Improvements

1. Improvements • More info about the people, but take only 1-2 days to cover them

2. Bell Work 12/9/13 • Start new bellwork titled “Atoms” • What do you remember about atoms? (their structure, the subatomic particles, the charges…) • W5SAYWoS

3. Happy 16th Birthday Kendle Rivera!

5. Atoms: The Building Blocks of Matter

6. Prior knowledge

7. Schedule • Today • Elements to memorize • Notes on history of atom • Worksheet • Monday • Electron configuration • Tuesday • Isotope quiz!

8. Elements to Memorize • 1-20, 26-30, 47, 50, 78-80, 82 # Name Symbol How remember

9. Today you are going to…take notes on the history of the atom. So you can…explain how & by whom the parts of the atom have been discovered. You’ll know you’ve got it when you can • List the scientists of the atom and their achievements

10. History of Atom Overview Video • http://www.youtube.com/watch?v=B2aFTNhgyII&feature=related

12. Leucippus & Democritus • Democritus460 BC - 370 BC • Student of Leucippus • Believed all matter is made up of various imperishable, indivisible things which he called atoma, or “indivisible units” • Basically, they named the atom!

13. Aristotle • 384 BC – 322 BC • Believed matter consisted of 4 basic elements • Wrong, but people believed him because he was popular with important people & the church.

14. Alchemists • 1100’s • European “scientists” that tried to make gold from other metals • Couldn’t be done • Added ideas of observation & experimentation! • Recorded info on properties of matter

16. Bell Work 12/10/13 • What did Democritus think? • What did Aristotle think? • What did alchemist try to do? How did this advance science?

17. John Dalton • 1766 – 1844 • Had a theory…

18. Dalton’s Atomic Theory • All matter is composed of atoms • Atoms of a given element are identical in size, mass, and other properties; atoms of different elements are different • Atoms cannot be subdivided, created, or destroyed • Atoms of different elements combine in simple whole-number ratios to form compounds • In chemical reactions, atoms are combined, separated, or rearranged.

19. Dalton’s Atomic Theory(Simplified) • All matter is composed of atoms • Atoms of same element are identical; atoms of different elements are different • Atoms cannot be subdivided, created, nor destroyed • Atoms of different elements combine to form compounds • In chemical reactions, atoms are rearranged.

20. Modern Atomic Theory • Still True… • All matter is composed of atoms • Atoms of any one element differ in properties from atoms of another. • Different • Atoms of the same element may have different masses! (Called isotopes) • Atoms are divisible (not by ordinary chem. means). • Nuclear reactions!

22. Discovery of the Electron In 1897, J.J. Thomson used a cathode ray tube to deduce the presence of a negatively charged particle...DISCOVERED THE ELECTRON!! Cathode ray tubes pass electricity through a gas that is contained at a very low pressure.

23. Discovery of the Electron TV Demo! Cathode rays – stream of electrons e- moved ______________ the positive charged plate

25. Some ModernCathode Ray Tubes

26. Conclusions from the Study of the Electron • Cathode rays have identical properties regardless of the element used to produce them. All elements must contain identically charged electrons. • Atoms are neutral, so there must be positive particles in the atom to balance the negative charge of the electrons

27. J.J. Thomson’s Atomic Model I love me some plum puddin’! Discovered all electrons have equal charge, but couldn’t measure mass or charge of the electrons. Thomson believed that the electrons were like plums embedded in a positively charged “pudding,” thus it was called the “plum pudding” model.

29. Mass of the Electron 1909 – Robert Millikan determines the mass of the electron. Enables him to calculate the charge too! The oil drop apparatus Mass of the electron is 9.109 x 10-31 kg

30. Conclusions from the Study of the Electron • Electrons have so little mass that atoms must contain other particles that account for most of the mass

32. 1911: Rutherford’s Gold Foil Experiment • Fired alpha particles (helium nuclei, ___ charge) • Particles were fired at a thin sheet of gold foil • Particle hits on the detecting screen (film) are recorded • “Gold foil” demo

33. Rutherford’s Findings • Mostof the particles passed right through • A fewparticles were deflected • VERY FEW were greatly deflected “Like howitzer shells bouncing off of tissue paper!” Conclusions: • The nucleus is small • The nucleus is dense • The nucleus is positively charged

34. Top of worksheet

35. Bohr Model of Atom aka “planetary model” • Electrons assume only certain orbitsaround the nucleus. These orbits are stable and called "stationary" orbits. • 2. Each orbit has an energy level associated with it. For example the orbit closest to the nucleus has an energy E1, the next closest E2 and so on. • 3. Light is emitted when an electron jumps from a higher orbit to a lower orbit and absorbed when it jumps from a lower to higher orbit. • 4. Energy of light emitted is the difference between the two orbit energies.

36. Bohr Model of Atom aka “planetary model” 1st shell  2 e- 2nd shell  8 e- 3rd shell  8 e- 4th shell  18 e- 5th shell  18 e- 6th shell  32 e- 7th shell  32 e-

37. Electron Cloud • More accurate • e- don’t travel in simple, specific orbits • e- travel around nucleus in random, unpredictable orbits at superfast speeds • Can’t tell exactly where they are, but they’re somewhere in the “e- cloud”

38. Orbitals Electrons can be in 4 types of orbitals within an energy level… Named s, p, d, or f Don’t worry about them for now…we’ll talk more about them later.

39. Bell Work 11/27/12 • Discovered the nucleus • Planetary model of atom • Plum pudding model of atom • Discovered most of the atom is empty space • Cathode rays • Discovered electron • Gold foil experiment • W5SAYBoS

40. Today you are going to…take notes on the parts of an atom & isotopes. So you can…explain the basic structure of an atom, which will help you to predict bonds in the future. You’ll know you’ve got it when you can • Identify all parts of an atom, their relative masses, charges, and location. (complete chart) • Determine the mass of an isotope

41. Atom – smallest particle of an element that retains the chemical properties of that element. Composed of: protons neutrons electrons

42. Subatomic Particles Protons Positive charge In nucleus (tiny, dense, center of atom) Mass of 1 amu (atomic mass unit) Neutrons Neutral (no charge) In nucleus Mass of 1 amu Electrons Negative charge In “electron cloud” around nucleus (“orbit” nucleus) Very little mass (about 1/2000 P, or 0.0006 amu)

43. Atomic Particles

44. Force in the Nucleus • Two protons extremely close to each other attract • (indirect effect of strong nuclear force, the strongest force in the universe!) • Over 100 protons can exist together in a nucleus! • Strong nuclear force has same effect on neutrons.

45. “e-” “no” “p+” cathode rays + charge Determines what element atom is Protons Electron no charge - charge very little mass orbits nucleus subatomic particles found in atom charged about same mass in nucleus Neutrons

46. Understanding Isotopes

47. Atomic Number • Number of protons in an atom • Tells which element atom is • Atoms of the same element ALWAYS have the same number of protons. • Above atom on periodic table

48. What subatomic particles have the most mass? • What subatomic particle has hardly any mass? • Therefore, an atom’s mass depends on how many ___ and ___ it has. • All atoms of the same element have the same ____ ____, which means they have the same number of _____. • Do all atoms of the same element have the same mass? • What must be different about these atoms? • Atoms of the same element with a different number of neutrons are called isotopes.

49. Isotopes Elements occur in nature as mixtures of isotopes. Isotopes are atoms of the same element that differ in the number of neutrons Isotopes are named by their mass number

50. Isotopes atoms of same element with different number of neutrons and, therefore, different masses