1. “The Periodic Table2”
NOTES #6

2. Organizing the Elements
A few elements have been known for thousands of years - since ancient times
As more were discovered, chemists realized they needed a way to organize the elements.

3. Organizing the Elements
Chemists used the properties of elements to sort them into groups.

4. Mendeleev’s Periodic Table
Arranged elements in order of increasing atomic mass
The first “Periodic Table”

5. Mendeleev
He left blanks for yet undiscovered elements
But, there were problems:
Such as Co and Ni; Ar and K; Te and I

6. A better arrangement
In 1913, Henry Moseley –arranged elements according to increasing atomic number
The arrangement used today

8. The Periodic Law says:
there is a periodic repetition of their physical and chemical properties.
Horizontal rows = periods
There are 7 periods
Vertical column = group (or family)
Similar physical & chemical prop.
Identified by number(1-18)

9. H He F Al Fr 2 1 18 17 13 14 15 61 Be B Transition metals Si Ge As ScSb Te La Po At Fr Ac
Metalloids
Rare-Earth or Inner transition metals

10. Areas of the periodic table
Three classes of elements are: ) metals, 2) nonmetals, and ) metalloids
Metals: electrical conductors, have luster, ductile, malleable
Nonmetals: generally brittle and non-lustrous, poor conductors of heat and electricity

11. Metallic Character
Metals
Nonmetals
Metalloids

12. Areas of the periodic table
Notice the stair-step line?
Metalloids: border the line-2 sides
Properties are intermediate between metals and nonmetals

13. Squares in the Periodic Table
The periodic table displays the symbols and names of the elements

15. Groups of elements - family names
Group I – alkali metals
Forms a “base” (or alkali) when reacting with water
Group 2 – alkaline earth metals
Group 17 – halogens
Means “salt-forming”

16. Noble gases are the elements in Group 18
Groups
Noble gases are the elements in Group 18
they rarely take part in a reaction; very stable = don’t react

17. Group 1 are the alkali metals (but NOT H)
Group 2 are the alkaline earth metals H

18. Group 18 are the noble gases
Group 17 is called the halogens

19. H He F Al Fr 1 Alkali metals 18A Noble Gases 2 Alkaline earth metals
17 Halogens 13 14 15 61 H He Be B F
Transition metals Al Si Ge As Sc Sb Te La Po At Fr Ac
Metalloids
Rare-Earth or Inner transition metals