electron configuration is a description
of where the electrons are around the
nucleus of an atom why is it so
important because the electron
configuration of the outer shell of an
atom that is where the electrons that
are farthest from the nucleus are
located determines many properties of
the atom for example both sodium and
potassium explode when they enter in
contact with water calcium however does
not this happens because the electron
configuration of the outer shell is the
same for sodium and potassium but it is
different for calcium to make things
easier the electrons in the outer shell
are called valence electrons the
electrons closer to the nucleus are
called core electrons valence electrons
are responsible for the different
behavior of atoms for the formation of
different ions and for chemical bonds
the question is how do we determine how
many valence electrons does an atom have
to answer this question we need to
understand where all the electrons of an
atom are we know that electrons exist in
orbitals that surround the nucleus
electrons that occupy different orbitals
will have a different distance from the
nucleus and a different energy the
further they are from the nucleus the
higher the energy there is an easy way
to visualize the orbitals around an atom
in this diagram each group of circles
represents a shell for simplicity the S
orbitals are colored in black and the P
orbitals in green. Only a few orbitals
are represented in this sketch but there
can be many more. The valence electrons
can be easily identified as the
electrons in the orbital farther from
the nucleus they have higher energy and
are more easily employed to form
chemical bonds
