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chemistry test sheet in 2001 contain 15 number of problem, that are, electron configuration, equilibrium of reaction, acid and base, the atom hydrogen and specifies characteristics, mol, hydroxides acid and isomer

here we post a litle tutorial about atom configuration, hope this help you much

The electron configuration of an atom is a form of notation which shows how the electrons are distributed among the various atomic orbital and energy levels.  The format consists of a series of numbers, letters and superscripts as shown below:

1s²

• The large number “1″ refers to the principle quantum number “n” which stands for the energy level.  It tells us that the electrons of helium occupy the first energy level of the atom.
• The letter “s” stands for the angular momentum quantum number “l”.  It tells us that the two electrons of the helium electron occupy an “s” or spherical orbital.
• The exponent “2″ refers to the total number of electrons in that orbital or sub-shell.  In this case, we know that there are two electrons in the spherical orbital at the first energy level.