1. Atomic Structure
3.1

2. Atomic History
In 400 BC a Greek Philosopher named Democritus suggested the universe was made of invisible units called atoms.

4. 1800’s John Dalton’s Theory (Still Accepted)
Every element is made of tiny, unique particles called atoms
Atoms of different elements can join to form molecules.

6. John Dalton’s Theory- Disproved
Atoms are the smallest particles and cannot be subdivided.
Atoms of the same element are exactly alike in mass

7. JJ Thomson
Credited with discovering negative charged particles called electrons.

10. Rutherford Credited with discovering the nucleus.
Also concluded that atoms are mostly empty space.

14. Further Research Finding
Later on, the discovery of protons and neutrons were discovered in the nucleus.
And it was later concluded that all atoms are neutral in charge.
The number of protons and electrons in any atom are always equal.

15. Niels Bohr
Suggested that electrons move around atoms in set paths around the nucleus.
He said each path is an energy level

19. Today’s Theory
It has been determined that it is impossible to pinpoint an electron’s exact position due to its tremendous speed.
Electrons do not move around in definite paths.

20. Today’s Theory
Electrons are found in orbitals within energy levels. (s, p, d, and f )
a region in an atom where there is a high probability of finding electrons.

22. Today’s Theory
Electrons are now viewed as waves vibrating on a string rather than simple particles.
Wave-Particle Duality Theory

24. What are atoms?
The smallest part of an element that still has the element’s properties.

25. Parts of an atom
Nucleus
Proton
Neutron
Electron
Subatomic particles

26. Nucleus center of an atom positively charged
makes up 99.9% of the atom’s mass
contains protons and neutrons

27. Protons Charge (+) Mass is equal to 1 atomic mass unit (amu)
Found in the nucleus
Identifies the element/atom

28. Neutrons Charge (0) – neutral Mass is equal to 1amu
Found in the nucleus
Helps determine mass

29. Electrons Charge is negative (-) Mass is equal to 0 amu
Found outside the nucleus, in the electron cloud

30. Energy levels 1st level holds up to 2 e- 2nd level holds up to 8 e-
3rd level holds up to 8 or 18 e-
4th level holds up to 8, 18, or 32 e-
Outer Level holds up to 8 e-
(called valence electrons)

31. Valence Electron
The number of electrons in the outermost electron shell.
Most important

32. A Guided Tour of the Periodic Table
3.2

34. Periodic Law
Properties of elements tend to change in a regular pattern when elements are arranged in order of increasing atomic number.

35. Periodic Table is set up by increasing atomic number.
Periodic Law
Periodic Table is set up by increasing atomic number.
Atomic Number is the # of protons in the atom.

36. Average Atomic Mass

37. tells you number of protons Never Changes for an atom.
Atomic Number
tells you number of protons
Never Changes for an atom.
Appears as a whole # on the periodic table.
No two elements can have same atomic #.

38. Atomic Number
Atomic
Number
# of
protons

39. Total number of protons plus neutrons in the nucleus of a single atom.
Mass Number
The mass of an atom
Total number of protons plus neutrons in the nucleus of a single atom.
Atoms of the same element won’t always have the same mass number

40. Mass Number
# of
neutrons
Mass #
# of
protons

41. So they also have different mass numbers.
Isotopes
Any atoms having the same number of protons but different number of neutrons.
So they also have different mass numbers.

43. Average mass of all known isotopes for an element
Average Atomic Mass
Average mass of all known isotopes for an element
Found on the periodic table as a number with a decimal

44. All atoms have the same number of protons and electrons.
Atom’s Charge
They are neutral.
All atoms have the same number of protons and electrons.
Charges cancel each other out.

45. Form when atoms lose or gain electrons.
Ions
Charged particles.
Form when atoms lose or gain electrons.
They do this so the ions have a full outer shell
Two Types.

