1. INSIDE THE ATOM

2. Three Topics: Section 1 How scientists model the atom What are charged particles What were Rutherford’s experiments REVIEW VOCABULARY Matter: anything that has mass and takes up space.

3. anode electron cloud cathode neutron alpha particle proton electron element New Vocabulary electrode with a positive charge region surrounding the nucleus in which electrons travel electrode with a negative charge particle in the nucleus of an atom that has the same mass as a proton and is electrically neutral fast-moving, positively charge bit of matter positively charged particle present in the nucleus of all atoms negatively charged particle located outside the nucleus of an atom matter made up of only one type of atom

4. Summarize early ideas about the structure of matter Matter was made of tiny particles and could be cut into smaller and smaller pieces until reaching a piece that could not be cut any more. This smallest piece is an atom. FIRST THOUGHTS

5. Dalton’s Ideas About matter Matter is made up of atoms All atoms of an element are exactly alike Atoms cannot be divided into smaller pieces Different elements are made of different kinds of atoms

6. Anode + Cathode - Mask Shadow Crooke’s Tube

7. Crooke’s Experiments He connected a battery to cathode (-) and anode (+) of a tube. He found that an object in the middle of the tube (mask) cast a shadow in a green glow. He concluded that the glow was caused by rays, or streams of particles.

8. MAGNET Rays are bent by magnet CATHODE RAYS thomson’s experiments

9. Thomson’s Experiments He placed a magnet next to the tube. The ray was bent by the magnet, showing the ray was made of particles, not light. He envisioned an atom as a sphere of positive charge with negatively charged electrons spread out evenly within. This is sometimes called The Plum Pudding Model.

10. rutherford’s experiment

11. Rutherford’s Experiment Experiment: Rutherford fired alpha particles at a thin film of gold. A screen lit up when it was hit by a charged particle. Expected Result: Almost all the alpha particles would go straight through. Actual Result: More particles bounced off than expected - some of them straight back! Conclusion: Positive and negative charges not evenly spread out. Positive charge concentrated into a nucleus.

12. After Rutherford’s model, how the extra mass in the nucleus was explained How electrons are thought to move in the most current atomic model Describe the following improvements to atomic theory. Neutron - neutral chargeElectron Cloud

13. The Atom Electrons Nucleus Protons Neutrons Electron Cloud + + + + + +

14. The Atom particlelocationcharge mass (relative) protonnucleus+2000 neutronnucleusnone2000 electron cloud -- 1

15. Section 2: The Nucleus What is radioactive decay? What is half-life? How are radioactive isotopes used? REVIEW VOCABULARY Atom: Matter is made up of atoms.

16. New Vocabulary number of protons in nucleus atom of an element with different number of neutrons number of neutrons plus number of protons release of nuclear particles and energy changing of one element into another through radioactive decay high-energy electron that comes from the nucleus amount of time it takes for half a sample of an element to decay atomic number isotope mass number radioactive decay transmutation beta particle half-life

17. Section 2: The Nucleus Carbon-12Carbon-13Carbon-14 Atomic number Number of protons Number of neutrons Mass Number 666 666 678 121314 Summarize what the strong nuclear force does. It holds the protons and neutrons in the nucleus.

18. carbon6C12 READING THE PERIODIC TABLE Atomic Number = # of protons, # of electrons Symbol Atomic Mass = # protons + # neutrons Name

19. Sequence steps of radioactive decay Neutronbecomesunstable The electron The proton Neutron splits into electron and proton. is ejected with a large amount of energy. stays in the nucleus. Atomic number increases by one.

20. HALF-LIFE You have 100 grams of Iodine-131, which has a half-life of 8 days. How much will be left after 24 days? 100 g Begin 50 g 8 days 25 g 16 days 12.5 g 24 days 1 2 3

21. HALF-LIFE You have 16 grams of Element-X, which has a half- life of 10 days. How much will be left after 40 days? 16 g Begin 8 g 10 days 4 g 20 days 2 g 30 days 1 g 40 days 1 2 34

22. HALF-LIFE You have 20 grams of Element-X, which has a half- life of 2 days. How much will be left after 6 days? 20g 10g 2 days 5 g 4 days 2.5g 6 days 1 2 3

23. Rate of Decay Start 1 st HalfLife 2 nd HalfLife 3 rd HalfLife Time Elapsed Mass 0 days 8 days 20 g10 g 16 days 24 days 5 g 2.5 g half-life the amount of time it takes for one half of a substance to decay.

24. Identify uses and hazards of radioactive material. USESHAZARDS RadioactiveMaterial Smoke detectors Medicine Date fossils Energy Radiation poisoning Long half-life