Improve your understanding of chemical orbitals
Orbital ooh! It is like orbit and orbit is something
round ooh! Not round but spherical. Sometime differentiating round and sphere
can be like climbing a steep mountain to majority of human kind. Back to
business, it will be very crucial to understand what a shell is and the number
of shells which are possible in an atom.
Shell is a spherical space around a nucleus (nucleus of an atom consists
of protons and neutrons, except for one of the hydrogen isotopes (protium),
which has a nucleus consisting of one proton. The nucleus has a positive
electric charge, the size of which depends upon the number of protons it
contains. The nucleus provides the mass of an atom); it contains extra-nuclear
electrons with energy levels of that shell. An atom possesses different shells
of increasing radii around its nucleus. The radius of a shell is 100 000 times
greater than the radius of the nucleus.
Ok now let’s focus on these shells of atom. The first
one is; K-shell is the innermost atomic shell, it contains only one s-orbital
(contains only two (2) electrons). This arrangement completes the shell. This is
followed by L-shell which is the next atomic shell to the K-shell; it contains
one s-orbital and three p-orbitals that is px, py and pz which contain 2
electrons each (a total of 8 electrons) and this arrangement completes the
shell. M-shell is the third shell it is the next atomic shell to the L-shell, it
contains one s-orbital, three p-orbitals and five d-orbitals. This means it
contains a total of 18 electrons. This arrangement
completes the shell. There are further shells beyond the M-shell and they
include: N-shell which is the next atomic shell to M-shell, it contains one
s-orbital, three p-orbitals, five d-orbitals and seven f-orbitals thus contains
a total of 32 electrons. The next one is O-shell it is the next atomic shell to
the N-shell. This contains one s-orbital, three p-orbitals, five d-orbitals and
seven f-orbitals and nine g-orbitals this makes it to accommodate a total of fifty
(50) electrons. The final one is P-shell this next to atomic O-shell. It
contains one s-orbital, three p-orbital, five d-orbitals, seven f-orbitals, and
nine g-orbitals and finally eleven h-orbitals. This means it contain a total of
72 electrons.
Now orbital can be understood with easy. Orbital is
the space where one or two electrons but not more can exists. The space is
where there is a probability of finding one or both electrons. The probability
varies over the space, and can be shown in various ways by a diagram. The
position and motion of an electron in an orbital cannot be described, only the
probability can be described. One way of showing probability is by shading.
Another way is by drawing the limits of the orbital, two electrons in an
orbital do not interfere with each other; two electrons form a stable orbital,
while one electron in an orbital is active in forming chemical bonds. The
orbitals commonly taking part in bonds are s-, p- and d-orbitals even though in
the above paragraph more of them are addressed. The best way to know the number
of orbitals a shell can hold and the number of electrons and orbital can hold
is by this;the number of electrons in one orbital to another increases by 4
electrons, for instance s-orbital can
hold 2 electrons while p-orbital can hold 6 electrons. From s-orbital to
p-orbital, there is increment of 4 electrons (2+4=6 electrons which occupy
three p-orbitals). This is the same with all succeeding orbitals.To get the
number of orbitals in a given level of orbital is by adding 2 to the previous
level of a given orbital. For example from s-orbital to p-orbital there is addition
of 1+2 = 3, and this result in three p-orbitals. This is true from p-orbital to
d-orbital, where 3+2 = 5, this results in five (5) d-orbitals. The number of
orbitals a shell can contain is achieved by; linear arithmetic progression.
From K-shell to L-shell, the orbitals increase by 3. This means L-shell can
contain 4 maximum numbers of orbitals (one s-orbital and three p-orbitals). The
shell (M-shell) can contain nine (9) numbers of orbitals. Therefore you can use
linear arithmetic progression to obtain the number of orbitals a shell can
contain in that order. Let’s demonstrate by an example K-shell (1) = L-shell
(4) = M-shell (9), in the first difference we have 3, to get the next
difference you should add 2 to get 5, now, 4+ 5 = 9. This you can do to the
next atomic shell by adding 2 +5 to get seven (7) then seven
(7) plus 9 yields 16. Thus the next shell can hold 16 orbitals. Take a look at
example below:
Orbital Maximum
number of electrons Shape
s (sharp) 2 Spherically symmetrical
p (principal) 6 Px , Py ,Pz
d (diffuse) 10 5 orientations
f (fundamental) 14 7 orientations
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