46. Positively charged ions. Form when atoms lose electrons. Metals
Cations
Positively charged ions.
Form when atoms lose electrons.
Metals
Left side of table

47. # of protons greater than # of electrons More (+) than (-)
Cations
# of protons greater than # of electrons
More (+) than (-)

48. Na Atom
Na+ Cation

49. Negatively charged ions. Form when atoms gain electrons. Nonmetals
Anions
Negatively charged ions.
Form when atoms gain electrons.
Nonmetals
Right side of table

50. # of protons less than # of electrons More (-) than (+)
Anions
# of protons less than # of electrons
More (-) than (+)

51. Cl- Anion
Cl atom

52. Quantifying atoms or ions+1
Protons = 3
Neutrons = 7-3 = 4
Electrons = 3
Electrons = 3 -1 = 2

53. Families of Elements
3.3

54. Periodic Table Periods -a horizontal row of elements.
-Tells you the electrons energy level.

55. Periodic Table Groups (families) -a vertical column of elements.
-Tells us the # of valence electrons and the elements’ chemical properties.

56. Semiconductors/metalloids
Types of Elements
Metals
Nonmetals
Semiconductors/metalloids

57. Inner Transition Metals
Alkali Metals
Nobel Gases
Non Metals
Alkaline Earth Metals
Metalloids
Halogens
Other Metals
Transition Metals
Inner Transition Metals

58. Alkali Metals Group 1 Most reactive metals one valence e-
Found as compounds (salts) and not elements due to reactivity.
As elements they are soft metals and good conductors.

59. fun

61. Alkaline-earth Metals Group 2
Less reactive than Alkali
They are also more commonly found as compounds
2 most common are Ca and Mg.

63. Transition Metals Groups 3-12
Less reactive than groups 1 and 2
Good conductors

65. Transition Metals All solids with the exception of mercury
Valuable metals (Ag, Au, Pt, Cu, Ni, Fe, Co)

67. Non Metals Are not able to conduct electricity or heat very well.
Found in groups 13-18, with the exception of hydrogen

68. Carbon Found as an element (coal, diamond, graphite)
Found in millions of different compounds
Called Organic Compounds

69. HYDROGEN It is a gas/nonmetal A very explosive gas.
It is located in group one because it has one valence electron
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70. Oxygen is the most common element found on Earth
Oxygen and Nitrogen
Oxygen is the most common element found on Earth
Nitrogen most common gas found in the atmosphere

71. Halogens Group 17 Most reactive nonmetals Form salts with group 1
Used to kill bacteria
Bromine only liquid nonmetal

73. Noble Gases Group 18 Stable and not reactive. (inert)
Don’t form compounds.
They have a full valence shell.

75. Metalloids (Semiconductors)
7 elements on the step
Properties of both metals and non- metals.
Silicon the most familiar (computer chips)

76. Inner Transition Metals
Two rows at the bottom
Some are Radioactive ex. Uranium
93 and greater are all manmade

78. Moles
3.4

79. Counting Units We buy things by the dozen. One dozen = 12 items
We use the unit mole to count things in chemistry

80. Moles
the SI base unit that describes the amount of a substance.

82. Avogadro’s Constant
Represents the number of particles in one mole of a substance.
The number is 6.02 x particles, atoms, or molecules

84. Moles Used for counting with really tiny atoms
One mole represents the atomic mass of an element.

85. Molar Mass The mass in grams of 1 mol of a substance.
Using the periodic chart you can determine the molar mass of any element or compound.

87. Molar Mass Example
So how many grams in two moles of Ca?

88. Solution The molar mass of Ca is 40 g/mol. 2 moles x 40 grams = 80 g

89. Mole Problems
You can determine how many moles of a substance you have if you know the mass of the substance.

90. Example Problem
If you have 92 grams of Na how many moles would you have?

91. Solution
MM of Na is 23 g/mole
92 g x 1 mole = 4.0 moles
23 g