1. Rutherford’s Experiment in 1911 (proving atoms are mostly space with dense small nucleus) Tahoma Jr. High 8 th Grade Science Maple Valley, WA drawing not even close to being to scale

2. Ernest Rutherford (1871 – 1937) New Zealand born – British scientist (they had better labs in Europe) He is known as “The Father of Nuclear Physics” (for figuring out atomic structure) and remember… atoms are so small they are essentially invisible, and yet he did this 100 years ago!

3. Rutherford wanted to find out what was inside atoms that made up all matter. He needed a small “gun” to shoot very small particles through the atom. Luckily, there was such an “atomic” gun available – with newly discovered radioactivity.

4. In 1896 – Frenchman Henri Becquerel stored some unusual rocks on undeveloped chemical film sealed in black paper inside his desk drawer. Later, when he developed the film, the rock had left an image on the film. Somehow, particles went through the paper and reacted with the film – in the dark, where there was no light.

5. a BECAUSE I LOVE U (get it?! – what does “U” stand for in chemistry?)

6. Rutherford put a small amount of radioactive material in a lead box with a hole in one end – particles could only come out the hole (lead is very dense). Where have you had lead used to protect you from x-rays? Lead aprons put over you at dentist/hospital. Superman’s X-ray vision does not work through lead. (there’s a lot of good science in science-fiction!)

7. The small particles were shot at a VERY VERY thin piece of gold foil. Gold is made of very big heavy atoms (why it weighs so much for its size) and can also be pounded into very thin sheets without breaking… making the sheet only a few atoms thick.

8. Surrounding the gold foil was a screen that would glow when hit with particles (similar to how your TV works)

9. Rutherford found that most particles went through as if nothing was in the way (atoms are mostly space) – but a few would get deflected at some pretty sharp angles (meaning they hit something very dense and bounced off).

10. He also discovered the nucleus was positively charged (leading to his discovery of protons) and that radioactive materials decay into different elements. Atoms, therefore, must have a small, but VERY dense nucleus!

11. We are going to be just thinking of atoms “from the outside”. Even though Rutherford (and others) were able to figure out what was going on inside of an atom (think about how small these atoms are and they were doing this over 100 years ago!) we won’t be dealing with the inside of the atom in 8 th Science. table salt crystal sodium atoms = purple chlorine atoms = green

12. But you probably never heard of him because most people can’t appreciate what he did since they don’t know much about chemistry or atoms. But now you do ! He won the Nobel Prize for Chemistry and became so famous, when he died, he was buried next to Sir Isaac Newton in England. end show