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Rules for writing Electronic Notation Below this table!
ORBITAL NOTATION/CONFIGURATION: HOW DO I...?
To accomplish this task you need:
+Periodic Table (above)
+Orbital Color code guide (right)
Before you start you should know:
Each row = energy level
Rows have sub-levels called s, p d or f. The chart to the right shows you the order where electrons will fall into specific sub-levels. Sub-levels are the spaces that electrons exhibit. We don't know what that actually looks like right now and that's okay (coming later).
Now Look at the chart to the right, notice the s, p, d, f sections →
How to:
- Electronic configurations is like working a board game. The periodic table is your board. As you move across, each box represents the addition of one more electron.
A problem will look like this:
"What is the electronic configuration of Oxygen?"
Using the color code guide (right) and a periodic table (above) you will be moving across the table keeping a tab on where you have been and how many electrons you have (each box you pass will represent 1 electron).
Rules as you move across the table.
- Start at #1 work your way across.
- Record each energy level (Each Row is an energy level), from the top down 1, 2, 3, 4, 5, 6, 7 (or look at the chart on the right)
(notable exception: that the d level starts at 3 even though it is level 4, this will be explained later)
- Record each sub-level is as you move across the table. Sub levels (s, p, d, or f) are separated by commas:
- Record how many electrons (boxes) you go through as you go through each sublevel as a superscript.
Example: He: 1S2
orbital color code guide:
Video: How to write electron configurations:
Now back to the original question: " What is the electronic configuration of Oxygen?"
Count across the periodic table to oxygen, stop after each sub-level (s, p, d, or f)
Oxygen
O: 1S2, [done with this row, go on to the next row and continue]
O: 1S2, 2S2, 2P4 [final answer]
Notice each sub level is spaced with a comma ,
Still not sure what's going on here? Look at the color code to the right and match them up with the terms below! → → →
Oxygen:
O: 1S2, [done with this row, go on to the next row]
O: 1S2, 2S2, 2P4 [final answer]
The number in the beginning = the energy level with the exception of the d orbital, these from the top down are 1, 2, 3, 4, 5, 6, 7 (you can see these in the color guide above)
Letter that comes after the energy level = this is the sub level. This is matched from the orbital color code guide.
Superscript= This is the number of electrons from that sub level. To find this count the number of boxes it takes to get to the element you are seeking. Each box adds to this subscript. Note: When you move on to a new sub level this number goes back to zero.
In the case of oxygen:
O: 1S2, 2S2 you move all the way through these S orbitals to get to oxygen (#8 on the p. table) so they both get a 2 because there are two boxes (if you look at your color guide).
2P4 p sub level only gets 4 electrons because you stop at the fourth box in that sub level (so it winds up only being partly filled).
O: 1S2, 2S2, 2P4
At this point the full configuration is done. Congrats!
For practice try writing the configuration for these fancy elements:
(link below to check your answers)
boron (B)
Arsenic (As)
(you really know your stuff if you got Arsenic right!)
Hydrogen (H)
Copper (Cu)
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