Mixed Ionic and Covalent Naming and Formulas

What is the name of : Na₂S

• sodium sulfur

• sodium sulfide

• sodium sulfate

• disodium monosulfide

• sodium sulfite

Answer explanation

Name the cation first. If it is a transition metal, you would write a charge but it is not required in this class. If the anion is made of only one element, change the ending to -ide. If the anion is a polyatomic ion, copy the name exactly as it appears on your polyatomic ion sheet. Do NOT use prefixes!

What is the chemical formula for potassium chloride?

• ClK

• KCl₂

• KCl

• K₂Cl₂

• K₂Cl

Answer explanation

The metal cation is written first, the non-metal anion is written last. Balance the charges!

What is the chemical formula for lithium sulfate??

• LiS

• LiSO₄

• Li₂SO₄

• Li(SO₄)

• Li₂(SO)₄

Answer explanation

The metal cation is written first, the non-metal anion is written last.

Balance the charges!

If you need more than one copy of a single ion, write the number after the ion. If you need more than one copy of a polyatomic ion, you need parentheses.

What is the chemical formula for Magnesium nitrate?

• MgN

• MgNO₃

• Mg₂NO₃

• Mg(NO₃)₂

• Mg₂(NO)₃

Answer explanation

The metal cation is written first, the non-metal anion is written last.

Balance the charges!

If you need more than one copy of a single ion, write the number after the ion. If you need more than one copy of a polyatomic ion, you need parentheses.

Which of the following is the correct name for C₄S₃?

• carbon sulfur

• carbon sulfide

• carbon sulfite

• tetracarbon trisulfide

• trick question; the charges don't balance so this isn't a real compound

Answer explanation

2 non-metals, so this is a covalent compound. Name both elements, then use prefixes to tell how many atoms there are of each element. The prefixes are listed on your polyatomic ion sheet

According to the rules that we learned in class, what is the name of C₃H₈?

• carbon hydrogen

• carbon hydride

• carbon (III) hydride

• tricarbon octahydride

• propane

Answer explanation

2 non-metals, so this is a covalent compound. Name both elements, then use prefixes to tell how many atoms there are of both elements

What is the chemical formula for phosphorus trioxide?

• P₂O₃

• P₃O

• PO₂

• PO₃

• PO

Answer explanation

2 non-metals, so this is covalent. Write the symbols for both elements, then use the prefixes to determine how many atoms there are for both elements

What is the chemical formula for aluminum nitrate?

• AlN

• Al(NO)₃

• AlNO₃

• Al₃NO₃

• Al(NO₃)₃

Answer explanation

Remember that when you write a polyatomic ion, you have to copy it EXACTLY the way you see it on your polyatomic ion sheet, including copying all of the numbers exactly the way you see them.

Balance the charges! If you need more than one copy of a polyatomic ion, you must put parentheses around the polyatomic ion and then put a subscript number on the outside.

Which of the following is the correct name for Fe₂O₃?

• iron oxide

• iron dioxide

• diron trioxide

• iron trioxide

• iron(III) oxide

Answer explanation

Name the cation first. If it is a transition metal, you would write a charge but it is not required in this class. If the anion is made of only one element, change the ending to -ide. If the anion is a polyatomic ion, copy the name exactly as it appears on your polyatomic ion sheet. Do NOT use prefixes!

What is the name of the compound with the formula NH₄Cl?

• ammonium chloride

• ammonium chlorate

• tetrammonium chloride

• nitrogen hydrogen chloride

• ammonium chlorine

Answer explanation

Name the cation first. If it is a transition metal, you would write a charge but it is not required in this class. If the anion is made of only one element, change the ending to -ide. If the anion is a polyatomic ion, copy the name exactly as it appears on your polyatomic ion sheet. Do NOT use prefixes!