Question

describe the structure of an atom?

Answer 1

For basic understanding: http://en.wikipedia.org/wiki/Atom
Some insight (history is always a key part of science!): http://craigjm.tripod.com/physics.html
For deeper understanding of the atom, study 3.091. ;)

Answer 2

atom basically consist of three particles electron,proton and neutron.Proton and neutron resides inside the nucleus,while electron revolve around them in the fixed orbits,which is well defined acc. to the energy.atom as a whole is electrically neutral,because it contains electron and proton in equal nos..electron contain -ve charge,proton contains +ve charge and neutron has no charge.