Periodic Law

1. Chapter 5

2. The Periodic Table

3. History of Periodic Table
1860
More than 60 elements had been discovered
No accurate method to determine atomic mass or
the number of atoms of element in compounds
Different chemists used different values for the
same elements
September of 1860
First International Congress of Chemists
Cannizzaro (Italian) presented method for
measuring atomic masses of atoms
Enabled chemists to agree on standard values for
atomic mass

4. History Continued…
Mendeleev
Russian Chemist
Wanted to organize elements
according to properties
Created first periodic table
based on similarities
Left many spaces due to his
process of organization

5. History Continued…
Moseley
Worked with Rutherford
Discovered a previously
unrecognized pattern
Work led to modern
definition of atomic
number and this is the
basis for organization of
table
Consistent with
Mendeleev’s ordering of
table

6. Periodic Law
Based on Mendeleev’s principle of
chemical periodicity
The physical and chemical properties
of the elements are periodic functions
of their atomic numbers.

7. Periodic Law
In simple terms:
When the elements are arranged in order of
increasing atomic number, elements with similar
properties appear at regular intervals

8. Modern Periodic Table
Noble Gases
First was discovered in
1868
Helium
Discovered as a
component of the sun

9. Modern Periodic Table
Lanthanides
The 14 elements with
atomic numbers from 58
(Cerium) to 71
(Lutetium)
Belong to the
6
th
period

10. Modern Periodic Table
Actinides
The 14 elements with
atomic numbers 90
(Thorium) to 103
(Lawrencium)
Belong to the 7th
period

11. 5.2: Electron
Configuration
& The Periodic Table
Periods
Horizontal rows on the periodic table
Identifies energy level of element

12. Electron Configuration and
Periodic Table
Groups/Families
Vertical columns on table
Identifies number of valence electrons

13. Group 1
Group 1 (Alkali Metals)
Silvery appearance
Soft enough to cut with
a knife
Extremely reactive
Not found in nature as
free elements
Melt at low
temperatures

14. Group 2
Alkaline-Earth Metals
Harder
Denser
Stronger
Slightly less reactive
Not found in nature as
free elements

15. Groups 3 - 12
Transition Elements
Good conductors of
electricity
High luster
Some do not form
compounds easily
Exist in nature as free
elements

16. Group 17
Halogens
React with most metals
to form salts
7 electrons in outer shell
Exist at room
temperature in all three
states of matter

17. Group 18
Noble Gases
Inert gases
Relatively nonreactive
Have a complete
valence shell
Low boiling points
All are gases at room
temperature

18. Periodic Properties
Arranged on periodic table according to
atomic number
However, that isn’t all!

19. Periodic Properties
Atomic Radii
Ionization Energy
Electron Affinity
Ionic Radii
Electronegativity

20. Cited Sources:
Photo of Mendeleev
http://www.bluffton.edu/~bergerd/nsc_111/science2.html
Photo of Moseley
http://physics.ucsc.edu/groups/condensed/moseley/
Lanthanide series
http://www.ggg.gl/Rare-Earth-Elements/Rare-Earth-Elements.htm
Noble gases
http://brotiman.glogster.com/noble-gases/
Actinide series
https://www.llnl.gov/news/newsreleases/2007/NR-07-06-03.html
Halogen Group
http://www.chem4kids.com/files/elem_halogen.html
Periods
http://www.chem4kids.com/files/elem_pertable.html
Groups/Families
http://www.dummies.com/how-to/content/the-periodic-table-families-and-periods.html
Alkali Metals
http://www.learner.org/interactives/periodic/groups2.html

21. Cited Sources Continued….
Alkaline-Earth Metals
http://www.chem4kids.com/files/elem_alkalineearth.html
Transition Elements
http://www.radiantchuaminhuiace.blogspot.com/
Noble Gases
http://www.daviddarling.info/encyclopedia/N/noble_gas.html
Periodic Table
http://en.loadtr.com/Periodic_Table_could_have-438617.htm
Periodic Table Video
http://
player.discoveryeducation.com/index.cfm?guidAssetId=DFDF8F8A-C1F1-49E1-ADE5-59E340A4D519&blnFromSearch=1&productcode=US