1. CuCl2 is an ionic compound.
QUESTION:
Which of the following is correct name for CuCl2? A. copper(II) chloride, B. copper(I) chloride C. copper chloride(II), D. copper(I) dichloride
CuCl2 is an ionic compound.
Cation is derived from copper. We must specify charge in roman numeral if cation is derived from a transition or post-transition metal. Copper(?)
Cl belongs to group VIIA. Anion is chloride: Cl-
The subscript 2 for Cl means that the total negative charge in one formula unit is –2.
Therefore the total positive charge in one formula unit must be +2. The cation is Cu2+, or copper(II).
SCRIPT:
Which of the following is correct name for CuCl2? A. copper(II) chloride, B. copper(I) chloride C. copper chloride(II), D. copper(I) dichloride
PAUSE
To name a compound given its formula, we need to first classify the compound, then apply the rule for that type of compound.
CLICK
CuCl2 is an ionic compound…. We know it’s ionic because copper is a metallic element and chlorine is a nonmetallic element.
Cations are generally derived from metallic elements, so we know that the cation in this compound is a copper ion.
Since copper is a transition metal, we have to specify its charge using a roman numeral in parentheses.
We can, therefore, eliminate choice C. In choice C, the charge of copper is not specified.
CROSS OUT choice C.
So, how do we determine the charge of the copper ion?
We look at the anion which, in this case, is derived from chlorine. By referring to a periodic table, we find that chlorine is a halogen --- it belongs
to group seven A. Therefore, we expect the monatomic ions derived from chlorine to have a –1 charge. Chloride ion is Cl with a –1 charge.
CLICK Since Cl has a subscript of two, this means that the total negative charge in one formula unit of this compound is –2. Two times –1 equals –2.
CLICK Therefore… the total positive charge in one formula unit must be +2.
Since there is no subscript written for copper, it’s implied to be one. Therefore, one copper ion in this compound must have a charge of +2.
The name of this compound is…
The name of the cation…. Copper two
HIGHLIGHT copper(II) in choice A
CROSS OUT copper(I) in choices B and D.
Followed by the name of the anion…. Chloride
HIGHLIGHT chloride in choice A
CROSS OUT di in dichloride (choice D)
CLICK PAUSE END RECORDING

2. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08