2. The Periodic Table…an arrangement of elements according to similarities in properties.

3. Development Dimitri Mendeleev, 1834 - 1907 first periodic table
first periodic table
organized elements into columns by increasing atomic mass
left blank spaces for undiscovered elements

4. 70 elements had been discovered
mid-1800s
70 elements had been discovered

5. determined the atomic number of elements
Henry Moseley, 1913
created the modern periodic table
determined the atomic number of elements
used the atomic number instead of atomic mass to organize the periodic table 

6. Periodic Law
When the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.

7. Basic Organization Periods horizontal rows numbered 1 – 7
bottom two rows, inner transition elements

8. Groups or Families vertical columns
similar properties within each group
18 in total

9. Main Sections
Representative elements
groups 1, 2, 13 – 18

10. Transition elements
groups 3 – 12
all metals

11. Inner transition elements
bottom two rows
lanthanoid series, #57 – 71
actinoid series, #89 – 103 (all are radioactive)

12. Metals 80% of all elements
left side of periodic table (except for hydrogen)
80% of all elements
ductile (stretched into wire) AND malleable (flattened into thin sheets)
luster
all but one solid at room temperature, 20C (Hg only metal liquid at room temp.)
good conductors of heat and electricity
high densities, high boiling points and melting points

13. =
METALS

14. Nonmetals right side of periodic table
poor conductors of heat and electricity
solids and gases at room temp. (Br only liquid at room temp.)
not malleable or ductile
brittle
no luster, dull
low densities, low boiling and melting points

15. =
NONMETALS

16. Metalloids properties between those of metals and nonmetals
on stair step line EXCEPT for ALUMINUM, Al (B, Si, Ge, As, Sb, Te, Po)
properties between those of metals and nonmetals
all are solids at room temperature

17. =
METALLOIDS

18. Group Names Group 1 ALKALI Metals
most reactive group, react violently with water
1 electron in the outer shell
very soft , can be cut with a knife

19. Group 2 ALKALINE EARTH Metals 2 electrons in outer shell

20. Group HALOGENS
“salt-makers”
7 electrons in outer shell
individually poisonous, but in a compound they are harmless

21. Group NOBLE GASES
INERT gases/nonreactive (do not react) with other elements
8 electrons in their outer shell