Question

can some one explain me what is this spdf sub shell all about?

Answer 1

it's for ur electron connfiguration. http://www.teachersdomain.org/assets/wgbh/phy03/phy03_doc_qmechatom/phy03_doc_qmechatom.pdf

Answer 2

First understand that atoms have a heavy (relatively speaking) nucleus (composed of protons and neutrons) surrounded by an electron cloud.
Originally the very small subatomic objects were thought to be like little hard spheres. Based upon observations of planets orbiting the sun, the electrons were said to be in orbit around the nucleus. This is where the term "atomic orbital" came from.
But electrons are not little hard balls. They do not orbit the nucleus but exist as clouds which surround the nucleus. These clouds can contain different amounts of energy depending upon their location and shape.
The s p d f g business comes out of quantum mechanic mathematics, based upon equations first studied by man called Schrödinger. In order to solve the equations, the electrons could only contain certain set amounts of energy. These energy levels became associated with a set of numbers. These numbers can only be whole numbers (or very simple fractions like 1/2).
The most important number (in terms of the energy of the electron) is called the Principal Quantum Number. It is associated with the Shell that contains the electron. Shells are also called Levels and sometimes Orbits. The higher the Shell number, the more distance (space) is between the electron and the nucleus.
The Second number has many names, most of which are confusing. This number divides the Shells into Subshells (also called Sublevels or Orbitals). These have different shapes. When this number is 0 (zero) the shape looks like a sphere (from the outside of the atom). This is the s subshell or orbital.
As the number increases, additional shapes are "seen." Second number = 1 gives p subshells, Second number = 2 gives d subshells, etc.
The mathematics behind the shapes defined by the quantum numbers is very difficult (to the point that many chemists do not fully understand exactly what all this means).
If you follow the graphics of the sites below, you should get a good idea of the shapes defined by this Second quantum number, even if you cannot follow the math.