atomic number Number of Protons determines the number of Electrons Neutron No charge Atomic weight - # of Protons = # of Neutrons

2. Electrons Negative charge Atomic number tells you the number of electrons Resides in the “shells”, orbits, or levels

3. Organized representation of the chemical elements Dimitri Mendeleev February 17, 1869 63 elements 113 elements Row (Period) Left to right w/ increasing atomic number Number from 1 to 7 Columns (Family) Number of electrons in the outer orbit Groups A Group (Representative elements) B Group (Transition elements) Group VIIIA Noble or inert gases Metals, Semiconductors, & Nonmetals More on this later – stay tuned

5. The Element Symbol Atomic number Total number of electrons Total number of protons Electrical charge Electrons – minus Protons – plus Neutrons – no charge Atomic weight (Nucleus) Protons + Neutrons = atomic weight

6. Electron Configuration Energy Levels (Shells) Level I – 2 Level II – 8 Level III – 8 (first 20 elements) (18) Level IV – 32

7. Putting it all together... Sodium Na Atomic # - 11 Level I (Shell) - 2 Level II - 8 Level III – 1

8. Try this one... Chlorine Cl

9. Atomic # 17 Level I – 2 Level II – 8 Level III – 7

10. What does the Periodic Table Tell Us? Element symbol & name Atomic Number of the element Number of electrons Number of protons Number of neutrons Number of electrons in the outer shell Atomic weight

11. Metals, Nonmetals, & Semiconductors 80% of the elements are metals Ion An element with an unbalanced electron charge – either plus or minus Positive ions – lose electrons Metals Negative ions – gain electrons Non-metals Remember – the number of protons determines the charge

12. Ions When the number of protons is greater than the number electrons it is a positive (+) charged ion. When the number of electrons is greater than the number of protons it is a negative (-) charged ion.

13. Metals Elements with 1 – 3 electrons to lose Positive ion Non-metals Elements with 1 -3 electrons to gain Negative ion

14. Check this out... http://www.vanderkrogt.net/elements