Video Transcript
An ion has the symbol notation
Be2+. How many electrons have been lost
or gained to form this ion? (A) Two lost, (B) two gained, (C)
one lost, (D) one gained.
Atoms are neutrally charged
particles that have an equal number of negatively charged electrons and positively
charged protons. Ions, however, are charged
particles with an unequal number of electrons and protons. Atoms can become ions by gaining or
losing electrons. If an atom gains an electron, then
the number of negatively charged electrons will be greater than the number of
positively charged protons. The species will be negatively
charged overall and is called a negative ion. If an atom loses an electron, then
the number of negatively charged electrons will be less than the number of
positively charged protons. The species will be positively
charged overall and is called a positive ion.
In symbol notation, the charge of
the ion is written as a superscript to the right of the element symbol. As the given symbol notation shows
a positive charge, we know that this is a positive ion and that electrons have been
lost to form it. Each electron has a single negative
charge, and each proton has a single positive charge. So in order for an ion to have a
charge of positive two, a neutral atom must have lost two negatively charged
electrons.
Therefore, the number of electrons
that have been lost or gained to form the Be2+ ion is answer choice (A), two
lost.
