1. Electroscope Lab

2. Before the Lab What did the leaves look like?  Hanging straight down. What is making them stay in that position?  Gravity

3. So….What did you observe? What happened to the leaves when you touched the ball after being rubbed on the fabric?  They Spread apart What happened to the rods when they were rubbed with the fabric?  They became either positively or negatively charged.

4. Observations…. Why did the leaves spread apart?  Electrons were transferred off or on the rod. What happened when you touched the ball of the electroscope?  The leaves returned to their natural position  Electrons transferred to or from the rod to your finger to be neutral  Neutral---equal electrons and protons  Everything wants to be neutral

5. Observations cont… Which piece of fabric added electrons to the rod?  Wool---which gave the white rod a negative charge Which piece of fabric took electrons away from the rod?  Silk---which gave the clear rod a positive charge

6. Observations…. How do we know that one piece of fabric made the rod have a positive charge and the other have a negative charge?  Part D of the activity  The leaves moved closer when the white rod was close to the ball of the electroscope.  Started to become Neutral  If they were both negative/positive the leaves would have gotten farther apart.

7. Conclusion What is the name of this force that pushes the leaves apart by transfering electrons?  Electrostatic Force What can we infer from this lab?  Opposite charges attract  Like charges repell  The charge extends beyond the particle  This is the 2 nd strongest force in the atom

8. Elements  Can’t be divided into any simpler substances. Atoms  Smallest particle of an element that still have all the properties of that element.

9. Subatomic Particles  Proton—(+) charge, nucleus  Neutron—(0) charge, nucleus  Electron—(-) charge, electron cloud

10. Elements and Atoms  90 naturally occurring elements  20 synthetic elements What is synthetic?  Man made