1. The Periodic Table
2. Why make a table
a. Search for order
b. Organized knowledge more useful
c. Predictive
3. Difficulties
a. Only 3/5's of elements known’
b. Knowledge incomplete
c. Matter is tangible, numbers abstract
d. No evidence for numerical patterns
4. Döbereiner’s Triads
a. An apothecary
b. Similar properties
c. Varied by atomic mass
d. Center element average of other two
e. No global picture
f. Not predictive
5. Newland
a. Fought w/Garibaldi, the sugar chemist
b. Arranged by mass with new row on repetition
c. Properties repeated every 8th element
d. Called them octaves
i. Discovery ridiculed
ii. Music not part of chemistry
6. Meyer
a. Professor of chemistry
b. Compared reactivity and volume mass
c. Found octave pattern for first eighteen elements
d. 18 element pattern for remaining elements
e. First evidence of pattern in atoms
7. Line Spectrum Analysis
a. Developed in 1850's
b. Each element has unique line spectrum
c. Large number of new elements identified
8. Mendeleev
a. Chemist to Czar
b. Believed rows could vary in size
c. Mass fundamental property
d. Ordered elements by mass and properties
i. Properties most important
e. Mass and properties did not match for some
i. Assumed mass measured wrong
f. First to accept gaps
i. Used to predict properties of undiscovered elements
g. Columns have similar properties
h. Rows change gradually between extremes
9. Periodic Law
a. Properties of elements are a periodic function of atomic mass
10. Moseley
a. Used x-ray diffraction to count protons
b. Revised table using Z
i. Ordering unambiguous
ii. Clearly show missing elements
iii. Pointed to existence of noble gases
11. Revised Periodic Law
a. Properties are a periodic function of atomic number
12. Using the Periodic Table
13. Basis for the Table
a. Number of Protons (identity)
b. Energy Level (row)
c. Electron Configuration (column)
14. Outer Level
a. Only “s” and “p” orbitals
b. Fill in order of energy
c. Each block adds 1 electron
d. Elements in group have same configuration
15. Atomic Number
a. Number of protons
b. Determines identity
16. Period
a. Row in table
b. All elements have same number of energy levels
c. Valence electrons increase left to right
d. Row number is number of outer level
17. Group
a. Column in table
b. Same number of valence electrons
c. Configuration of outer level same
d. Properties similar
18. Stability
a. 8 electrons in outer level
b. Orbital full
c. Orbital half full
19. Classification: Metals
a. 3 or fewer valence electrons
b. Lose electrons in compounds
c. Conduct well
d. Hard
e. Shiny
f. Solids
20. Classification: Non-metals
a. 4 or more valence electrons
b. Gain or share electrons in compounds
c. Gases or brittle solids
d. Insulators
21. Classification: Metalloids
a. Share properties of metals and non-metals
b. Separate metals and non-metals in periodic table
c. Semiconductors
22. Semiconductors
a. Current is flow of electrons
b. Pure metalloid (Si) holds electrons tightly
c. Add impurities current flows
23. N type
a. Add 5 valence electron atoms
b. Only 4 pair with Si
c. Extra electrons free to move
24. P type
a. Add 3 valence electron atoms
b. One Si electron not paired
c. Creates “hole” for electron to fill
25. Diodes and Transistors
a. Replaced vacuum tubes
b. Current only flows from N to P
c. IC chips