1. by SeLly in Sept 2008, PTK 1 Indicator Explaining the tendency of an element to stable Writing the arrangement of valence electron of noble gas (duplet and octet) and the valence of electron of non noble gas

2. by SeLly in Sept 2008, PTK 2 Among of the all elements in this nature, only group VIIIA (noble gas) elements representing the most stable elements (difficult to form compound). Therefore, the noble gas elements generally stay in the form of free atoms (monoatomic gases) The stability of the noble gas elements caused by the noble gases atoms have the unique electron configuration

3. by SeLly in Sept 2008, PTK 3 He = 2 The electron configuration of noble gas elements Ne = 2 8 Ar = 2 8 8 Kr = 2 8 18 8 Xe = 2 8 18 18 8 Rn = 2 8 18 32 18 8

4. by SeLly in Sept 2008, PTK 4 Generally, the electron configuration of noble gas elements have 8 valence electrons (octet configuration), except helium element having 2 valence electrons (duplet configuration) Cause of that, the noble gas elements difficult to react and represent the most stable elements among other elements

5. by SeLly in Sept 2008, PTK 5 The elements that don’t have a noble gas configuration, tend to attain such a configuration through a certain chemical reaction. Stable molecules are form when the atoms combine so as to have 8 electrons in outer shells (form octet configuration) Lewis-Kossel’s octet principle So, every element have tendency to reach the stability by form a bond with another element

6. by SeLly in Sept 2008, PTK 6 Writing method of valence electron configuration of the bonded atoms using a sign Lewis Symbol Lewis symbol made by writing down symbol of the atom and encircle by dots or lines or crosses or stars expressing the number of valence electron of the atom.

7. by SeLly in Sept 2008, PTK 7 Group IA H Group IIA Mg Group IIIA Al Group IVA C Group VA N Group VIA O Group VIIA F Group VIIIA Ne

8. by SeLly in Sept 2008, PTK 8 Now, you can try to draw the Lewis symbol of : 3 Li 2 Be 5B5B 14 Si 15 P 16 S 35 Br 18 Ar

9. 9 The electron configuration of atom with tendency to release the electron The elements which have a little of valence electron, such as group IA (except H atom), IIA and IIIA have tendency follow the octet principle That elements release the valence electron to form positive ion Electropositive element The charge values according to valence electron of atoms Atoms which have tendency to release the electrons that have a little relative of ionization energy The metal elements

10. by SeLly in Sept 2008, PTK 10 Forming the positive ions of some elements AtomElectron configuration of atom The number of releasing electron Ionic form Electron configuration of ion (Octet configuration) According to the noble gas 11 Na 2 8 11 Na + 2 8 10 Ne 19 K 2 8 8 11 K+K+ 2 8 8 18 Ar 12 Mg 2 8 22 Mg 2+ 2 8 10 Ne 20 Ca 2 8 8 22 Ca 2+ 2 8 8 18 Ar 13 Al 2 8 33 Al 3+ 2 8 10 Ne

11. by SeLly in Sept 2008, PTK 11 The electron configuration of atom with tendency to accept the electron The elements which have many valence electron such as group IVA, VA, VIA and VIIA have tendency follow the octet principle That elements accept the electron to form negative ion Electronegative elements The charge value is the number of electron that was accepted The elements that have tendency to accept the electron have many relative of electron affinity or electro negativity Non metals elements

12. by SeLly in Sept 2008, PTK 12 Forming the negative ions of some elements Atom Electron configuration of atom The number of electron accept Ionic form Electron configuration of ion (octet configuration According to the noble gas 9F9F 2 77F-F- 2 8 10 Ne 17 Cl 2 8 77Cl - 2 8 8 18 Ar 8O8O 2 66O 2- 2 8 10 Ne 16 S 2 8 66S 2- 2 8 8 18 Ar 7N7N 2 55N 3- 2 8 10 Ne 15 P 2 8 55P 3- 2 8 8 18 Ar

13. by SeLly in Sept 2008, PTK 13 Kind of chemical bonding 1. Ionic bonding 2. Covalent bonding 3. Coordinate covalent bonding Metallic bonding