Problem 40 - Introductory Chemistry Atoms First

Question

The smallest possible piece of the compound hydrogen peroxide contains two hydrogen atoms and two oxygen atoms. Write the chemical formula for hydrogen peroxide, with hydrogen first.

Step-by-Step Solution

Answer

The chemical formula for hydrogen peroxide is \(H_2O_2\).

Step 1: Understand the elements in question

Hydrogen is represented by the chemical symbol "H" and it has a valency of 1 (it can form one bond), whereas oxygen has the chemical symbol "O" and a valency of 2 (it can form two bonds).

Step 2: Combine the elements

To form a hydrogen peroxide molecule, we will need: - Two hydrogen atoms (each having a valency of 1) which will form one bond each. - Two oxygen atoms (each having a valency of 2) which will form two bonds each.

Step 3: Write the chemical formula

Now we can write the chemical formula for hydrogen peroxide with hydrogen first. We have two hydrogen atoms and two oxygen atoms. In a chemical formula, when more than one atom of an element is present, we write the number of atoms as a subscript. In this case, the chemical formula for hydrogen peroxide is: \(H_2O_2\)

Key Concepts

Chemical Symbols

At the heart of chemistry lie chemical symbols, which are simply abbreviated forms of elements' names, primarily derived from their Latin names. For example, hydrogen, a colorless, odorless gas and the most abundant element in the universe, is represented by the symbol 'H'. Meanwhile, oxygen, essential for the survival of aerobic organisms, bears the symbol 'O'. These symbols, standardized by the International Union of Pure and Applied Chemistry (IUPAC), serve as the universal language of chemistry, allowing scientists around the world to communicate with clarity and precision.

Understanding chemical symbols is fundamental when writing chemical formulas since every compound is represented by the symbols of the elements it contains. For instance, water, consisting of hydrogen and oxygen, is depicted as H2O. In the chemical formula for hydrogen peroxide, the symbols 'H' and 'O' denote the presence of hydrogen and oxygen atoms, respectively.

Valency of Elements

Valency is the term used to describe the combining power of an element, essentially indicating how many bonds a particular atom of an element can form with other atoms. It stems from an element's ability to donate, accept, or share electrons with other atoms to achieve a stable electronic configuration, often resembling that of the nearest noble gas.

For instance, hydrogen atoms, with one electron, have a valency of one, denoting they can form one bond to attain a stable structure, similar to helium. Oxygen atoms, with six electrons in their outer shell, have a valency of two, enabling them to form two bonds, seeking to fill their shell with eight electrons for stability, akin to neon. In the molecular structure of hydrogen peroxide, this concept helps explain why two hydrogen atoms bond with two oxygen atoms to fulfill the valency requirements, leading to the formation and stability of the compound.

Writing Chemical Formulas

Writing chemical formulas is akin to constructing a molecule's blueprint; it involves a systematic representation of the types and numbers of atoms present in a molecule. When writing a chemical formula, one first identifies the elements involved using their chemical symbols, as we've explored with both hydrogen and oxygen. Afterward, reflecting on the valency of elements, we figure out the necessary quantity of each atom to establish a stable molecule with fully satisfied valencies.

For hydrogen peroxide, we write hydrogen first (as instructed in the exercise), followed by oxygen. Since the molecule comprises two hydrogen atoms and two oxygen atoms, we apply subscripts to represent these quantities, resulting in the chemical formula \(H_2O_2\). The subscript is a fundamental notation that tells us the exact number of atoms of each element in the compound, providing a clear picture of its molecular composition. Without these details, it would be impossible to grasp the compound's precise nature and properties.