Feb 20, 2011

Periodic table of elements

In the modern periodic table, the elements are arranged accordingly with the increasing no. of atomic number (no. of protons) from first hydrogen to the 118th element.This periodic table reveals many properties of elements periodically.The basic periodical properties, that we can gain from this table are as follows.
1) Size of the atom.
2) Atomic radii
3) Ionization potential
                                                                             4) Electro negativity and
    Download periodic table software.                          5) Electron affinity
Size of the atom:
In the periodic table the size of the atom decreaes from left to right, and increases from top to bottom.It is a periodical one and there may be some breakage.
The size of an atom is inversely proportional to the effective nuclear charge.
Why it is?
The effective nuclear charge represents the electrostatic force of attraction between the protons and electrons.If the force between them is higher, i.e. effective nuclear charge is higher then they become more compact leading to decrease in size.
Ok.. then from top to bottom, why it increses?
You can see in the table that from left to right the principal quantum no. of the atom is same.For instance Li lithium has the value 1,2 and the same Ne neon has.But in case of moving from top to bottom the principal quantum no. increases constantly by one.This is the answer for the above question.
Atomic radii:
The atomic radii is directly proportional to size of the atom.
The radius of larger circle will be greater than the smaller one.Similarly the radius of large sized atom will greater than the smaller.
Ionization potential:
Ionization potential is defined as the amount of energy requires to remove an most loosely bound electron from the valence or outer shell of an atom to become cation or positive ion.  It is also known as electron gain enthalpy.
The Ionization potential usually increses from left to right and decreaes from top to bottom in the periodic table.
Ionization potential is directly proportional to effective nuclear charge.
Electro negativity:
Electro negativity is defined as the relative tendency of an atom to attract electrons towards itself to become stable.Usually electronegativity increses from left to right and decreses from top to bottom.
The halogens (7th column) has the highest electro negativity value.Among them Fluorine F, has higher value.
Electron affinity:
It is defined as the energy released, when an extra electron enters the valence shell of isolated neutral atom to form negative ion or anion.
Electron affinity is directky proportional to electronegativity.


  1. just wanted to let you know that the mw of K is 39.10, not 30.10

  2. "kwalts" is correct. The number under "K" should be 39.10, not 30.10

  3. I believe there are more than just five metalloids, what about Boron?