Naming Binary Molecules

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Questions and Answers

What is the correct order of elements in the formula for a binary molecule when both elements are in the same group in the periodic table?

Alphabetical order of the elements

Random order, as long as the elements are in the same group

Lightest element first, heaviest element second

Heaviest element first, lightest element second (correct)

Why is the molecule ClO3 written as such, rather than O3Cl?

Because O should always be at the last in the formula, according to the naming rule for anions (correct)

Because Cl is the first element in the periodic table

Because O is the heaviest element

Because Cl is the lightest element

What is the correct name for the molecule NF3?

Mononitrogen trifluoride

Nitrogen trifluoride (correct)

Nitrogen monofluoride

Nitrogen fluoride

Why is the prefix 'mono-' dropped in the name of the molecule Cl2O?

Because the name of the second element begins with a vowel Signup and view all the answers

What is the correct name for the molecule N2O4?

Dinitrogen tetroxide Signup and view all the answers

Why is the molecule SO2 written as such, rather than O2S?

Because S is heavier than O, and should be written first Signup and view all the answers

What is the correct suffix for the second element in a binary molecule?

-ide Signup and view all the answers

Why is the prefix 'mono-' not used for the first element in a binary molecule?

Because the prefix 'mono-' is not necessary for the first element Signup and view all the answers

What is the correct suffix for the nitrate ion?

-ate Signup and view all the answers

Which of the following oxyanions does not have an –ite counterpart?

Carbonate ion Signup and view all the answers

What prefix is added to the oxyanion with one oxygen more than the common?

per- Signup and view all the answers

What is the correct name for the sulfite ion?

Sulfite ion Signup and view all the answers

Which of the following oxyanions can be extended to form four members?

Chlorate ion Signup and view all the answers

What prefix is added to the oxyanion that is one oxygen less than the –ite version?

hypo- Signup and view all the answers

What is the correct suffix for the sulfate ion?

-ate Signup and view all the answers

Which of the following is a common mistake in chemical naming?

Using the suffix -ate for the nitrite ion Signup and view all the answers

What is the correct name for the ion ClO$^-$?

Hypochlorite ion Signup and view all the answers

Which prefix is used for an anion derived by adding one hydrogen ion to the phosphate ion?

Hydrogen- Signup and view all the answers

Which of the following correctly describes the naming of anions formed by adding hydrogen ions to common oxyanions?

They use the prefix 'hydrogen' for one hydrogen added. Signup and view all the answers

What is the overall charge of an ionic compound formed from Na$^+$ and ClO$^-$?

Neutral Signup and view all the answers

What is the correct way to write the formula for sodium bicarbonate?

NaHCO$_3$ Signup and view all the answers

Which of the following oxyanions corresponds to the formula ClO$_2^-$?

Chlorite ion Signup and view all the answers

If an anion is referred to as 'dihydrogen phosphate', what does this imply about its composition?

It contains two hydrogen ions. Signup and view all the answers

Which of the following represents a common misconception in chemical naming?

Naming ClO$^-$ as chlorate instead of hypochlorite. Signup and view all the answers

Study Notes

Writing Binary Molecules

In a binary molecule, the elements are written in a specific order, with the heavier element first.
If both elements are in the same group in the periodic table, the heavier element is written first.
Oxygen is always written last, following the naming rule for anions.

Rules in Naming Binary Molecules

The second element in a binary molecule is named with an ending –ide.
The number of the second element is indicated using Greek prefixes: mono-, di-, tri-, etc.
If the second element's name begins with a vowel, the 'a' or 'o' in the prefix is dropped.
The mono- prefix is not used for the first element.

Examples of Naming Binary Molecules

NF₃ is named Nitrogen trifluoride.
Cl₂O is named Dichlorine monoxide (not monooxide, with the 'o' dropped).
N₂O₄ is named Dinitrogen tetroxide (not tetraoxide).

Naming Anions

Anions derived from oxyanions by adding H⁺ are named by adding the prefix hydrogen-, bi-, or dihydrogen.
Examples: • CO₃²⁻ + H⁺ → HCO₃⁻ (hydrogen carbonate or bicarbonate). • PO₄³⁻ + H⁺ → HPO₄²⁻ (hydrogen phosphate or biphosphate).

Common Oxyanions

The following oxyanions must be memorized: • CO₃²⁻ (carbonate ion). • NO₃⁻ (nitrate ion). • PO₄³⁻ (phosphate ion). • SO₄²⁻ (sulfate ion). • ClO₃⁻ (chlorate ion).

Extended Oxyanions

Some oxyanions can be extended to form four members by adding prefixes: • per- for one oxygen more than the common oxyanion. • hypo- for one oxygen less than the –ite version.

Formula of Ionic Compounds

Ionic compounds are formed by combining cations and anions in the right proportion to have no charge in the final form.
The suffixes -ate and -ite are used to indicate the common and one oxygen less than common oxyanions, respectively.

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Description

Learn the rules for naming binary molecules, including the order of elements, use of Greek prefixes, and naming anions. Examples of nitrogen and chlorine compounds are provided.