Understanding the Periodic Table and Element Groupings

1. The Periodic Table

2. History • Dobereiner • Created a table of triads (Groups of three elements)

4. Newlands • Designed a table called “Law of Octaves” (Groups of 8 elements)

6. Mendeleev • Considered the “Father of our Modern Table” • Arranged the elements according to increasing atomic mass • Left blank spaces for elements not yet discovered.

7. Problems with Mendeleev’s chart • Some elements did not fall into a group with other elements like it

9. Moseley • Fixed problems in Mendeleev’s Table • Arranged the elements by increasing atomic number

12. Chinese Periodic Table

13. Arrangement of the table

14. Each element in a box Element Name Number of Atomic Number electrons in each shell Element Symbol Average atomic Mass 2 8 18 2

15. Horizontal Rows • Called Periods or Series • Indicate: • outermost energy levels being filled

16. Vertical Columns • Called families or groups • Indicate: • Chemical Properties • Same number of electrons in outer shell (valence electrons) • Number at the top of each column indicates the number of electrons in the outer shell

17. Group Names

18. Group 1 – Alkali Metals • Have 1 electron in outer shell (valence electron) • Fills “s” orbital with one electron • Most reactive metals

19. Group 2 – Alkaline Earth Metals • Has 2 electrons in the outer shell (valence electrons) • Fills s orbital with 2 electrons

20. Group 3 – Boron Family • Has 3 electrons in the outer shell • Fills p orbital with 1 electron • Contains both metals and metalloids

21. Group 4 – Carbon Family • Has 4 electrons in outer shell • Fills p orbital with 2 electrons • Contains metals, metalloids, and nonmetals

22. Group 5 – Nitrogen Family • Has 5 electrons in outer shell • Fills p orbital with 3 electrons • Contains metals, metalloids, and nonmetals

23. Group 6 – Chalcogen (oxygen) Family • Has 6 electrons in outer shell • Fills p orbital with 4 electrons • Contains metals, metalloids, and nonmetals

24. Group 7 – Halogen Family • “Salt Producers” • Has 7 electrons in outer shell • Fills p orbital with 5 electrons • Contains all nonmetals

25. Group 8 – Noble Gases • Has an octet in outer shell • Except helium – has only 2 electrons (s orbital full) • Fills p orbitals with 6 electrons • Inert gases (not reactive) • Contains all nonmetals

26. Transition Metals

27. Transition Elements • All metals • Fill the d orbitals • Members of importance • W, Fe, Co, Pt, Cu, Ag, Au, Zn, Hg • Hg – is the only liquid at room temperature

28. Nonmetals (20%) • All on the right side of the table

29. Noble Gases (5%) All elements are trying to be like the noble gases. Lewis Dot for Noble Gas .. : x : ..

30. Oxidation Numbers • Number of electrons lost, gained, or shared to form bonds All atoms trying to get 8 electrons

31. If atoms lose electrons, they go down to a lower energy level that is filled • The atom will take on a positive charge • A positively charged atom = cation

32. If atom gains electrons, they fill up the outer shell • The atom takes on a negative charge • Negatively charged atom = anion

33. Oxidation Numbers for the families • Group 1 • +1 (lose 1 electron rather than gaining 7) • Group 2 • +2 (lose 2 electron rather than gaining 6) • Group 3 • +3 (lose 3 electron rather than gaining 5)

34. Oxidation Numbers for the families • Group 4 • +4 or -4 (can gain or lose 4. It is halfway to 8; tends to share)

35. Oxidation Numbers for the families • Group 5 • -3 (gains 3 electron rather than losing 5) • Group 6 • -2 (gains 2 electron rather than losing 6) • Group 7 • -1 (gains 1 electron rather than losing 7) • Group 8 • 0 (has an octet)

36. Transition Metals • Have more than 1 oxidation number • Cu • + 1 or +2 • Fe • +2 or +3

37. Trends on the Periodic Table

38. Atomic Size • Down a family: size increases • More shells are being added • Across a period: size decreases • Nuclear charge pulls electrons in slightly

41. Activity • Down the family • On the right side of the table • Activity decreases • Down the family • On the left side of the table • Activity increases

42. Activity • Across the period • On the top of the table, the activity increases • Across the period • On the bottom of the table, the activity decreases

44. Chemical Activity • Key elements • Francium: most active metal • Fluorine: most active nonmetal

45. Bonding • 2 types • Covalent: sharing electrons • Ionic: Transfer of electrons • Forming ions (cations and anions)

46. Electronegativity • The tendency of an atom to attract electrons when bonding • Metals of low electronegativity form cations • Metals of high electronegativity form anions

48. Ionization Energy (IE) • Energy required to remove an electron • Metals: low IE (e- easily removed) • Nonmetals: high IE (e- hard to remove)

49. Across periods: • IE increases • Down a group: • IE decreases

50. 4 factors affecting IE • Nuclear charge: The greater the nuclear charge, the greater the IE • Shielding Effect: The greater the number of inner electrons, the less the IE