1. Chapter 2 Matter is Made up of Atoms

2. Section 2.1 Section 2.2 Atom Atomic Theory Hypothesis Theory Scientific Law Electron Proton Isotope Neutron Nucleus Atomic Number Mass Number Electromagnetic Spectrum Valence Electron Lewis Dot Diagram Vocab

3. The Scientific Method Broken down into 5 Steps  Observation  Hypothesis  Experiment  Theory  Scientific Law

4. Observation What would happen if I lit Mr. T on Fire?

5. Hypothesis If I light Mr. T on fire, he will be upset with me!

6. Experiment Let’s Light Mr. T on Fire!

7. Experiment Yep…He’s Mad!

8. Theory I wonder if Mr. T would be upset if other people lit him on fire as well???

9. Scientific Law Once the experiment is tested by many people without the hypothesis changing, the theory becomes a Scientific Law (Like Gravity)

10. The Atom John Dalton first proposed the atom He gave 3 statements about atoms

11. Dalton 1) All matter is made up of atoms

12. Dalton 2) Atoms are indestructble Law of conservation of matter– you cannot create nor destroy matter

13. Dalton 3) Atoms of one element are alike, but different from other elements

14. The Electron J.J. Thomson next proposed the electron He used a cathode ray tube to prove its existence

15. Protons and Neutrons Ernest Rutherford later discovered protons and neutrons

16. Protons and Neutrons He found these to be in the nucleus using the gold foil experiment

17. Where do we find these subatomic particles? Electrons Protons and Neutrons

18. How Small is the Nucleus?

19. What about Masses? ParticleSymbolChargeMass # Protonp+p+ 1+1 Neutronn0n0 No Charge1 Electrone-e- 1-0

20. Atomic Number = Number of Protons and Electrons! H Hydrogen 1 1.0079 Element Atomic Number Atomic Mass

21. Finding Mass Number Mass number is similar to atomic number #p + + #n o = Mass Number Remember, p + = atomic number

22. Example Find the number of protons, neutrons, and electrons in Sodium (Na). The mass number for our sodium atom is 25. Note – we can also write this Na-25

23. Mass # vs Atomic # The atomic number is the average mass of all of the isotopes of a particular atom.

24. Think Critically Why don’t electrons add to the atomic number or mass number of an element?

25. Electromagnetic radiation Waves are given off by radiation  Short waves have a high frequency  Long waves have a low frequency

26. Electromagnetic spectrum

27. Electrons getting excited Electrons also can get excited and let off energy This will result in the electron giving off a color