1. Chapter 5
The Periodic Law

2. Modern Russian Table

3. Chinese Periodic Table

4. Orbital Filling Table

5. Periodic Table with Group Names

6. Chapter 5
The Periodic Law
5.1 History of the Periodic Table

7. Predecessors to the Modern Periodic Table
Dobereiner’s Triads
J.W. Dobereiner classified some elements into groups of three, which he called triads.
similar chemical properties
physical properties varied in an orderly way according to their atomic masses.

8. Mendeleev’s Periodic Table
Dmitri Mendeleev

9. Predecessors to the Modern Periodic Table
Mendeleev’s Periodic Table
Dmitri Mendeleev realized that the chemical and physical properties of the elements repeated in an orderly way when he organized the elements according to increasing atomic mass.
In 1869, Mendeleev published a table of the elements organized by increasing atomic mass.
Mendeleev was a Russian scientist and is often referred to as the “Father” of the Periodic Table.
Periodicity is the tendency to recur at regular intervals.

10. Mendeleev’s Table "The chemical properties of the elements are a periodic function of their atomic weights"

11. Mendeleev's Periodic Table
Vertical columns in atomic weight order
Horizontal rows have similar chemical properties
Mendeleev made some exceptions to
place elements in rows with similar
properties (tellurium & iodine's places were switched)
Missing Elements: gaps existed in Mendeleev’s table
Mendeleev predicted the properties of the “yet to be discovered” elements
(scandium, germanium and gallium)

12. Problems with Mendeleev’s Table
Why didn't some elements fit in order of increasing atomic mass?
Moseley helped to clarify some of the problems…
Why did elements exhibit periodic behavior?

13. Henry Moseley
English physicist who determined the number of positive charges in the nucleus (protons) by measuring the wavelength of the x-rays given off by certain metals in 1913.
He was killed by a sniper in Turkey in August 1915 during WWI. Many people think that Britain lost a future Nobel Prize winner. This is because Nobel Prizes, the most prestigious awards for scientific achievement are awarded only to living people.

14. Moseley and the Periodic Table
Protons and Atomic Number:
X-ray experiments revealed a way to determine the number of protons in the nucleus of an atom
The periodic table was found to be in atomic number order, not atomic mass order!!!
This explained tellurium-iodine anomaly
***Moseley was killed in battle in 1915, during WWI. He was 28 years old
The Periodic Law
The physical and chemical properties of the elements are periodic functions of their atomic numbers

15. Discovery of the Noble Gases
William Ramsay discovers argon
Ramsay discovers krypton and xenon
Helium discovered as a component of the sun, based on the emission spectrum of sunlight
Ramsay finds helium on Earth
Freidrich Dorn discovers radon
1868
1894
1895
1898
1900
Sir William Ramsay

16. The Lanthanides
Early 1900's the elements from cerium (#58) to lutetium (#71) are separated and identified. Also known as the rare earth elements, less than 0.01% naturally occurring.
The Actinides
Discovery (or synthesis) of thorium, # 90 to lawrencium #103
Both groups pulled out of the table for space reasons.
Periodicity:
Elements with similar properties are found at regular intervals within the "periodic" table

18. 5.2 Electron Configuration & The Periodic Table
Chapter 5
The Periodic Law
5.2 Electron Configuration & The Periodic Table

19. Sublevel Blocks on the Periodic Table1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Sublevel Blocks on the Periodic Table

20. The Properties of a Group: the Alkali Metals
Easily lose 1 valence electron
(Reducing agents)
React violently with water
React with halogens to form salts

21. The Properties of a Group: the Alkali Earth Metals
Easily loses 2 valence electron
(Reducing agents)
Harder, denser, stronger than Group 1 metals
Higher melting points
Less reactive than Group 1, but too reactive to be found free in nature

22. 5.3 Electron Configuration & Periodic Properties
Chapter 5
The Periodic Law
5.3 Electron Configuration & Periodic Properties

23. Determination of Atomic Radius:
Half of the distance between nuclei in
covalently bonded diatomic molecule
"covalent atomic radii"
Periodic Trends in Atomic Radius:
Radius decreases across a period
Increased effective nuclear charge due
to decreased shielding
Radius increases down a group
Addition of principal quantum levels

24. Table of Atomic Radii

25. How to Achieve an Octet…
Atoms can form ions by gaining or losing electrons to obtain a stable outer configuration
Cation- Positive ion (+) ion
Anion- Negative ion (-) ion
Ions attract (opposites attract)

26. Predicting Ionization
Metals tend to lose electrons
They form cations.
Ex: Na, 1s22s22p63s1 becomes Na+1,1s22s22p6
Nonmetals tend to gain electrons.
They form anions.
Ex: O, 1s22s22p4 becomes O-2, 1s22s22p6

27. Electron Transfer: Anions
When an atom gains electrons it increases its negative charge so it becomes negatively charged. There are now more electrons than protons.
X + e- = X –
Ex: Nitrogen Atom + 7 protons
- 7 electrons
Nitrogen Ion +7 protons
- 10 electrons
Neutral
-3 charge

28. Electron Transfer: Cations
When an atom loses electrons, it loses negative charges so it becomes more positively charged. There are now more protons than electrons.
X - (e-) = X +
Ex: Potassium Atom protons
- 19 electrons
Potassium Ion +19 protons
-18 electrons
Neutral
+1 charge

29. Ionization Energy - the energy required to remove an electron from an atom
Increases for successive electrons taken from
the same atom
Tends to increase across a period
Electrons in the same quantum level do not shield as effectively as electrons in inner levels
Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove
Tends to decrease down a group
Outer electrons are farther from the nucleus

30. Ionization of Magnesium
Mg kJ  Mg+ + e-
Mg kJ  Mg e-
Mg kJ  Mg e-

31. Table of 1st Ionization Energies

32. Another Way to Look at Ionization Energy

33. Electron Affinity - the energy change associated with the addition of an electron
Affinity tends to increase across a period
Affinity tends to decrease down a group
Electrons farther from the nucleus
experience less nuclear attraction
Some irregularities due to repulsive
forces in the relatively small p orbitals

34. Table of Electron Affinities

35. Ionic Radii Cations Anions Positively charged ions
Smaller than the corresponding
atom
Anions
Negatively charged ions
Larger than the corresponding
atom

36. Summation of Periodic Trends

37. Table of Ion Sizes

39. Electronegativity A measure of the ability of an atom in a chemical
compound to attract electrons
Electronegativities tend to increase across
a period
Electronegativities tend to decrease down a
group or remain the same

40. Periodic Table of Electronegativities