Video Transcript
Which of the following metals is
less reactive than hydrogen? (A) Tin, (B) copper, (C) iron, (D)
sodium, (E) aluminum.
To answer this question, we need to
understand how to rank metals according to their reactivity. The reactivity of different
elements is typically ranked using what is known as a metal reactivity series. A reactivity series is a list of
metals and some nonmetals that are ranked according to their reactivity. Typically, the most reactive metal
is placed on top and the least reactive on the bottom.
A metal’s reactivity is defined as
the tendency of a metal to lose electrons and form positive ions. This means that the greater a
metal’s tendency to lose electrons, the more reactive its behavior. A metal’s reactivity is partly
influenced by the number of electrons in the outermost shell of an atom, known as
the valence electrons. The valence electrons can be
determined using the group number of a periodic table.
As a general rule, atoms towards
the lower-left corner of the periodic table are more reactive. And atoms towards the upper-right
corner are less reactive in terms of losing electrons. Fortunately, the reactivity series
is very common. So we will not need to manually
determine the reactivity of the metals in our question. Using some more advanced
electrochemistry, scientists have established a fixed order of reactivity, which is
used across the world as a reference.
The full reactivity series contains
a very large number of different elements and reactions. And we will look here at a simple
reactivity series of metals and choose the correct answer based on our question. As you can see from the reactivity
series, our five answer choices, including hydrogen for reference, are ranked in the
following order: sodium, aluminum, iron, tin, hydrogen, copper. Therefore, the only metal that is
less reactive than hydrogen is copper. The correct answer is copper.
