2. SC3 Students will use the modern atomic theory to explain the characteristics of atoms.
a. Discriminate between the relative size, charge, and position of protons, neutrons, and electrons in the atom.
b. Use the orbital configuration of neutral atoms to explain its effect on the atom’s chemical properties.
c. Explain the relationship of the proton number to the element’s identity.
d. Explain the relationship of isotopes to the relative abundance of atoms of a particular element.
e. Relate light emission and the movement of electrons to element identification.

3. This will be our FOCUS
Matter
Mixture
Substance
Element
Compound

4. What is an Element?
One of the ~116 known “Pure”, un-cutable substances….that still retain the properties of that substance.

5. What is an Atom?
Smallest piece of matter that still retains the properties of that matter.
What are they composed of?

6. Timeline
Bohr Model- electrons are found only in specific circular paths, or orbits, around the nucleus.
Electron Cloud Model: Probable locations of electrons.
MODERN:
Quantum Mechanical Model: Mathematical model describing the behavior of electrons and energy of electrons in various locations around the nucleus.

7. Subatomic Particles Nucleus Atomic Structure Protons Neutrons
Electrons
Nucleus

8. Atomic Structure

9. What makes one element different from another element?
Number of protons.
Atomic Structure

10. Atomic Structure
Rutherford’s Gold Foil experiment led to the discovery of a positive nucleus.

11. Protons Positive Charge
Atomic Structure
Protons
Positive Charge
The number of protons determines which element it is.
All elements have different numbers of protons
1 amu
Composed of quarks

12. Neutron Neural charge Located in the nucleus 1 amu Composed of quarks
Atomic Structure
Neutron
Neural charge
Located in the nucleus
1 amu
Composed of quarks

13. Electrons Smallest subatomic particle. 1/1800 the mass of a proton.
Atomic Structure
Electrons
Smallest subatomic particle.
1/1800 the mass of a proton.
Orbit nucleus.
Negative Charge

14. Electrons are found in different levels around the nucleus.
Atomic Structure
Electrons are found in different levels around the nucleus.
These are called Energy Levels or shells.
Each energy level also has “sublevels” or orbitals

15. Atomic Structure

16. Electrons are found in the surrounding the nucleus.
Atomic Structure
Electrons are found in the
Electron cloud
surrounding the nucleus.

17. Each Energy Level Can Hold A Certain Number of Electrons!
Atomic Structure
Each Energy Level Can Hold A Certain Number of Electrons!
Only TWO on the first level!

18. 2n2 Each Energy Level Can Hold A Certain Numbers of Electrons!
Atomic Structure
Different atoms have different numbers of electrons!
Each Energy Level Can Hold A Certain Numbers of Electrons!
Eight on the 2nd
2n2

19. Atomic Structure

20. Atomic Structure

21. 1 Atomic Mass Sum of Protons & Neutrons Atomic Number
Atomic Structure
Atomic Number
Number of Protons 1 H
Atomic Mass
Sum of Protons & Neutrons 1
The # of Protons determines the identity of an element. All elements have different number of protons.

22. How can I find out how many electrons an atom has?
Atom= neutral
So, the number of protons = electrons.
Atomic number tells you the number of protons
So, it also tells you the number of electrons!
Atomic Structure

23. Practice with a friend…………

24. Quantum Mechanical Model
Based on quantum theory, which says matter also has properties associated with waves.
According to quantum theory, it’s impossible to know the exact position and momentum of an electron at the same time. This is known as the Uncertainty Principle.
This model of the atom uses complex shapes of orbitals (sometimes called electron clouds)
Orbitals: volumes of space in which there is likely to be an electron.
So, this model is based on probability rather than certainty.

25. Atomic Orbitals
An atomic orbital is a region of space in which there is a high probability of finding an electron.
Energy levels of electrons are labeld by principal quantum numbers (n).
Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found.
Different orbitals have different shapes.

26. Quantum Numbers n, l, m, s Describing electron locations
1st-Principle Quantum # = n
Which energy level the e- is in.
n= 1-7 (there are only 7 energy levels)
Max # formula= 2n2
the larger the value of n, the farther away from the nucleus and the higher the energy of the electron.

27. # of sublevels 2nd quantum number= l Describes the shape (orbital)
Shapes: s, p, d, f
Each shape “sublevel” can only have 2 electrons.
Max electrons in each sublevel:
s=(1x2)2, p=(3x2)6, d=(5x2)10, f=(7x2)14
# of sublevels

28. s & p

29. # of sublevels (shapes)
S (1), p (3), d (5)
# of sublevels (shapes)

30. F (7)

31. Describes orientation in space x, y, z
3rd quantum number= m
Describes orientation in space
x, y, z
4th quantum number= s
Describes the spin of the e in the orbital
Clock or counterclock

34. Brain Break
Clip

35. Orbital Filling Diagrams (3 rules)
Aufbau Principle: e- occupy orbitals of the lowest energy first.
p.133 text

36. Orbital Filling Diagrams
Hund’s Rule: one electron in each orbital, then electrons pair up with opposite spins.
Pauli Exclusion Principal: An orbital may have no more than 2 electrons. 2 e- cannot have the same spin in the same orbital.

