In the periodic table there is 2 numbers next
to each element eg 5 X 8
How do you work out the number of electrons useing
these numbers?
Different versions of the periodic table will show
different information in the little boxes of each element. So it
depends on whichever one you are using. There should be a key with
the table to explain what the numbers mean - I have seen versions
with four numbers in each box! Try looking at www.webelements.com
for their version. Initially there is only the one number in their
boxes - but when you click on the box of the element of your choice
you get lots more information about it. The first number is always
the ATOMIC NUMBER and this is the number of protons in the nucleus.
This is the thing which makes the atom an atom of whatever it is
- change this number and it won't be the same atom anymore. It is
this number which also equals the number of electrons the atom normally
has. The other number that is often mentioned (at least twice as
big or more often more than twice as big) is called the MASS NUMBER
and this is the number you get when you add the number of protons
in the nucleus and the number of neutrons in the nucleus together.
This number is no use when trying to work out the number of electrons
but is useful if you want to work out how heavy the atom is.
Brian
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