How to find the atomic number of an element on the periodic table with groups and periods?
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Answered by
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atomic no = No of electrons and protons
PERIOD NUMBER = NO. OF SHELLS
GROUP NO. = NO. OF VALENCE ELECTRONS
so when given the period no. and group no. you can easily find d out the atomic number using this formula
If this helps you please mark as brainliest
thanks
PERIOD NUMBER = NO. OF SHELLS
GROUP NO. = NO. OF VALENCE ELECTRONS
so when given the period no. and group no. you can easily find d out the atomic number using this formula
If this helps you please mark as brainliest
thanks
Answered by
0
Looking it up in the periodic table is the fastest way, because not all periods are equally long, and the groups are not always consecutive. The best I can give you is a piece-wise definition; given a period pp and a group gg, the atomic number nn is given by:
p=1p=1, g=1g=1: n=1n=1
p=1p=1, g=18g=18: n=2n=2
p=2p=2 or p=3p=3, g≤2g≤2: n=8p+g−14n=8p+g−14
p=2p=2 or p=3p=3, g≥13g≥13: n=8p+g−24n=8p+g−24
p=4p=4 or p=5p=5, n=18p+g−54n=18p+g−54
Further down, you'll have to account for the rare earth elements which don't even have a group.
p=1p=1, g=1g=1: n=1n=1
p=1p=1, g=18g=18: n=2n=2
p=2p=2 or p=3p=3, g≤2g≤2: n=8p+g−14n=8p+g−14
p=2p=2 or p=3p=3, g≥13g≥13: n=8p+g−24n=8p+g−24
p=4p=4 or p=5p=5, n=18p+g−54n=18p+g−54
Further down, you'll have to account for the rare earth elements which don't even have a group.
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