Periodic Table

Mendeleev• Dmitri Mendeleev (1869, Russian)– Organized elements

by increasing atomic mass.

– Elements with similar properties were grouped together.

– There were some discrepancies.

Mendeleev• Dmitri Mendeleev (1869, Russian)– Predicted properties of undiscovered

elements.

Moseley

• Henry Mosely (1913, British)

– Organized elements by increasing atomic number.

– Resolved discrepancies in Mendeleev’s arrangement.

Mendeleev’s Periodic Table

Dmitri Mendeleev

Modern Russian Table

Stowe Periodic TableStowe Periodic Table

A Spiral Periodic TableA Spiral Periodic Table

“Mayan” Periodic

Table

The Periodic Table

Period

Group or family

Period

Group or Family

• Horizontal rows are called Periods or Series There are 7 periods

6

3

4

5

1

7

2

• Vertical columns are called Groups.• Elements are placed in columns by similar

properties.• Also called families

• Main Group Elements• Transition Metals• Inner Transition

Metals

Blocks

1A

2A 3A 4A 5A 6A 7A

8A• The elements in the A groups are called the representative elements

The group B are called the transition elements

These are called the inner transition elements and they belong here

• Group 1A are the alkali metals• Group 2A are the alkaline earth metals

• Group 7A is called the Halogens• Group 8A are the noble gases

• Metals• Nonmetals• Metalloids

Metallic Character

Easily lose valence electron (Reducing agents)

React violently with water Large hydration energy React with halogens to form

salts

The Properties of a Group: Alkali Metals

Examples of Metals

Potassium, K reacts with water and must be stored in kerosene

Zinc, Zn, is more stable than potassium

Copper, Cu, is a relatively soft metal, and a very good electrical conductor.

Mercury, Hg, is the only metal that exists as a liquid at room temperature

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

Examples of Nonmetals

Sulfur, S, was once known as “brimstone”

Microspheres of phosphorus, P, a reactive nonmetal

Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

Properties of Metalloids

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

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

Periodicity Explained

• Valence = Outer shell electrons• The orbitals fill up in a regular

pattern• The outer shell electron

configuration repeats• The properties of atoms therefore

repeat when placed in order of Atomic Number

1s1

1s22s1

1s22s22p63s1

1s22s22p63s23p64s1

1s22s22p63s23p64s23d104p65s1

1s22s22p63s23p64s23d104p6 5s24d10 5p66s1

1s22s22p63s23p64s23d104p65s24d105p6 6s24f145d106p67s1

H1

Li3

Na11

K19

Rb37

Cs55

Fr87

He2

Ne10

Ar18

Kr36

Xe54

Rn86

1s22s22p63s23p64s23d104p6

1s22s22p63s23p64s23d104p65s24d105p6

1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p6

1s2

1s22s22p6

1s22s22p63s23p6

• Alkali metals all end in s1

• Alkaline earth metals all end in s2

• really have to include He but it fits better later.

• He has the properties of the noble gases.

s2s1 s- block

Transition Metals - d block

d1 d2 d3 d4 d5 d6 d7 d8 d9 d10

The p-block p1 p2 p3 p4 p5 p6

f - block

• inner transition elements

f1 f5f2 f3 f4

f6 f7 f8 f9 f10 f11 f12 f14

f13

Writing Electron configurations the easy

way

Yes there is a shorthandYes there is a shorthand

Electron Configurations repeat

• The shape of the periodic table is a representation of this repetition.

• When we get to the end of the column the outermost energy level is full.

• This is the basis for our shorthand.

The Shorthand• Write the symbol of the noble gas

before the element.• Then the rest of the electrons.• Aluminum - full configuration.

• 1s22s22p63s23p1

• Ne is 1s22s22p6

• so Al is [Ne] 3s23p1

More examples• Ge = 1s22s22p63s23p64s23d104p2

• Ge = [Ar] 4s23d104p2

• Hf = 1s22s22p63s23p64s23d104p65s2

4d105p66s24f145d2

• Hf=[Xe] 6s24f145d2

The Shorthand Again

Sn- 50 electrons

The noble gas before it is Kr

[ Kr ]

Takes care of 36

Next 5s2

5s2

Then 4d10

4d10Finally 5p2

5p2