1. Elements are made of atoms = the smallest particle that has all the characteristics of the element

2. How Small is an Atom? A copper penny contains 2.4 x 1022 atoms
Earth’s population is approx. 7 x 109
A scanning tunneling microscope makes it possible to see individual atoms
TED
Ted video 5:27

3. Scanning Tunneling Microscope

4. Atom Image

5. Subatomic Particles
Mass of atom is generally protons + neutrons, majority of mass is in nucleus
Mass of proton = 1
Mass of neutron = 1
Mass of electron = 1/2000
(mass of H proton = 1 = is standard)

6. Subatomic Particles Subatomic Particle Charge Location Proton Neutron
Electron

7. Atoms are neutral…
Why?

9. Distinguishing Between Atoms

10. Atomic Number (Z) Found on the periodic table
Is equal to the number of protons
Each element has its own atomic #
# protons = # electrons

11. Average Atomic Mass Also found on the periodic table
Is the average mass of all of the atoms of that element
Mass number = (A) actual mass of one atom
Mass number = protons + neutrons

12. When written in this format… 12 is the mass #
Carbon-12?
When written in this format…
12 is the mass #

13. Practice with a Partner
Atom
Symbol
Atomic #
Aver Atomic Mass
Mass # #
protons
# neutrons
# electrons
Lithium 7
Boron 9
Carbon 12
Nitrogen 14
Oxygen 16
Helium 4
Sodium 23

14. Isotopes Atoms of the same element that have different masses
Have different masses because they have different numbers of neutrons
# protons always the same

15. Example Carbon isotopes Might also be written C-12, C-13, C-14 Or

16. Nuclear Formulas
Used to write isotopes…

17. Isotopes How are isotopes similar? How do they differ?
Isotopes are chemically alike b/c they have identical numbers of protons & electrons

18. Average Atomic Mass How is it calculated?
Based on the relative abundance of the naturally occurring isotopes of the element
Each isotope has a fixed mass and a natural % abundance

19. Question
With the following information, calculate the average atomic mass of chlorine:
76% of chlorine isotopes found naturally have a mass of 35
24% of chlorine isotopes found naturally have a mass of 37

20. How did you find the answer?

21. PROJECT

22. Warm Up 1/15/2014 P P
Calculate average atomic mass given the following information:
Carbon-12 is found naturally 98.89% of the time
Carbon-13 is found naturally 1.11% of the time

23. Warm Up 1/16/2014
Write the procedure for determining average atomic mass (paragraph format, complete sentences).
Quiz tomorrow—cumulative
Homework tonight

24. Atomic Theories Democritus John Dalton JJ Thomson Ernest Rutherford
Niels Bohr
Schrodinger

25. “Atom” & Democritus 400 BC Called nature’s basic particle an atom
Atom (Greek) means uncuttable or indivisible
No experimental evidence

26. Dalton’s Atomic Theory (1808)
All matter is composed of tiny indivisible particles called atoms
Atoms of the same element are identical
Atoms of different elements can physically mix together or can chemically combine with one another in simple whole number ratios to form compounds
Chemical reactions occur when atoms (in compounds) are separated, joined, or rearranged

27. Dalton’s Atomic Theory
Much of Dalton’s theory is accepted …except ?
Except that atoms are indivisible AND that all atoms of an element are identical

28. Thomson & Plum Pudding Model
1897
Discovered the electron
His model proposed that negatively charged particles were randomly distributed within a pudding of positively charged particles

29. Rutherford & The Gold Foil
1909
Discovered the atom’s nucleus
He bombarded a thin, gold foil with fast moving alpha particles (p 72-73)

31. Rutherford & The Gold Foil
A small amount of particles were deflected by the tiny nucleus; most of the particles passed on through
He concluded the volume of the atom was mostly empty space

32. Bohr’s Atomic Model
1915
Electrons organized in energy levels or shells around a nucleus of protons and neutrons
A “planetary” model—not entirely correct

33. The Electron Cloud & Schrodinger
Is a probability model
Describes a cloud like region where the electron is likely to be
Based on mathematical equation

