Video Transcript
The atomic numbers of a selection
of elements are shown in the table below. An energy level diagram showing the
electronic configuration of an atom is also shown. What is the identity of the
atom?
An electronic configuration, which
we are given in the diagram, indicates the distribution of electrons in energy
levels. The energy levels are labeled K, L,
M, N in the diagram. Energy levels are the distances
from the nucleus that describe the location of electrons. For each energy level, we are told
the amount of electrons present. Therefore, the electronic
configuration of the unknown atom is two, eight, four.
We can calculate the total number
of electrons by adding the number of electrons present in each energy level. By adding two, eight, and four, we
calculate 14. This means the total number of
electrons present in the atom is 14.
We are also given the atomic
numbers of several elements. The atomic number of an element
tells us the number of protons it contains. This also indicates the number of
electrons for a neutral atom. For an atom to be neutral, the
number of positively charged protons must be equal to the number of negatively
charged electrons.
We know that the atom has 14 total
electrons. We know that this neutral atom must
also have 14 protons. This means the identity of the atom
must have an atomic number of 14. The atom is an atom of silicon. Therefore, the identity of the atom
with the electronic configuration shown is silicon.
