Question

Write formulas for the following compounds: (a) Nitrogen dioxide (b) Sulfur hexafluoride (c) Bromine triiodide (d) Dinitrogen trioxide (e) Nitrogen triiodide (f) Iodine heptafluoride

Short answer

(a) NO_2, (b) SF_6, (c) BrI_3, (d) N_2O_3, (e) NI_3, (f) IF_7

Step-by-step solution

Understanding Chemical Prefixes

Chemical prefixes indicate the number of each element in a compound. Common prefixes include: mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7). These prefixes help us write the correct chemical formula by specifying how many atoms of each element are present.

Writing the Formula for Nitrogen dioxide

The prefix 'di-' in 'dioxide' indicates there are two oxygen atoms. 'Nitrogen' implies one nitrogen atom (mono- is usually omitted). Therefore, the formula is \( NO_2 \).

Writing the Formula for Sulfur hexafluoride

The prefix 'hexa-' suggests six fluorine atoms. Sulfur, having no prefix, uses one atom. Thus, the formula is \( SF_6 \).

Writing the Formula for Bromine triiodide

The prefix 'tri-' signifies three iodine atoms. 'Bromine' suggests one atom. Thus, the formula is \( BrI_3 \).

Writing the Formula for Dinitrogen trioxide

The prefix 'di-' implies two nitrogen atoms, and 'tri-' signifies three oxygen atoms. Hence, the formula is \( N_2O_3 \).

Writing the Formula for Nitrogen triiodide

The prefix 'tri-' means three iodine atoms. Since 'Nitrogen' has no prefix, it implies one nitrogen atom. This yields the formula \( NI_3 \).

Writing the Formula for Iodine heptafluoride

'Hepta-' indicates seven fluorine atoms. With iodine having no prefix, we assume one atom. Thus, the formula is \( IF_7 \).

Key concepts

Chemical Prefixes

Chemical prefixes form an essential part of writing chemical formulas. These prefixes reveal the number of atoms of each element present in a molecule. They originate from Greek and Latin words, offering a standardized language in chemistry that helps convey the exact composition of compounds.
Understanding these prefixes is critical for interpreting and writing chemical formulas accurately. Some commonly used prefixes include:

• Mono-: Indicates one atom, though it is frequently omitted, especially when referring to the first element in the name.
• Di-: Means two atoms.
• Tri-: Refers to three atoms.
• Tetra-: Describes four atoms.
• Penta-: Signifies five atoms.
• Hexa-: Denotes six atoms.
• Hepta-: Indicates seven atoms.

These prefixes help in figuring out the number of atoms an element contributes to a compound, supporting the writing process of chemical formulas.

Writing Chemical Formulas

Writing chemical formulas is about translating the names of compounds into a representation that indicates their composition. This involves using chemical prefixes and the symbols of the elements involved.
To begin, identify the chemical prefix in the compound's name, which tells you the number of atoms of each element. This number is then written as a subscript next to the element's symbol in the formula.
For example, consider 'Nitrogen dioxide'. The prefix 'di-' in 'dioxide' tells us there are two oxygen atoms in the compound. The lack of a prefix for nitrogen indicates only one nitrogen atom. Thus, we write the formula as \( NO_2 \). Similarly, 'Sulfur hexafluoride' which contains the prefix 'hexa-', tells us there are six fluorine atoms, resulting in the formula \( SF_6 \).
By following these steps, you can confidently write chemical formulas by translating the compound name into its chemical representation.

Molecular Compounds

Molecular compounds are composed of molecules, which are collections of atoms bonded together. These compounds often consist of nonmetals. The way we name and write formulas for molecular compounds often involves using chemical prefixes to specify the number of atoms.
In molecular compounds, naming uses the full element name with a prefix for the first element, if more than one atom is present. The second element gets the '-ide' suffix, coupled with an appropriate prefix regardless of the number of atoms.
For example, in 'Bromine triiodide', the element bromine is written by its full name. The iodine is presented as "iodide", preceded by the prefix 'tri-' to indicate the presence of three iodine atoms. This translates into the formula \( BrI_3 \).
Molecular compounds show diverse chemical properties, but their naming and formula rules remain constant, easing the way they are studied and understood in chemistry.