Video Transcript
Scientists combine sodium metal
with chlorine gas to produce a sodium chloride compound. The reaction can be described with
the equation two Na solid plus Cl2 gas makes two NaCl solid. Which of the following diagrams
shows how the chlorine molecules combine with electrons during this chemical
reaction? (A) Chlorine Cl2 plus two e− makes
two Cl−. (B) Chlorine Cl2 plus two e− makes
one Cl−. (C) Chlorine Cl plus two e− makes
two Cl−. (D) Chlorine Cl plus two e− makes
one Cl−. (E) Chlorine Cl2 plus one e− makes
two Cl−.
Sodium metal reacts with chlorine
gas when the temperature is high enough. Sodium atoms lose a single electron
during this chemical reaction. One electron moves from each sodium
atom to a chlorine atom. The figure shows how an electron
moves between atoms during this chemical reaction. The sodium atom starts with the
2,8,1 configuration before the chemical reaction. It then loses an electron to a
single chlorine atom. The neutrally charged sodium atom
turns into a one-plus charged sodium ion that has the 2,8 electronic
configuration.
The chlorine atom has a 2,8,7
electronic configuration before the chemical reaction. It turns into a negative-one-state
chloride ion when it gains an electron from a sodium atom. The ion has the 2,8,8 electronic
configuration after the electron transfer process. There is an electrostatic
attraction between the oppositely charged ions. They bond and make the sodium
chloride compound. Each chlorine atom gains a single
electron when it reacts with sodium.
One neutrally charged chlorine atom
turns into one negatively charged ion when it gains one electron. The chloride ion has the negative
one charge state after the electron transfer process. Since chlorine exists as Cl2
molecules, we would need to double the equation shown here. Let’s keep this in mind when
returning to the answer choices.
Options (C) and (D) are not
correct. They show one chlorine atom
combining with two electrons. Option (E) is not correct
either. It shows two chlorine atoms
combining with a single electron. Option (B) is incorrect as
well. It shows one negatively charged
chloride ion formed as two electrons combine with a single neutrally charged
chlorine molecule. Options (B) through (E) are all
incorrect.
Option (A) correctly describes how
chlorine combines with electrons during a reaction with sodium. It has each chlorine atom turning
into a single chloride ion when it combines with a single electron. The equation shows two electrons
and two chloride ions because chlorine gas is a diatomic molecule.
Option (A) is the correct answer to
this question. The correct answer is “chlorine Cl2
plus two electrons makes two Cl−.”
