Chemical Naming & Formulas

1. What is the correct chemical formula for lead(II) acetate?

PbAc

Pb(C2H3O2)2

Pb(C2H3O2)4

PbC4H6O4

This compound contains no prefixes so you know its an ionic compound. Determine the symbol and charge of each ion and crisscross. The Roman Numeral after lead indicates the charge of the lead--Pb+2. Acetate ends in -ate and is therefore a polyatomic ion. Look it up on your polyatomic ion chart and you'll find C2H3O2 -1.

Explanation

This compound contains no prefixes so you know its an ionic compound. Determine the symbol and charge of each ion and crisscross. The Roman Numeral after lead indicates the charge of the lead--Pb+2. Acetate ends in -ate and is therefore a polyatomic ion. Look it up on your polyatomic ion chart and you'll find C2H3O2 -1.

2. What is the name of Ca(NO₃)₂?

If you see parentheses you know there is a polyatomic ion in the parentheses. Look up the name of that polyatomic ion (NO3 = nitrate). Then name the rest of the compound (Ca=calcium).

Explanation

If you see parentheses you know there is a polyatomic ion in the parentheses. Look up the name of that polyatomic ion (NO3 = nitrate). Then name the rest of the compound (Ca=calcium).

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3. Which of the following compounds is an acid?

BCl3

HNO3

H2O

C2H2

Acids are compounds that typically start with a H+ ion. Only two of these compounds start with H and one of them is water (which is neutral--not an acid).

Explanation

Acids are compounds that typically start with a H+ ion. Only two of these compounds start with H and one of them is water (which is neutral--not an acid).

4. What is the chemical formula of carbon tetrachloride?

Since this name has a prefix in it, you should recognize that it is a molecular compound. Use the prefixes to determine the chemical formula. Since carbon has no prefix there is only 1 carbon. Since chloride has the prefix tetra on it, we know there are 4 chlorine (chlorine with its ending changed to -ide).

Explanation

Since this name has a prefix in it, you should recognize that it is a molecular compound. Use the prefixes to determine the chemical formula. Since carbon has no prefix there is only 1 carbon. Since chloride has the prefix tetra on it, we know there are 4 chlorine (chlorine with its ending changed to -ide).

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5. What is the chemical formula of hydrofluoric acid?

Since the name states "acid" we know the compound starts with H. Acids are ionic compounds, so we need to get the symbol and charge of each ion. H+ is the first since it is an acid. Fluoric represents fluorine, F-. Crisscross the charges to get HF.

Explanation

Since the name states "acid" we know the compound starts with H. Acids are ionic compounds, so we need to get the symbol and charge of each ion. H+ is the first since it is an acid. Fluoric represents fluorine, F-. Crisscross the charges to get HF.

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6. What is the chemical formula for tin?

Sn

Ti

Sn2

Ti2

Tin is just an element and it is not one of the seven diatomic elements. Just write the symbol of the element.

Explanation

Tin is just an element and it is not one of the seven diatomic elements. Just write the symbol of the element.

7. What is the common name for dihydrogen monoxide?

Ammonia

Water

Carbon dioxide

Methane

Dihydrogen monoxide is H2O--water.

Explanation

Dihydrogen monoxide is H2O--water.

8. Which of these elements does not exist as a diatomic molecule?

Ne

F

H

I

There are 7 diatomic elements: H2,O2,N2,Cl2,Br2,I2,F2.

Explanation

There are 7 diatomic elements: H2,O2,N2,Cl2,Br2,I2,F2.

9. Ionic compounds that absorb water into their solid structure form

Nonpolar bonds

Molecules

Anhydrous substances

Hydrates

Hydrates absorb water.

Explanation

Hydrates absorb water.

10. What is the chemical formula of silver nitrate.

This compound is composed of a metal and nonmetals. Therefore, it is an ionic compound. You must get the symbol and charge of each ion (there's only one positive ion and one negative ion) and crisscross the charges.

The first ion is silver. Silver's symbol and charge is Ag+1. We know silver is +1 because silver is always +1.

The rest of the formula is therefore the 2nd ion--nitrate. Since it ends in -ate it is a polyatomic ion--look it up on your polyatomic ion chart. You'll find that nitrate is NO3 -1

Write both ions next to each other and then crisscross the charges down to subscripts to get AgNO3.

Explanation

This compound is composed of a metal and nonmetals. Therefore, it is an ionic compound. You must get the symbol and charge of each ion (there's only one positive ion and one negative ion) and crisscross the charges.

