Question

Write the formula for each of the following substances, listing the elements in the order given. a. List the phosphorus atom first. b. a molecule containing two boron atoms and six hydrogen atoms c. a compound containing one calcium atom for every two chlorine atoms d. List the carbon atom first. e. a compound containing two iron atoms for every three oxygen atoms f. a molecule containing three hydrogen atoms, one phosphorus atom, and four oxygen atoms

Short answer

a. \(P\) b. \(B_2H_6\) c. \(CaCl_2\) d. \(C\) e. \(Fe_2O_3\) f. \(H_3PO_4\)

Step-by-step solution

a. Phosphorus atom

Since we are asked to list the phosphorus atom first, we'll use the chemical symbol "P" for phosphorus. Since there is only one phosphorus atom, there is no need for a subscript. The formula for the substance is simply: \(P\)

b. Two boron atoms and six hydrogen atoms

We are given that the molecule contains two boron atoms and six hydrogen atoms. We'll use the chemical symbols "B" for boron and "H" for hydrogen and add appropriate subscripts. The formula for the substance is: \(B_2H_6\)

c. One calcium atom and two chlorine atoms

We are given that the compound contains one calcium atom for every two chlorine atoms. We'll use the chemical symbols "Ca" for calcium and "Cl" for chlorine and add appropriate subscripts. The formula for the substance is: \(CaCl_2\)

d. Carbon atom

Since we are asked to list the carbon atom first, we'll use the chemical symbol "C" for carbon. Since there is only one carbon atom, there is no need for a subscript. The formula for the substance is simply: \(C\)

e. Two iron atoms and three oxygen atoms

We are given that the compound contains two iron atoms for every three oxygen atoms. We'll use the chemical symbols "Fe" for iron and "O" for oxygen and add appropriate subscripts. The formula for the substance is: \(Fe_2O_3\)

f. Three hydrogen atoms, one phosphorus atom, and four oxygen atoms

We are given that the molecule contains three hydrogen atoms, one phosphorus atom, and four oxygen atoms. We'll use the chemical symbols "H" for hydrogen, "P" for phosphorus, and "O" for oxygen and add appropriate subscripts. The formula for the substance is: \(H_3PO_4\)

Key concepts

Molecular Composition

Molecular composition refers to the specific arrangement and number of atoms that make up a molecule. Each molecule has a distinct formula that represents its composition, indicating the types and counts of atoms present. For example, water has a molecular formula of \( H_2O \), showing it contains two hydrogen atoms and one oxygen atom.
Understanding molecular composition is crucial for studying chemical properties and reactions. The composition gives insight into how molecules interact, react, and transform under different conditions. By knowing the number and type of atoms, chemists can predict reactivity and stability of molecules, which is vital in fields such as pharmacology, materials science, and environmental science.

Chemical Symbols

Chemical symbols are shorthand notations representing elements derived from either their English names or Latin roots. Each element in the periodic table is assigned a unique chemical symbol, usually consisting of one or two letters.
For instance:

• The symbol for carbon is \( C \).
• The symbol for iron is \( Fe \), from the Latin word 'ferrum'.
• The symbol for oxygen is \( O \).

These symbols form the building blocks in writing chemical formulas, providing a universal language for scientists worldwide.
Using symbols allows for concise and clear communication about chemical compositions and reactions.

Compound Formation

When elements combine, they form compounds, which are substances made up of two or more elements in specific ratios. Understanding how compounds form is key to grasping chemistry.
The formation of compounds involves:

• Identifying the constituent elements and their chemical symbols.
• Determining the ratio of each element based on bonding needs and reactivity.
• Writing a chemical formula that represents this arrangement, denoting the quantity of each atom by subscripts.

For example, calcium chloride is formed from one calcium atom and two chlorine atoms, resulting in the formula \( CaCl_2 \).
Knowledge of compound formation helps in predicting how different substances interact, assisting in creating new materials and understanding biochemical processes.

Chemical Subscripts

Chemical subscripts provide information on the number of atoms of each element present in a molecule. Positioned immediately after the chemical symbol, they indicate how many atoms of the element are in the compound.
For example:

• In \( H_2O \), the subscript 2 shows there are two hydrogen atoms in each water molecule.
• In \( CO_2 \), the subscript 2 shows two oxygen atoms combined with one carbon atom.

If there is only one atom of a particular element, no subscript is written, as seen in \( CH_4 \) for methane.
Subscripts are essential for accurately representing chemical formulas, enabling precise communication about a substance's molecular structure.