1. PERIODIC TABLE

2. Periodic Table J.W. Döbereiner Useful
1829—TRIADS, groups of the elements
similar in chemical and physical properties
properties based on atomic mass
Useful
Triads were useful b/c they grouped elements together that had similar properties
For the first time a pattern was observed based on atomic mass

3. Periodic Table Dmitri Mendeleev Chem. Prof. In St. Petersberg, 1869
(the big dawg of the Periodic Table)
Chem. Prof. In St. Petersberg, 1869
Noticed patterns within the elements that Döbereiner described
Organized the elements further
Published the first chart in 1869
elements increased in size from top to bottom (groups)
elements that shared properties went in same rows from left to right (periods)

4. Periodic Table Dmitri Mendeleev patterns repeated each period
a second table was published later
more elements
further speculation
patterns repeated each period

5. Periodic Table

6. Periodic Table Dmitri Mendeleev patterns repeated each period
a second table was published later
more elements
further speculation
patterns repeated each period
vertical columns (groups) had similar properties

7. Periodic Table

8. Periodic Table Dmitri Mendeleev patterns repeated each period
a second table was published later
more elements
further speculation
patterns repeated each period
vertical columns (groups) had similar properties
horizontal rows (periods) had patterns of changing properties

9. Periodic Table

10. Periodic Table Dmitri Mendeleev patterns repeated each period
a second table was published later
more elements
further speculation
patterns repeated each period
vertical columns (groups) had similar properties
horizontal rows (periods) had patterns of changing properties

11. Periodic Table Dmitri Mendeleev
His table was first to show Periodicity
tendency to reoccur, i.e.—moon every month or Halley’s comet every 76 years
True Brilliance
left spaces for undiscovered elements
all based on properties
even speculated (correctly) on those properties

12. Periodic Table Modern Table Very similar to Mendleev’s
periodicity still seen
Arranged by atomic number (# of protons) rather than atomic mass
except for first period, all periods start with a metal and end with a noble gas

13. ATOM ION ISOTOPE Periodic Table Three types of elements…
Smallest unit of an element that has the same properties as the element
ION
An atom that has lost or gained one or more electrons—it is charged (+/-)
ISOTOPE
Atom with the same number of PROTONS but different number of NEUTRONS than other atoms of the same element (different atomic mass)

14. Periodic Table Ions TRANSFER of electrons
Atoms that transfer electrons become IONS
GAIN electron = NEGATIVE ion/ or anion
LOSE electron = POSITIVE ion or cation

15. Periodic Table Sodium atom 11 electrons (-) 11 protons (+) Sodium ion
Why Do Ions have a charge?
Sodium atom
11 electrons (-)
11 protons (+)
Sodium ion
10 electrons (-)
11 protons (+)
0 (+/-)
1 +

16. Periodic Table Nitrogen atom 7 electrons (-) 7 protons (+)
Why Do Ions have a charge?
Nitrogen atom
7 electrons (-)
7 protons (+)
Nitrogen ion
10 electrons (-)
7 protons (+)
0 (+/-)
3 –

17. Oxidation Number Periodic Table Nitrogen ion 10 electrons (-)
Why Do Ions have a charge?
Nitrogen ion
10 electrons (-)
7 protons (+)
Oxidation Number
3 –
IONIZATION: process of becoming an ion

18. Periodic Table
Ions
You can use the periodic table to determine the charge an ion will have
It’s all about valence electrons and the octet rule
1,2,3 valence electrons—give them away “cheaper” = +1, +2, +3
5,6,7 valence electrons—take in new e-s “cheaper” = -3,-2,-1

19. Periodic Table Ions—Bonding Capacity
Once you have determined the oxidation number you can determine how many bonds
+1, bonds once
-1, bonds once
+3, bonds 3 times
-3, bonds 3 times

20. Periodic Table There are several important trends in the PT:
Ionization Energy
Electronegativity (electron affinity)
Atomic Radius
Periodicity is the study of the trends of the periodic table.

21. Ionization Energy
Ionization energy, E1, is the energy needed to remove the most loosely held electron from a neutral gaseous atom.
As we go across the P.T., E1 increases because you have more protons (more + charges)
As we go down the P.T., E1 decreases because the e- is further away from the nucleus

22. Ionization Energy

23. Electronegativity (E- affinity)
Electronegativity is the attraction of an atom for e- in the covalent bond.
The most EN element is fluorine(F) with a value of 4.0
As we go across the P.T., EN goes up, and as we go down the P.T., EN goes down.

24. Electronegativity (E- affinity)
HYDROGEN: 2.1
OXYGEN: 3.44
Water is polar because the electrons are more attracted to the oxygen than the hydrogen

25. Atomic Radius
Atomic radius is the distance between the nucleus of an atom and its valence shell when that atom has formed a covalent bond.
Size of atomic radius determined by:
Nuclear charge (number of protons)
Shielding of outer shell electrons by inner shell electrons
Across PT, radius decreases because electrons are more strongly attracted to the nucleus and shielding remains same.

26. Atomic Radius
As we go down the P.T., atomic radius increases because there are more energy levels
As we go across the P.T., atomic radius decreases because the atoms are getting smaller (more p+, stronger attraction of electrons)

27. Summary of Trends
Ionization Energy
Atomic Radius
Electronegativity

28. The End!