Video Transcript
Which of the following is the
property of atoms of an element that reflects their strength of attraction to shared
electrons in bonds? A) Reduction potential, B)
Ionization energy, C) Electronegativity, D) Heat of combustion, or E) Activation
energy.
In this question, we’re being asked
to identify an atomic property, specifically, how strongly an atom will be attracted
to the shared electrons in a bond. When a bond is formed between two
atoms, it takes two electrons to create that bond. One electron is contributed by one
of the atoms participating in the bond, and the other electron is provided by the
other. These two electrons are then shared
between the atoms, which is what makes the bond between them. The way I’ve drawn this bond right
now, we have the electrons being shared pretty evenly between the two atoms
participating in the bond.
But we don’t always observe that
the electrons are shared evenly in a bond between atoms and a molecule. Sometimes one of the atoms has a
stronger attraction to the electrons than the other one does, which causes the
electrons to be pulled towards that atom. In this case, I’ve drawn the orange
atom as having a stronger attraction than the pink atom, so the electrons are closer
to the orange atom than the pink atom. This property that describes an
atom’s tendency to attract the shared bonding electrons towards itself is called
electronegativity.
In my example, the orange atom
would be more electronegative than the pink atom because it’s pulling more strongly
on these shared electrons between the two. Electronegativity increases as we
move to the right and up across the periodic table, with fluorine being considered
the most electronegative element. So, electronegativity is the
correct answer, as it’s the property of atoms of an element that reflects their
strength of attraction to shared electrons in a bond. But let’s go over the other answer
choices so we know what they are.
The reduction potential describes
the ability of a chemical species to be reduced. Reduction is what happens when a
chemical species gains an electron. When we’re talking about reduction,
we’re typically talking about something that’s occurring in an electrochemical
cell. In this case, one chemical species
would be reduced or lose an electron, and the other species would be oxidized or
gain an electron. This is known as a redox
reaction.
Ionization energy is the amount of
energy that’s needed to remove an outer electron from an atom. So, for example, if we were to
remove an electron from sodium, which would give us a positively charged sodium ion,
the energy that was required to remove that electron to give us the sodium ion would
be the ionization energy.
The heat of combustion is the
energy that’s released as a result of a combustion reaction. A combustion reaction is what
happens when we burn a chemical species in the presence of oxygen. A common example of this is when we
burn fuel in our cars, which creates carbon dioxide and water vapor. The energy that’s released as a
result of this combustion reaction is what powers the vehicles that we drive.
Our final answer choice is the
activation energy, which is the energy that’s needed for a chemical reaction to
occur. You’ve probably seen some kind of
reaction coordinate diagram like this before, where we have the reactants in one
spot and the products in the other. The activation energy, which I’ve
labelled E with a subscript A, is the amount of energy that’s needed to get over the
hump in this diagram so that the reaction can proceed.
But as we discussed earlier, the
property that this question is asking about is electronegativity, which is the
property of atoms of an element that reflects their strength of attraction to shared
electrons in bonds.
