Unit 5 - Mark Rosengarten

3) Orbital (Box) Diagrams: tells you how many electrons are in each ORBITAL of each sublevel, and what each
electron’s SPIN is. Sublevels are broken down further into orbitals, much as streets of a town can be broken down into
individual houses. Just as different sized streets can have different numbers of houses on them, the more electrons a
sublevel can hold, the more orbitals it can be broken down into. Orbitals are all the same size, they can all fit up to two
electrons in them. The electrons in the orbitals spin, much like the Earth about its axis. The spin of electrons is
indicated by arrowsup and down. If there is only one electron in the orbital, it will have an up spin. If the orbital has
two electrons in it, the first will have an up spin, and the second will have a down spin.
Orbitals are represented as boxes, into which one or two arrows may be placed. The electrons fill the orbitals of each
sublevel in a special order. First, all of the up arrows are placed in each box, followed by the down arrows. The
number of arrows will equal the number of electrons in the sublevel.
RULES:
1) The number of orbitals is equal to half the number of electrons each sublevel can hold.
Sublevel
Type
Number of
Electrons
s 2 1
p 6 3
d 10 5
f 14 7
Number of
Orbitals
What each sublevel’s orbitals looks like, filled with electrons
One box, filled with two arrows, one up, one down
Three boxes, each filled with two arrows (total of 6 electrons)
Five boxes, each filled with two arrows (total of 10 electrons)
Seven boxes, each filled with two arrows (total of 14 electrons)
2) When two electrons occupy the same orbital, they must have opposite spin. When electrons fill the boxes,
the UP arrows go in first.
An orbital with one electron in it looks like:
An orbital with two electrons in it looks like:
The sublevel name (1s, 2p, etc) is written above each set of orbitals.
Lithium’s shell configuration is 2-1. Sublevel: 1s 2 2s 1
Box Diagram:
1s
2s
© 2011, Mark Rosengarten R 12