Answers

2014-02-14T22:11:39+08:00
Number 20, the Calcium is No. 20.
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2014-02-14T22:11:44+08:00
Group 2 period 4... its atomic number is 20
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Wrong, the period is 4, not 3
oh yeah...i thought its 3...sorry.. at least i got the atomic number.,,. :)