1. The Periodic Table
Chemistry

2. Origin of Periodic Table
Triads - groups of 3 elements with similar properties
(Dobereiner – 1817)
Law of Octaves – properties of elements repeat every 8 elements
(Newlands – 1863)

3. Origin of Periodic Table
Dimitri Mendeleev – 1869
Properties of elements are periodic functions of their atomic masses.
Developed 8 column table
Left spaces for undiscovered elements
Columns contained elements with similar properties
Problems with Ni, I, K (Why?)

4. Origin of Periodic Table
X-ray experiments by Mosley (1913) led to discovery of atomic numbers.
Modern Periodic Law – properties of elements are periodic functions of their atomic numbers.

5. Organization of Periodic Table
Rows are called periods.
Columns are called families or groups.
All elements in a family have similar properties.
Octet Rule – elements with 8 valence electrons are unreactive

6. Periodic Table
Rows = Periods
Columns = Families or Groups

7. Chemistry Chapter 5
The Periodic Law

8. Mendeleev’s Periodic Table
Dmitri Mendeleev

9. Periodic Table with Group Names

10. Alkali Metals
1st column in blue

11. The Properties of a Group: the Alkali Metals
Easily lose valence electron
(Reducing agents)
React violently with water
Large hydration energy
React with halogens to form salts
H- Hydrogen Rb- Rubidium
Li-Lithium Cs- Cesium
Na-Sodium Fr-Francium
K-Potassium

12. Properties of Metals
Metals are good conductors of heat and electricity
Metals are malleable
Metals are ductile
Metals have high tensile strength
Metals have luster

13. Examples of Metals
Potassium, K reacts with water and must be stored in kerosene
Copper, Cu, is a relatively soft metal, and a very good electrical conductor.
Zinc, Zn, is more stable than potassium
Mercury, Hg, is the only metal that exists as a liquid at room temperature

14. Alkaline Earth Metals
2nd column - green

15. Properties of alkaline metals
Be, Mg, Ca, Sr, Ba, Ra
The alkaline earth metals, or alkaline earths, are beryllium, magnesium, calcium, strontium, barium, and radium.
Possess many properties of metals
Low electro negativities
Low electron affinities
They have smaller atomic radii than the alkali metals

16. Transition Metals all have similar properties
Middle – purple and can give up different amounts of electrons at different times

17. Properties of Metalloids
B- Boron As- Arsenic At- Astatine
Ge- Germanium Te-Tellurium
Sb- Antimony Si- Silicon
Al-Aluminum Po- Polonium
Metalloids straddle the border between metals and nonmetals on the periodic table.
They have properties of both metals and nonmetals.
Metalloids are more brittle than metals, less brittle than most nonmetallic solids
Metalloids are semiconductors of electricity
Some metalloids possess metallic luster

18. Silicon, Si – A Metalloid
Silicon has metallic luster
Silicon is brittle like a nonmetal
Silicon is a semiconductor of electricity
Other metalloids include:
Boron, B
Germanium, Ge
Arsenic, As
Antimony, Sb
Tellurium, Te

19. Properties of Nonmetals
Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
Nonmetals are poor conductors of heat and
electricity
Nonmetals tend to be brittle
Many nonmetals are gases at room temperature

20. Examples of Nonmetals
Microspheres of phosphorus, P, a reactive nonmetal
Sulfur, S, was once known as “brimstone”
Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

21. Right of the stair-step line
Non-Metals
Right of the stair-step line
C-Carbon, N- Nitrogen, O-Oxygen, P-Phosphorus, Cl-Chlorine, Se-Selenium

22. 7th tall column (light orange)
Halogens
7th tall column (light orange)
F-fluorine Cl-Chlorine Br-Bromine
I- Iodine

23. Properties of Halogens
a particular class of nonmetals.
Very high electronegativities
Seven valence electrons (one short of a stable octet)
Highly reactive, especially with alkali metals and alkaline earths
Halogens range from solid (I2) to liquid (Br2) to gaseous (F2 and Cl2) at room temperature.

24. last tall column (yellow)
Noble Gases
last tall column (yellow)
He-Helium Ne-Neon Ar-Argon
Kr-Krypton Xe-Xenon

25. Properties of Noble gases
Unreactive gases
Odorless
Colorless
All produce light when an electric current is applied

26. Lanthanides – Ce row
Actinides – Th row

27. Determination of Atomic Radius:
Half of the distance between nucli 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

28. Table of Atomic Radii

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

31. Table of Electron Affinities

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

33. Summation of Periodic Trends

34. Table of Ion Sizes

35. 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

36. Periodic Table of Electronegativities