Chapter 4 – The Periodic Table

• Developed by Mendeleev

• His work led to the Periodic Law which states that chemical and physical properties of the elements are periodic functions of their atomic number

General Analysis of the Periodic Table

• Each row is called a period• Elements are arranged in order of increasing Z

(atomic number)• Each column is called a group or family• Plays a significant part in predicting properties of

elements• There are 18 columns • The MAIN GROUPS are the first two groups and

groups 13 to 18

• The periodic table is arranged by electron structure (according to valence electrons) since they determine chemical properties

Periods

• Not much significance but some characteristics to note:

• In general,the number of the period is the same number of the energy level where the valence e- are foundExample: oxygen

• Found in the 2nd period so its valence e- are located in the 2nd energy level

Short Periods

• Periods 1, 2, and 3

• Period 1 elements hold only a maximum of 2e-

• Periods 2 and 3 elements hold a maximum of 8 e-’s

Fourth and fifth periods

• Are long periods as they contain 18 elements

• Contain elements with electrons in the d-orbital

• The elements in the d-block are called transition metals

• They form positive ions which have incomplete d-orbitals

Sixth & Seventh Periods

• 6th period contains 32 elements• 7th period contains space for 32 elements-but only

23 are known• A section has been “removed” and placed on the

bottom• The top period is called the “lanthanides” – all

contain e-’s in the 4f-orbital• The bottom period is called the “actinides” and all

elements contain e-’s in the 5f orbital

Other features on the Periodic Table

A) Metals• Make up the largest

portion• have luster, ductile

and malleable• conduct electricity• High melting and

boiling points

B) non-metals• Non-conductors of

electricity• Low boiling point• Can be solid, liquid or

gas• Non-lustrous

c) Metalloids• Semi-conductors• Have properties of

both a metal and non-metal