I. The Periodic TableA. Chart giving data about the known elements

B. History1. Dmitri Mendeleev given credit for an early version of periodic table

In 1869

2. Recognized recurring pattern of element properties with mass increase

3. Discovery of Elements in the Periodic Table

C. Information on a Periodic Table

1. Name and/or Symbol for each element

a. Most elemental symbols are abbreviations of their name

b. Some symbols come from older names for the element

i. Fe for Iron comes from the older name Ferrum

ii. Au for Gold come from the older name Aurum

2. Atomic Number = number of protons in the element (electrons if neutral)

3. General Properties

a. Metal (copper)

i. Conductive, malleable, ductile, and lustrous

ii. Lose electrons to form cations

b. Nonmetal (oxygen)

i. Lack the metallic properties

ii. Gain electrons to become anions

4. Groups or Families are arranged in columns

a. Similar reactivities

b. Group I = Alkali metals = reactive and easily form +1 cations

c. Group VIII = Noble Gases = unreactive gases

5. Main Group and Transition Elements

6. Families or Groups on the Periodic Table

a. Group 1A = Alkali Metals—reactive metals

b. Group 2A = Alkaline Earth Metals—fairly reactive metals

c. Group 7A = Halogens—very reactive nonmetals

d. Group 8A = Noble Gases—almost completely unreactive

7. Ions and the Periodic Table

a. Main Group Metals tend to lose electrons and form cations

b. Main Group Nonmetals tend to gain electrons and form anions

c. Group 1A forms +1 cations

d. Group 2A forms +2 cations

e. Group 3A metal (Aluminum) forms +3 cation

f. Group 5A (Nitrogen) form -3 anion

g. Group 6A nonmetals form -2 anions

h. Group 7A nonmetals form -1 anions

Achieve Noble GasElectron #’s

II. Atomic MassesA. Mass spectrometers and atomic masses

1. Carbon is used as the standard for atomic masses

2. In 1961, 12C was assigned a mass of exactly 12 atomic mass units (amu)

3. A mass spectrometer can compare other elements or isotopes to 12C

4. 13C is found to be 1.0836129 times as massive as 12C

5. Mass of 13C = (1.0836129)(12 amu) = 13.003355 amu

B. Average Atomic Masses

1. Why isn’t the mass of Carbon listed at exactly 12 on the periodic table?

2. Natural carbon: 12C(98.89%), 13C(1.11%), and 14C (negligible)

a. Avg. Mass = (0.9889)(12 amu) + (0.0111)(13.0034 amu) = 12.01 amu

b. No individual atoms have this mass

c. On average, all natural carbon atoms have this mass

d. 12.01 amu is the correct value to use for calculations involving carbon

3. Example: What is avg. mass of Cu?

69.17% 63Cu (62.9396 amu) and 30.83% 65Cu (64.9278 amu)

4. Calculate the Mass (in amu) of 75 atoms of Al

a. Determine the mass of 1 Al atom: 1 atom of Al = 26.98 amu

b. Use the relationship as a conversion factor

amu 2024 atom Al 1amu 26.98

x atoms Al 75

69.17

30.83

III. The MoleA. We use a package for atoms and molecules called a mole

1. A mole =

a. the number of Carbon atoms in 12 g of 12C

b. 6.022 x 1023 units = Avogadro’s Number

c. The amount of an element equal to its atomic mass

3. 1 mole of natural C atoms weighs 12.01 g and has 6.02 x 1023 atoms

4. 1 mole of He atoms weighs 4.003 g and has 6.02 x 1023 atoms

5. 1 mole of Al atoms weighs 26.98 g and has 6.02 x 1023 atoms

6. Example: What is the mass of 6 Americium atoms?

B. Calculating moles, mass, and atoms

1. Example: # atom / moles in 10g Al

Cu

Al

FeS

I2

Hg

g 10 x 42.2mol

g 243

atoms 10 x 6.022

mol 1atoms Am 6 -21

23

Al atoms 10 x 2.23Al mol 1

Al atoms 10 x 6.022 Al mol 0.371

Al mol 0.371g 26.98

Al mol 1Al g 10.0

2323

C. A mole is the chemists “dozen”

1. A dozen marbles and a dozen peas both have 12

2. A dozen marbles might weigh 100 grams

3. A dozen peas might weigh only 15 grams

4. Example: 5.68 mg Si = ? atoms Si

Si atoms 10 x 22.1Si mol 1

Si atoms 10 x 6.022 Si mol 10 x 02.2

Si mol 10 x 02.2g 28.09

Si mol 1Si g 10 x 68.5

Si g 10 x 68.5mg 1000

g 1mg 68.5

2023

4-

4-3-

3-