37. Practice:
H, C, Na, S, Ar, K.

38. Blocks and Sublevels
We can use the periodic table to predict which sublevel is being filled by a particular element.

40. Electron Configuration Notation

41. Practice: Write the electron configuration notation.
Name Atomic Number Electron Configuration
Oxygen 8 1s2 2s22p4
Aluminum 13 1s2 2s22p63s23p1
Chlorine s2 2s22p63s23p5

43. Electrons and Light Emission
When atoms absorb energy, electrons move into higher energy levels (excited state).
When the return to their ground state, the lose energy by emitting light.
The light emitted is a mixture of a specific frequencies.

44. A quantum of energy is the amount of energy required to move an electron from on energy level to another energy level.
The higher the ground state, the less energy it take to move to a higher energy level.

45. Electrons & Light Emission
Each frequency is a different color.
When the frequencies are passed through a prism, the colors are separated & an atomic emission spectrum is created for that element.
Larger “jump”- more energy-more towards the blue side
Smaller “jump”- less energy-more towards the red side

46. The flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic color the salt turns the flame of a bunsen burner

47. Isotopes

48. Isotopes
Isotopes are atoms that have the same number of protons and differ only in the number of neutrons.
Most isotopes are stable but radioactive isotopes are unstable and break down into more stable forms by emitting particles and energy (radiation).
Radiation can be detected, so radioactive isotopes are useful as labels in scientific research and medical diagnostic procedures.

50. Let’s Do some practice problems 

52. How do you find this number?

53. Calculating Average Atomic Mass
Percent(%) abundance of isotopes
Weighted average= Mass of each isotope x % abundance of that element

54. Atomic Mass of Magnesium
Isotopes Mass of Isotope Abundance
24Mg = 24.0 amu % = ______
25Mg = amu % = ______
26Mg = amu % = ______
Atomic mass (average mass) Mg = 24.3 amu Mg
24.3

55. Practice
Gallium is a metallic element found in small lasers used in compact disc players. In a sample of gallium, there is 60.2% of gallium-69 (68.9 amu) atoms and 39.8% of gallium-71 (70.9 amu) atoms. What is the avg. atomic mass of gallium?

56. Practice
A sample of boron consists of 10B (mass 10.0 amu) and 11B (mass 11.0 amu). If the average atomic mass of B is 10.8 amu, what is the % abundance of each boron isotope?

57. Counting Atoms
The Mole

58. The Mole
For a given molecule (atom), one mole is a mass (in grams) whose number is equal to the atomic mass of the molecule (atom)
What is the Mole?
A counting number (like a dozen)
Avogadro’s number (NA)
1 mol = 6.02  1023 items

59. The Mole Avogadro's number
1 mole of molecules has a mass equal to the molecular weight in grams.
A mole of carbon-12 atoms has a mass of just 12 g.
How many Atoms is that???
1 mole = x 1023 atoms
Amedeo Avogadro ( )
Avogadro's number

60. Molar Mass Mass of 1 mole of an element or compound.
Atomic mass tells the...
atomic mass units per atom (amu)
grams per mole (g/mol)
1 atom of C = amu
1 mol of C = g
Round to 2 decimal places

61. Molar Mass Examples lithium aluminum zinc 6.94 g/mol 26.98 g/mol

62. Molar Conversion Examples
How many grams of iron are in 2.25 mol of iron?
2.25 mol Fe
55.85 g Fe
1 mol Fe
= 126 g Fe

63. Molar Conversion Examples
How many moles of calcium are in 5.0 g of calcium?
5.0 g Ca
1 mol Ca
40.08 g Ca
= 0.12 mol Ca

64. 1 mole of Na is the number of atoms in 22.9898g
Examples
1 mole of Na is the number of atoms in g
g is the molar mass
1 mole H2O is the number of molecules in g H2O
1 mole H2 is the number of molecules in g H2.
Practice:
How many atoms are in 1 mol of H?
What is the mass of 1 mol of H?
How many atoms are in 2 mole of H?
What is the mass of 2 mol of H?

65. More Practice:
Convert 589 g of Au to moles.
Convert 344 grams of Fe to moles.
What is the mass of 3 moles of KOH?

66. Mole Day is October 23rd!