Question

Identify the elements represented in each of the following chemical formulas and tell the number of atoms of each element: (a) \(\mathrm{NH}_{3}\) (ammonia) (b) \(\mathrm{NaHCO}_{3}\) (sodium hydrogen carbonate) (c) \(\mathrm{C}_{8} \mathrm{H}_{18}\) (octane, a component of gasoline) (d) \(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}(\) vitamin \(\mathrm{C})\)

Short answer

(a) N:1, H:3 (b) Na:1, H:1, C:1, O:3 (c) C:8, H:18 (d) C:6, H:8, O:6

Step-by-step solution

Break Down Formula for Ammonia - NH3

Identify each element in the formula \( \mathrm{NH}_{3} \). There are two elements present: nitrogen (\( \mathrm{N} \)) and hydrogen (\( \mathrm{H} \)). Next, count the number of atoms of each element. In this case, there is 1 nitrogen atom and 3 hydrogen atoms.

Analyze Formula for Sodium Hydrogen Carbonate - NaHCO3

In the chemical formula \( \mathrm{NaHCO}_{3} \), identify the elements: sodium (\( \mathrm{Na} \)), hydrogen (\( \mathrm{H} \)), carbon (\( \mathrm{C} \)), and oxygen (\( \mathrm{O} \)). Count the atoms: 1 sodium atom, 1 hydrogen atom, 1 carbon atom, and 3 oxygen atoms are present.

Examine Formula for Octane - C8H18

For \( \mathrm{C}_{8} \mathrm{H}_{18} \), identify the elements: carbon (\( \mathrm{C} \)) and hydrogen (\( \mathrm{H} \)). Count the atoms: there are 8 carbon atoms and 18 hydrogen atoms.

Inspect Formula for Vitamin C - C6H8O6

In \( \mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6} \), identify the elements: carbon (\( \mathrm{C} \)), hydrogen (\( \mathrm{H} \)), and oxygen (\( \mathrm{O} \)). Count the atoms: there are 6 carbon atoms, 8 hydrogen atoms, and 6 oxygen atoms.

Key concepts

Element Identification

Chemistry relies on understanding the elements that make up various compounds, as this forms the basis for predicting chemical reactions and behavior. **Element identification** is about recognizing the symbols found in chemical formulas. These symbols are shorthand notations representing chemical elements on the periodic table. For example:

• In the formula \( \mathrm{NH}_{3} \), \( \mathrm{N} \) stands for nitrogen and \( \mathrm{H} \) stands for hydrogen.
• In \( \mathrm{NaHCO}_{3} \), \( \mathrm{Na} \) is sodium, \( \mathrm{H} \) is hydrogen, \( \mathrm{C} \) is carbon, and \( \mathrm{O} \) is oxygen.
• \( \mathrm{C}_{8} \mathrm{H}_{18} \) consists of carbon (\( \mathrm{C} \)) and hydrogen (\( \mathrm{H} \)).
• \( \mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6} \) includes carbon (\( \mathrm{C} \)), hydrogen (\( \mathrm{H} \)), and oxygen (\( \mathrm{O} \)).

By understanding these symbols and what they represent, one can quickly deduce what elements are in a compound, and set the stage for further analysis of the compound's structure and behavior.

Atomic Count

Determining the **atomic count** of elements in a chemical formula is essential. It involves counting how many atoms of each type are present within a compound. Knowing this helps in calculating molecular weights and understanding a compound's balance. Let's break down a few examples:

• For \( \mathrm{NH}_{3} \), you have 1 nitrogen atom and 3 hydrogen atoms.
• In \( \mathrm{NaHCO}_{3} \), there is 1 sodium atom, 1 hydrogen atom, 1 carbon atom, and 3 oxygen atoms.
• \( \mathrm{C}_{8} \mathrm{H}_{18} \) means 8 carbon atoms and 18 hydrogen atoms make up the molecule.
• \( \mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6} \) consists of 6 carbon atoms, 8 hydrogen atoms, and 6 oxygen atoms.

Counting atoms precisely is crucial in stoichiometry, which involves calculating reactants and products in chemical reactions.

Molecular Composition

The **molecular composition** of a chemical compound describes the specific arrangement and number of atoms within a molecule. It dictates the properties and reactions of the compound. Let’s explore some examples:

• \( \mathrm{NH}_{3} \), also known as ammonia, has nitrogen centrally bonded to three hydrogens, forming a trigonal pyramidal shape.
• \( \mathrm{NaHCO}_{3} \) is sodium hydrogen carbonate, where sodium forms ionic bonds with a bicarbonate group (\( \mathrm{HCO}_{3}^- \)) that influences its use in baking and medication.
• Octane (\( \mathrm{C}_{8} \mathrm{H}_{18} \)) is primarily used as a fuel, and its long carbon chain provides high-energy bonds when combusted.
• \( \mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6} \), commonly known as vitamin C, has a hexose structure, pivotal in antioxidation processes in the body.

Understanding molecular composition helps chemists predict how a compound behaves in different environments and its possible applications.