Video Transcript
Metals in group two commonly lose
electrons when forming bonds in chemical reactions. Once beryllium has lost two
electrons, how many electrons would be found in the outer shell?
Beryllium is an element in group
two of the periodic table. Atoms of beryllium have four
electrons. This diagram shows the electronic
configuration of an atom of beryllium. The first two electrons are located
in the K shell. The remaining two electrons are in
the L shell.
The problem tells us that atoms of
beryllium tend to lose two electrons. When atoms lose their electrons,
the electrons are lost from the outer electron shell. So atoms of beryllium will lose the
two electrons from the L shell, leaving two electrons remaining in the K shell.
This happens because atoms tend to
lose, gain, or share electrons to attain a stable electronic configuration. Generally, a configuration is
stable if there are two electrons in the K shell and eight electrons in the other
shells, like L, M, or N.
After beryllium loses two
electrons, there are two electrons left in the K shell and no electrons in the other
shells. So this electronic configuration is
stable. This question wants to know how
many electrons will be found in the outer shell after beryllium loses those two
electrons. In this case, the outer shell is
the K shell.
There are two electrons in the K
shell after beryllium loses two electrons. So two electrons is the correct
answer to this question.
