Multiple Choice
Which of the following is the correct formula unit for the ionic compound formed when calcium combines with nitrogen?
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3. Chemical Reactions
Writing Ionic Compounds
Multiple Choice
Which of the following is the correct chemical formula for potassium oxide?
A
K2O
B
K2O2
C
KO2
D
KO
Verified step by step guidance1
Identify the charges of the ions involved: potassium (K) is an alkali metal in Group 1, so it forms a +1 ion (K\^{+}), and oxygen (O) typically forms a -2 ion (O\^{2-}).
To write the correct formula for an ionic compound, the total positive charge must balance the total negative charge, resulting in a neutral compound.
Since potassium has a +1 charge and oxygen has a -2 charge, determine the ratio of potassium ions to oxide ions needed to balance the charges. This means you need two potassium ions to balance one oxide ion.
Write the formula by placing the number of each ion as subscripts: two potassium ions and one oxide ion gives K\_{2}O.
Verify that the formula is electrically neutral: (2 \(\times\) +1) + (1 \(\times\) -2) = 0, confirming that K\_{2}O is the correct chemical formula for potassium oxide.
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