MediumChemistryHigh School (9–10)GeneralThe Periodic Table › Development of the Periodic TableConceptual
Six elements have these electron arrangements.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Six elements have these electron arrangements. A: 2, 8, 1. B: 2, 8, 8, 2. C: 2, 1. D: 2, 8, 2. E: 2, 8, 7. F: 2, 7. Which of them are in the same group? Which are in the same period?
Need a reminder? The key ideaShow
The modern table is ordered by atomic number: groups and periods holding , , , , , and elements. The period is the number of shells. Groups 1 and 2: group outer electrons. Groups 13 to 18: group outer electrons.
The worked solution
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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. Groups. A and C have one outer electron: group 1. B and D have two: group 2. E and F have seven: group 17.
Step 2. Periods. C and F have two shells: period 2. A, D and E have three: period 3. B alone has four: period 4.
Answer: groups: A and C; B and D; E and F. Periods: C and F; A, D and E.
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