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Trends in the Periodic Chart …position electrons physical and chemical properties…

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Presentation on theme: "Trends in the Periodic Chart …position electrons physical and chemical properties…"— Presentation transcript:

1 Trends in the Periodic Chart …position electrons physical and chemical properties…

2 …the position indicates physical and chemical properties of elements!

3 There are two effects: Attraction Shielding

4 There are two effects: Attraction as Z increases, attraction increases BUT Shielding as Z increases, shielding increases: --a little bit with each electron in the same period --in a great jump as you start the next period

5 Shielding Shielding is the weakening of attraction due to electrons interfering with the attraction of the nucleus Shielding increases a little as you go across a period (not as much as attraction) Shielding jumps tremendously as you start a new energy level

6 Periodic trends

7 Simple Valence electrons –The representative (tall) columns represent the number of valence electrons –Transition elements have only two valence electrons, but have a part-filled d sublevel

8 How many valence electrons?

9 Simple Electron configurations

10 EC ends in…

11 ns 1 ns 2 * **

12 EC ends in… ns 2 (n-2)f 14 (n-1)d ? * ns 2 (n-1)d ? * ns 2 (n-2)f ? *

13 EC ends in… * ns 2 np ? * * ns 2 (n-1)d 10 np ? ns 2 (n-2)f 14 (n-1)d 10 np ?

14 Simple Ionization pattern Metals have -only a few valence electrons -lose these electrons to empty their valence level -form positive ions

15 Simple Ionization pattern Non-metals have -more valence electrons -gain electrons to fill valence level -form negative ions

16 What is the charge on the ion?

17 Medium Atomic size In a column, a lower row indicates an extra energy level Outer energy levels are larger (due to shielding) The largest atom in a column is the bottom element

18 Medium Ionization energy

19 Medium Ionization energy the energy required to remove an electron X + IE X + + e - Outer energy levels are farther from the nucleus It is easier to remove an electron from a larger energy level The lowest ionization energy is at the bottom of the column

20 Medium Electronegativity the attraction an atom has for a shared pair of electrons See previousthe highest electronegativity is at the top

21 Medium Electron affinity the attraction an atom has for an electron from outside X + e - X - + EA See previousthe highest electron affinity is at the top

22 One moment… As you go across a row, you get more protons in the nucleus They attract the electrons better Each energy level gets smaller

23 Hard Atoms get smaller as you go across a row Ionization energy gets larger Electronegativity gets larger Electron affinity gets larger --All because there are more protons Z increases faster than shielding in a period

24 Recap Atomic size INCREASES as you go down and left

25 Recap Electronegativity, ionization energy, and electron affinity INCREASE as you go up and right

26 Pop Quiz Which element on the entire periodic chart is the largest? Smallest? Which element on the entire periodic chart has the largest IE? Smallest?

27 Pop Quiz Which element on the entire periodic chart has the largest e-negativity? Smallest? Which element on the entire periodic chart has the largest EA? Smallest?

28 Pop Quiz Whos your favorite pop star?

29 Which has the greatest / least: Size, IE, EA, e-neg? C Sn I F

30 The diagonal effect Of the previous four elements, the ones in the same row and column are easy, right? What can you say about carbon and iodine? Try this– they might be just about the same!

31 The metal/nonmetal line Diagonal effect! (probably electron affinity)

32 Hard (contd) Ionic radius Negative ions are (way) larger than their atom Positive ions are (way) smaller than their atom

33 Which has the largest / smallest ion? Li K Ca Be

34 Which has the smallest / largest ion? Mg Sr Te S

35 Which has the smallest / largest ion? +2-2 Mg Sr Te S

36 Hard (contd) Second and third ionizations If you ionize an atom, you make a (+) ion Its harder to ionize it again It gets way harder after you empty the valence level

37 Hard (contd) Second and third ionizations If you ionize an atom, you make a (+) ion Its harder to ionize it again It gets way harder after you empty the valence level Why?

38 Hard (contd) First, second, and third ionization energies X + IE X +1 + e - X +1 + IE 2 X +2 + e - X +2 + IE 3 X +3 + e -

39 Disclaimers Noble gasses have no electronegativity they dont share electrons Noble gasses have no electron affinity they dont gain electrons Most metals have no electron affinity they dont gain electrons

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43 Ionization Energies in kJ/mol H 1312 He Li Be B C N O F Ne Na Mg

44 Ionization Energies in kJ/mol H 1312 He Li Be B C N O F Ne Na Mg

45 Electron Affinity*, Electronegativity*, Ionization energy

46 Size

47 Atomic number, shielding, diagonal effect

48 Reactivity

49 Melting point?

50 State!

51 Know these oxides

52 Acidic BasicAmphoteric


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