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Fleetron Configu rations and Orbital Diagrams

irding t Qt m Mechanical model of the atom every electron of an atom is described by four quantum munbeis I he auantum raimbe    scribe the orbitals that theeiectrons are located in Each

orbital has o unique sLre(n valueX shape (1 \ahie), and . orientationim, value) Eachorbitalcan hołd at most two eiectrons, with .1 •... orbital having twoelectronu whh if( pindiir<tion(m, value). The locationof the eiectrons within the \    01    is cpresscd by orbital diagrams

and electron configuration symboli

f lec trons fili the orbitals of an atom starting with the lowest cncrgy lcvcl < Ince each orbital at the same cncrgy sublevcl is filled, ck*< trons bogiń filling the orbitals of the im rgy 8ublevci rhe ordering of

the energy of the ynrious orbital types ^,s shown in the diagram at the

5p___ leli It might be surprtsing to obscrv e

4,1_____ that the 4s orbitals of matom have

slightK■ Iow er enerj    uithc3d

orb al While they are v en dose in energy, the 4s orbital is słightly lower tn energy. The diagram at the right represents a com-cnient w ay of rememhering the order in which the orbitals fili Simply follow the arrows begimung with the lowest one A finał nile for filling orbitals with eiectrons is that each orbital at the same energy sublewl must have an electron befon* eiectrons begin painng up inside the same orbital. thi" is know n is Hunds nile

^łP

u

'p

u

>p

}%

I*

lincrgjr

r

fo

As

26

U

⁴P

3p

2p

hd

4d

3d

\

hf

4f

The diagram bel o w represents the so-called orbital diagram for c hromium I he 24 eledrons ot a mium atom will fili each of tłu ni< rbitals in tnc mannci !

El

ls

"I

2s

niEE

2p

		E
n ti	\n\	4s
3p

EEEEE ^DS^[

3d

An orbital diagram naturally leads to the writing of an electron configuration The electron configuration for cluomium is:

ls^:l«r'2p^s*3p'4s'3d'

Tl** orbital diagram above »formatted in sucha manner as topiące the various orbital types at different energy levełs A similar format that is used in tłu textbook (and serves to save space) is the format below in which the orbitals are listed in order ol their energies but along the same linę