The first ion is silver. Silver's symbol and charge is Ag+1. We know silver is +1 because silver is always +1.

The rest of the formula is therefore the 2nd ion--nitrate. Since it ends in -ate it is a polyatomic ion--look it up on your polyatomic ion chart. You'll find that nitrate is NO3 -1

Write both ions next to each other and then crisscross the charges down to subscripts to get AgNO3.

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11. What is the ionic charge of the vanadium ion in the compound V₂O₅?

+2

-2

-5

+5

The easiest way to determine the charge of an ion in an ionic compound is to crisscross the subscripts back up to charges.

Explanation

The easiest way to determine the charge of an ion in an ionic compound is to crisscross the subscripts back up to charges.

12. What is the chemical formula of sodium oxide?

This compound contains a metal & a nonmetal and therefore is an ionic compound. Get the symbol and charge of each ion and crisscross. Sodium is Na+ and oxide is just oxygen with a negative charge or O-2.

Explanation

This compound contains a metal & a nonmetal and therefore is an ionic compound. Get the symbol and charge of each ion and crisscross. Sodium is Na+ and oxide is just oxygen with a negative charge or O-2.

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13. What is the name of the compound whose formula is NaC₂H₃O₂-9H₂O?

Sodium carbonate hydrate

Sodium acetate hydrate

Sodium dicarbon trihydride dioxide water

Sodium acetate nonahydrate

Sodium acetate nonawater

A compound with -H2O at the end is a hydrate and it's name ends in hydrate. Name the rest of the compound the same as usual--since Na is a metal, it's an ionic compound and there should be no prefixes.

Explanation

A compound with -H2O at the end is a hydrate and it's name ends in hydrate. Name the rest of the compound the same as usual--since Na is a metal, it's an ionic compound and there should be no prefixes.

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15. Name HBr.

Since this starts with H, assume it's an acid. It is a binary acid (it has 2 elements) so the name is hydro-root-ic acid. Since the element other than hydrogen is bromine the name is hydrobromic acid.

Explanation

Since this starts with H, assume it's an acid. It is a binary acid (it has 2 elements) so the name is hydro-root-ic acid. Since the element other than hydrogen is bromine the name is hydrobromic acid.

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16. What is the name for the compound FeS?

FeS is a metal and a nonmetal--it's ionic--NO PREFIXES. Name the metal (iron). Iron is a transition metal so we need to add a Roman numeral to indicate it's charge. Sulfur's charge is -2 so Iron must be +2 to cancel it out. Then name the nonmetal changing its ending to -ide (sulfide).

Explanation

FeS is a metal and a nonmetal--it's ionic--NO PREFIXES. Name the metal (iron). Iron is a transition metal so we need to add a Roman numeral to indicate it's charge. Sulfur's charge is -2 so Iron must be +2 to cancel it out. Then name the nonmetal changing its ending to -ide (sulfide).

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17. Name the compound N₂O₄.

The compound N₂O₄ is called dinitrogen tetroxide. It is an inorganic compound consisting of two nitrogen atoms (N₂) and four oxygen atoms (O₄). Dinitrogen tetroxide is a powerful oxidizer and is often used as a rocket propellant. It is a colorless liquid with a pungent odor and is highly reactive, especially with organic compounds.

Explanation

The compound N₂O₄ is called dinitrogen tetroxide. It is an inorganic compound consisting of two nitrogen atoms (N₂) and four oxygen atoms (O₄). Dinitrogen tetroxide is a powerful oxidizer and is often used as a rocket propellant. It is a colorless liquid with a pungent odor and is highly reactive, especially with organic compounds.

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18. What is the chemical formula of silicon dioxide octahydrate?

You should recognize that hydrate means that water is attached to the compound. Octa- means 8. Therefore, 8 H2O are attached to the compound. The name of the compound is silicon dioxide. Since silicon dioxide has prefixes, use the prefixes to determine the chemical formula. Silicon with no prefix means 1 Silicon. Di on oxide means 2 oxygen--SiO2.

Explanation

You should recognize that hydrate means that water is attached to the compound. Octa- means 8. Therefore, 8 H2O are attached to the compound. The name of the compound is silicon dioxide. Since silicon dioxide has prefixes, use the prefixes to determine the chemical formula. Silicon with no prefix means 1 Silicon. Di on oxide means 2 oxygen--SiO2.

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