How do I work out the electronic configuration of an element?

Question

I have to work out the electronic configuration for the alkali metals.

I would be very greatful if someone would show me how to work out the configuration of one of them so I can do the rest. :) Thanks

Answer 1

use the periodic table of elements. as a guide two electron on the innermost shell and 8 on subsequent shells for example oxygen has 16 electrons so the electron configuaration is 2:8:6 this also means it is in group 6 the number of electrons on the outer shell should be the same as the group.  another example is sodium 2:8:1 this means it is in group one

Answer 2

simply use a periodic table all e.c are already available

Answer 3

Do you have a periodic table? If so then...

Simply look at Group One (the first column) which are the alkali metals. As they are in the same group you know they all have the same number of electrons in the outer shell. Group one elements have one electron in the outer shell.

Next look at the periods (rows) this tells you how many shells an atom has. Period 3 elements all have 3 shells.

So if you take sodium, it is in period 3 so has 3 shells. Remember the 1st shell has a capacity of 2 electrons, and each after has 8. EAch shell must be full before the next shell can contain electrons.

So the electron configuration of sodium is 2:8:1

Now do the rest

Answer 4

look at it's atomic number

e.g oxygen=8

then electronic configuration would be...2, 6 or 1s2,2s2,2p4

e.g calcium=20

2,8,8,2 or 1s2,2s2,2p6,3s2,3p6,4s2