EasyChemistryHigh School (9–10)GeneralStructure of the Atom › Electronic Configuration and ValencyNumericalBoard Exam
Write the electron arrangement of boron (Z = 5), phosphorus (Z = 15) and calcium (Z = 20)…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Write the electron arrangement of boron (), phosphorus () and calcium (). How many shells does each atom use?
Need a reminder? The key ideaShow
Shell holds at most electrons, and the outermost shell holds at most . Fill the shells from the inside: for the first twenty elements, in K, up to in L, up to in M, and the rest in N.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Boron. in K, left for L: . Two shells.
Step 2. Phosphorus. in K, in L, left for M: . Three shells.
Step 3. Calcium. , , , and left for N: . Four shells.
Answer: ; ; .
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