Video Transcript
Which of the following metals has
the strongest metallic bonding? (A) Sodium, (B) lithium, (C)
beryllium, (D) magnesium, or (E) aluminum.
This question is asking us to find
the strongest metallic bond. The strongest bond is the one that
has the strongest attractions between the particles. There are two key characteristics
that can affect the strength of the attractions from metal to metal. First, the more valence electrons
that a metal has, the stronger the bond. The extra electrons will add to the
overall attractive forces acting on the positive ions. The other relationship that could
come into play is that, in general, more electron shells means a weaker bond,
although there are many exceptions to this pattern.
The separation between the nucleus
and the valence electrons that the extra electron shells provide weakens the
attractive forces between the positively charged and negatively charged
particles. However, this second relationship
is not as strong as the relationship between valence electrons and bond
strength. So, let’s investigate that
relationship first by finding the number of valence electrons of each of these
metals. How do we find the number of
valence electrons? Well, we can take a look at the
periodic table.
As members of group one, sodium and
lithium have one electron in their outermost electron shell or one valence
electron. One column to the right, we find
beryllium and magnesium in group two with two valence electrons. Aluminum, the third element in its
row in group 13, has three valence electrons. Since it has the most valence
electrons, aluminum, choice (E), is the correct answer. In the case of aluminum, each
positive ion has more negative electrons around it, leading to more attractions and
a stronger bond.
In this problem, we did not end up
using the second relationship between the number of electron shells and the bond
strength. If there were multiple metals that
were tied for the highest number of valence electrons among the choices, we could
use this second relationship as a sort of tiebreaker. However, since there are many
exceptions to this pattern, it would be useful to confirm any assumptions about bond
strength or melting points gleaned from this pattern by looking them up. Of the choices, the metal with the
strongest metallic bonding is choice (E) aluminum.
