1. * Objective 2 * atom * matter * periods * electron * proton * neutron * nucleus * Mendeleev * atomic number * electron shell * valence electron http://www.youtube.com/watch?v=ssaUusY6hWMhttp://www.youtube.com/watch?v=ssaUusY6hWM (the elements song)

2. * What is the difference between an atom and an element? * Describe Mendeleev’s contribution to the periodic table system * What does the atomic number tell you about an element? * Describe how you draw an accurate model of an element – what steps do you take and what information do you need from the periodic table?

3.  A million atoms would fit on the head of a pin.  Atoms are made of mostly empty space  An element is an atom with a specific number of protons in the nucleus.  Elements are what matter is composed of

4. * An atom with a specific number of protons in the nucleus. Phosphorous Silicon Sulfur 1669 Hennig Brand German Alchemist Phosphorous from urine Glows with oxygen If you change the number of protons – what happens?

5. Periodic Table * Dmitri Mendeleev * 1834-1907 * Russian chemist * Predicted new elements Patterns in the table  The atomic number of an element is the number of protons in the nucleus. Organization?  The period = row. The period tells you the number of electron shells. Organization?  Each element is represented by a symbol.

6. Number of protons = number of electrons How do you calculate the number of neutrons? How do you know the number of electron shells? Electron configuration 1s 2 2s 1

7. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 How would you draw an isotope of potassium ( 40 K) ?