35. Project Time

36. A Closer Look…the Bohr Model
Video

37. Bohr’s Model of the Atom
Scientists found that when an electric current is passed through a glass tube that contains hydrogen gas, the tube emits light
When this light is passed through a prism, four narrow bands of bright light are observed against a black background
This is hydrogen’s line emission spectrum
Bands are at specific wavelengths, which are unique to each element

38. Niels Bohr
Niels Bohr proposed a model for the hydrogen atom that explained the spectrum of the hydrogen atom.
The Bohr model was based on the following assumptions:

39. Bohr’s Model of the Hydrogen Atom
Electrons are arranged in concentric circular paths or orbits around the nucleus
Electrons in a particular path have a fixed energy
The energy of the electron in an orbit is proportional to its distance from the nucleus. The further the electron is from the nucleus, the more energy it has.
An electron can either gain or lose energy inside this orbit, electrons can move up or down to another orbit

40. Continued…
A quantum of energy = is the amount of energy required to move an electron from its present energy level to the next higher one
Light is absorbed when an electron jumps to a higher energy orbit and emitted when an electron falls into a lower energy orbit

41. Continued…
The energy of the light emitted or absorbed is exactly equal to the difference between the energies of the orbits
The energy given off is electromagnetic radiation
Is given off as photons (particle of light with no mass)

42. Continued… Lowest energy state of atom = ground state
Higher energy state of atom = excited state
Neon signs—excited neon atoms emit light when falling back to the ground state

43. Reminder…Quiz tomorrow
Project Time
Reminder…Quiz tomorrow

44. Warm Up 1/17/2014
How did Bohr’s model of the atom differ from Schrodinger’s?

45. Modern Atomic Theory

46. Electron Cloud Model AKA quantum mechanical model
Clouds of probability = where electrons are most likely to be
Electrons are located in orbitals (not orbits)

47. Electron Cloud Model 4 types of orbitals: s, p, d, f
Each orbital can only hold 2 electrons

48. Warm Up 1/21/2014
Construct a table to compare subatomic particles.

49. Warm Up 1/24/2014
Create a Venn diagram to compare the Bohr model to the electron cloud model.
Homework DUE
Quiz today

50. Warm Up 1/27/2014 Given an isotope for fluorine, fluorine-19…
What is Z?
What is A?

51. Quizzes
Dropped one question
2nd block 84
3rd block 86

52. What are ions? Why would ions form?
Atoms with a charge
When they gain, lose, or share electrons
But…why would they do this?

53. What is the Octet Rule?
Says that atoms tend to gain, lose or share electrons so as to have eight electrons in their outer electron shell…
More specifically, the number of electrons needed to fill the s and p sublevels of that energy level

54. Practice

55. Nuclear Chemistry

56. How Atoms Combine
Section 3.2

57. Chemical Properties Chemical properties = how reactive an atom is
Does it like to combine with other atoms or is it stable alone?
Which groups on the periodic table are reactive?
Which groups are stable?

58. Compounds
A substance that is composed of atoms of 2 or more different elements that are chemically combined
Example = NaCl
Why do these two atoms like to combine?
(draw)

59. Types of Bonds Ionic bonds—when atoms lose or gain electrons
Example = _____________
Covalent bonds—when atoms share electrons
Example = ______________
(draw)

60. Compounds
Atoms want their outer energy level filled with electrons, in most cases this is 8 electrons
Which groups on the periodic table would you predict would commonly form bonds together?
Class Bonding Activity

61. Complete Section Assessment 3.1 #1-5 on page 59
Warm Up 8/30/12
Complete Section Assessment 3.1
#1-5 on page 59

62. Group Assignment
Chemical Reactivity worksheet

63. Independent Notebook Assignment
Vocabulary section 3.2 (page 60)

64. Independent Assignment
Create a poster—to display a large drawing of an atom…the element will be assigned to you.
Format: see example
Grading: based on neatness & accuracy.

65. Element Assignment H Ne He Na Li Mg Be Al B Si C P N S O Cl F Ar

66. Warm Up 8/31/12 What group # is chlorine in? What is its symbol?
List everything that you can learn about chlorine based its location in the periodic table. Include what other elements it might bond with.

67. Agenda
Quiz
Project Presentations