Open Question
Consider the following Lewis symbols for elements X and Y: (6.1, 6.2, 6.5) e. What would be the formula of a compound of X and sulfur?
3. Ionic Compounds
Writing Formula Units of Ionic Compounds
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Provide the molecular formula for the following compound:Sodium dichromate
A
NaCr2O7
B
Na(Cr2O7)2
C
NaCrO4
D
Na2Cr2O7
E
Na2CrO4
Verified step by step guidance1
Understand the composition of sodium dichromate: it consists of sodium (Na), chromium (Cr), and oxygen (O).
Recognize that sodium dichromate is a compound where the dichromate ion (Cr2O7) is paired with sodium ions.
Recall that the dichromate ion has a formula of Cr2O7 with a charge of -2.
Determine the number of sodium ions needed to balance the charge of the dichromate ion. Since each sodium ion has a charge of +1, two sodium ions are required to balance the -2 charge of the dichromate ion.
Combine the sodium ions with the dichromate ion to form the molecular formula: Na2Cr2O7.
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Related Practice
Open Question
Using each of the following electron arrangements, give the formulas for the cation and anion that form, the formula for the compound they form, and its name. (6.2, 6.3)
