2. Introduction
Now a days scientist had found 116 elements which
have their own symbol and 92 elements are natural
and 24 elements are artificial. About 150 years ago
scientist were trying to group elements together but
they failed. In 1869 one scientist name Mendeleyev
had found a best method to group those elements base
on their atomic number and known as “Periodic Table”.
3. Periodic Table
Periodic table is a tabular display of the chemical
elements, organized on the basis of their atomic
numbers, electron configurations, and recurring
chemical properties. In 1860 more than 100 European
scientist met for the first time to decide how to group
how to organise the elements including Alexander
Chancourtois, Dmitri Mendeleyev, Henry Moseley,
Johann Dobereiner, John Newlands and Lothan Meyer.
4. Sir William Crooks atomic model
Dmitri Medeleyev
John D. Clarck
Different designs prepared for
the periodic table
5.
6. Grouping Elements
Periodic table are divided into 18 groups and 7
periods. Energy level of elements increase from top to
bottom of the periodic table and atomic number of the
elements increase from left to right, top to bottom of
the periodic table. Many elements in the periodic table
are metals. Other are non metal and metalloid.
Metalloid is an element with properties intermediate
between those of a metal and non metal. For example:
silicon, boron and germonium.
7. Group
A group is a vertical column in the periodic table.
Elements which is in same group have similar
characteristic. They also have same number of
electron. From top to bottom in a group, the atomic
radii of the elements increase.
8. Period
A period is a horizontal row in the periodic table.
There are 7 periods in periodic table. Elements in the
same period show trends in atomic radius, ionization
energy, electron affinity, and electronegativity. Moving
left to right across a period, atomic radius usually
decreases.
10. Metal
70 % of the elements in periodic table are metal. They
occupy the left-hand side of the periodic table.
Characteristic of metal:
• They are shiny
• They conduct electricity and heat well
• They are found as solid at room temperature
• They lose electrons easily
• They can hammered into shape
• They can be pulled into the shape of wires
• They don’t form compounds with each other.
11. Non metal
Characteristic of non metal:
• Rarely have metallic luster (shine)
• Generally gases at room temperature
• Neither malleable nor ductile
• Brittle and dull
• Poor conductors of heat and electricity
• Usually exist as molecules in their elemental form
• Combine with other nonmetals to form covalent
• Generally form negative ions, e.g. Cl-, SO4
2-, and N3-
• High electronegativity
• High ionization energy
• Small atom size
• Gain electrons to complete their octet
• Low boiling and heating points
• Mostly in liquid or gas form
