Question

Write the formula for each of the following compounds containing a semimetal. (a) boron tribromide (b) trisilicon tetranitride (c) diarsenic trioxide (d) diantimony pentaoxide

Short answer

(a) BBr₃, (b) Si₃N₄, (c) As₂O₃, (d) Sb₂O₅.

Step-by-step solution

- Understanding Semimetals

The compounds listed include a semimetal (also called a metalloid), such as boron, silicon, arsenic, and antimony. Semimetals have properties of both metals and non-metals and are found in the periodic table between metals and non-metals.

- Interpreting the Names of Compounds

Each compound name lets us know how many atoms of each element are present. For example, 'tri-' means three, 'tetra-' means four, 'di-' means two, and 'penta-' means five.

- Writing the Formula for Boron Tribromide

The prefix 'tri-' indicates three bromine atoms. Hence, for boron tribromide, the formula is BBr₃.

- Writing the Formula for Trisilicon Tetranitride

The prefix 'tri-' means three silicon atoms, and 'tetra-' means four nitrogen atoms. Therefore, the formula for trisilicon tetranitride is Si₃N₄.

- Writing the Formula for Diarsenic Trioxide

The prefix 'di-' means two arsenic atoms, while 'tri-' indicates three oxygen atoms. Thus, the formula for diarsenic trioxide is As₂O₃.

- Writing the Formula for Diantimony Pentaoxide

The prefix 'di-' means two antimony atoms, and 'penta-' indicates five oxygen atoms. Therefore, the formula for diantimony pentaoxide is Sb₂O₅.

Key concepts

Semimetals

Semimetals, also known as metalloids, are elements that have properties of both metals and non-metals. They can be found on the periodic table along the dividing line between metals and non-metals. Semimetals are quite unique; they often display metallic luster while having the brittle nature of non-metals.

Examples of semimetals include boron, silicon, arsenic, and antimony. These elements are crucial in forming various compounds because they can bond with other elements in different ways, showcasing their hybrid properties. This ability to bridge the characteristics of metals and non-metals makes them particularly valuable in electronics and materials science.

• They are good conductors of electricity, but not as good as metals.
• They are more brittle than metals, making them similar to non-metals.
• They often form covalent bonds, typical of non-metals.

Understanding the nature of semimetals helps predict how they interact in compounds, which is essential when writing or interpreting chemical formulas.

Compound Nomenclature

Compound nomenclature is the systematic way of naming chemical compounds. It tells us the exact makeup of a compound in terms of the elements involved and the number of atoms of each. This system uses specific prefixes derived from Greek or Latin to indicate quantities.

For instance, the prefixes in chemical nomenclature give us clues about the number of each type of atom present in a compound:

• 'Mono-' stands for one (though often omitted in the first element).
• 'Di-' means two.
• 'Tri-' is three.
• 'Tetra-' indicates four.
• 'Penta-' stands for five.

When reading a compound's name, these prefixes tell us exactly how many atoms of each element are present. For example, in "boron tribromide", the prefix 'tri-' indicates three bromine atoms are present.
Successfully interpreting these names is key to correctly writing their chemical formulas.

Chemical Compounds

Chemical compounds are substances formed when two or more elements are chemically bonded together. These bonds can be ionic, covalent, or metallic, depending on the nature of the elements involved. Compounds are characterized by fixed ratios of each type of atom, represented by their chemical formulas.

In the context of semimetals:

• Covalent bonds are more common, as semimetals often share electrons to achieve stability.
• The formula of a compound indicates both the types and numbers of atoms.
• Applying the rules of chemical nomenclature provides a structured way to derive these formulas.

For example, in diarsenic trioxide (As₂O₃), two arsenic atoms and three oxygen atoms are bonded together. Understanding the structure of compounds helps in predicting their behavior and properties in chemical reactions.
This knowledge is useful in fields ranging from industrial chemistry to environmental science, where understanding how compounds interact is vital.