how can i determine the period number and group number of an element?

Answer 1

In a periodic table, the period number is the row number and the group number is the column number.

The periodic table is laid out according to how the electrons fill the atomic orbitals in an atom. The period is roughly how many layers of orbitals there are and the group number is roughly how full the top layer is. The noble gases at the ends of the row have a complete top orbital, and are very non-reactive. The elements just before and after tend to be very reactive, because they have only 1 electron too many or two few for the orbital. In general, the elements in the same group tend to have similar characteristics, because of the number of electrons in the top orbital.

Answer 2

I always use the electronic configuration of the element to determine those. This is how I do mine: let’s take for instance sodium Na. Having atomic # of 11.
Electronic config of Na = 2,8,1.
Now there are 3 digits i.e. 2,8 and 1, therefore the period # is three
And the group # is the determine by the last digit in this case one is the group #.

For aluminium: Al with 13 as the atomic # electronic config is 2, 8, 3.
Group # = 3
Period # = 3

This approach is true for all elements in the periodic table.

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Answer 3

By the number of protons in the atom. Element is defined by the number of protons so if you only have 1 proton then it is hydrogen, have 8 is a oxygen atom, etc.

Answer 4

Get a periodic table....you can find it on Yahoo....just print it