1. Periodic Table 4 th Lykeion of Corfu Class A

2. Dobereiner 1829 3-ades of elements with similar properties Cl, Br,I Ca,Sr,Ba etc.

3. Newlands 1863 Rule of “Octaves” 7 Li 9 Be 10 B 12 C 14 N 16 O 19 F 20 Ne 23 Na 24 Mg 27 Al 28 Si 31 P 32 S 35 Cl 36 Ar 39 K 40 Ca …… 1 5 2 34 67 8

4. Newlands

6. If all the elements be arranged in order of their atomic weights a periodic repetition of properties is obtained." - Mendeleyev Dmitri Mendeleev Lothar Meyer 1869

7. Known elements when the Mendeleev’s table established 127 Ι 129 Te ? ?

8. 1874 -1885 Discovery of Gallium (Ga), Germanium (Ge) και Scandium (Sc) Their properties were almost expectable !

9. Henry Moseley 1913 The elements may be arranged in order of their Atomic Numbers and not to their Atomic weights “ There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.” 7 Li 9 Be 10 B 12 C 14 N 16 O 19 F 20 Ne 3 Li 4 Be 5B5B 6C6C 7N7N 8O8O 9F9F 10 Ne

10. O 16 8 Mass Number Atomic Number

11. ΙΑΙΑ ΙΙ Α ΙΙΙ Α ΙVΑΙVΑ VΑVΑ VI Α VII Α VIII Α ΙΙΙ B ΙVBΙVB VBVB VI B VII B VIII B ΙBΙB ΙΙ B 1st 2nd 3rd 4th 5th 6th 7th Contemporary P.T.

12. Groups : The VERTICAL columns Elements within a group have similar properties

13. Group Ι Α ( 1 st ) or ALKALI METALS 3 Li K2 L1 11 Na K2 L8 M1 19 K K2 L8 M8 N1 37 Rb K2 L8 M18 N8 O1 55 Cs K2 L8 M18 N18 O8 P1 87 Fr K2 L8 M18 N32 O18 P8 Q1

14. Group ΙI Α ( 2nd ) or ALKALINE EARTH METALS 4 Be K2 L2 12 Mg K2 L8 M2 20 Ca K2 L8 M8 N2 38 Sr K2 L8 M18 N8 O2 56 Ba K2 L8 M18 N18 O8 P2 87 Ra K2 L8 M18 N32 O18 P8 Q2

15. Group VΙIΑ ( 17th ) or HALOGENS 9 F K2 L7 17 Cl K2 L8 M7 35 Br K2 L8 M18 N7 53 I K2 L8 M18 N18 O7 85 At K2 L8 M18 N32 O18 P7

16. Group VIΙIΑ or (O) or 18th NOBLE GASES 10 Ne K2 L8 18 Ar K2 L8 M8 36 Kr K2 L8 M18 N8 54 Xe K2 L8 M18 N18 O8 86 Rn K2 L8 M18 N32 O18 P8 2 He K2

17. Transition Metals 21 Sc K2 L8 M9 N2 22 Ti K2 L8 M10 N2 …. 39 Y K2 L8 M18 N9 O2 40 Zr K2 L8 M18 N10 O2 ….

18. Rare Earths ( Lanthanides & Actinides )

19. The horizontal rows of the periodic table are called PERIODS. 37 Rb K2 L8 M18 N8 O1 38 Sr K2 L8 M18 N8 O2 39 Y K2 L8 M18 N9 O2 ………………

20. Periodic Table Alkali Metals Alkaline Earth Metals Transition MetalsHalogensNoble Gases Lanthanides & Actinides Main Groups

21. PeriodElementsAtomic Number (Z) Fromto 1 st 2 2 nd 8 3 rd 8 4 th 18 5 th 18 6 th 32 7 th …. 12 310 1118 1936 37 54 55 86 87