Atomic Theories

1. Atomic Theories Did Dan just realize beryllium’s metal?

2. What did the element say when he got into a fight? Let me atom

3. Democritus • Greek philosopher • the originator of a theory on atoms • He said atoms are the smallest indivisible bodies from which everything else is composed

4. Dalton • Developed the first useful atomic theory • His theory was comprised of 4 postulates

5. The postulates • All matter consists of tiny particles called atoms 2. Atoms are neither created nor destroyed (based on???)

6. The postulates (cont.) 3. All atoms of a given element are identical and different from any other element 4. A given compound always has the same relative numbers and kinds of atoms

8. J.J. Thomson • Discovered that the atom has a substructure using a cathode ray • Discovered a negatively charged particle and named it the electron

9. Cont. • Couldn’t calculate the mass of an electron but figured out the ratio of its charge to its mass

10. T-money cont. • His model is called the mint choc. chip model because • The atom was electrons surrounded by a soup of positive charge to balance the electron's negative charge, like chips surrounded by mint ice cream.

12. Ernest Rutherford • Performed the gold foil experiment to discover the positively charged nucleus • He shot a beam of alpha particles at a piece of gold foil, while most went through, there were some that got scattered in every direction • Pg. 104

14. Are you Bohr’d yet? • Niels Bohr’s model depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus • Improvement on Rutherford's model

16. Modern Atomic Theory • Nucleus lies in the center of the atom • Electrons do not orbit in well-defined paths, rather they can be predicted in an area called an electron cloud

17. Something to break the monotony • When they broke open molecules, they found they were only stuffed with atoms. But when they broke open atoms, they found them stuffed with explosions.

18. Subatomic Particles Proton- Neutron- ELECTRON-

19. Proton • positive • found in the nucleus • has the mass of 1 amu

20. Joke 1 • A Hydrogen atom runs up to two other atoms yelling and waving his arms. "Help! A mugger just stole my electron!" One of the other atoms looks him over and asks, "Are you sure?" The first replies: "I'm positive!"

21. Neutron • Neutral • found in the nucleus • has the mass of 1 amu

22. Joke 2 • A neutron walks into a bar and orders a drink. When he attempts to pay, the bartender looks at him and says, "For you, no charge."

23. ELECTRON • Negative • found outside the nucleus • its mass is so small comparably that it is considered negligible

24. Joke 3 • SUBATOMIC PARTICLE STOREThe subatomic particle store had a sale last week.Electrons: $0.10Protons: $0.10Neutrons : free of charge

25. Atomic Number • # of protons • Atoms are neutral so the # of protons must equal ________ • The whole number found in the element box

26. Atomic Mass • Number of protons + number of neutrons • Measured in AMUs (Atomic mass units) • Where are the electrons?

27. Isotopes • Atoms that have the same number of protons but different number of neutrons • Do isotopes have the same charge? • Do isotopes have the same masses?

28. Isotope notation

29. Isotope Notation decoded • "X" represents the atom's elemental symbol.  • "A“--The mass number, (located in the upper left-hand corner) • "Z“-- The atomic number (found in the lower left-hand corner)

30. Last joke • Q: What did the thermometer say to the graduated cylinder? • A: "You may have graduated but I've got many degrees"