What is the atomic mass of element X if it is equivalent to the total mass of 7 hydrogen atoms

To determine the atomic mass of element X, which is equivalent to the total mass of 7 hydrogen atoms, we need to understand the atomic mass of a hydrogen atom. A hydrogen atom has an atomic mass of approximately $1.00784$ atomic mass units (amu).

Calculation

The total mass of 7 hydrogen atoms can be calculated as follows:

Let's perform the multiplication:

Thus, the atomic mass of element X is:

Therefore, the atomic mass of element X is 7.05488 amu.

Atomic Mass Unit (amu) Concept

The atomic mass unit (amu) is a standard unit of mass that quantifies mass on an atomic or molecular scale. It is particularly useful for comparing the masses of different atoms and molecules.

Definition

The atomic mass unit is defined as one twelfth of the mass of an unbound neutral carbon-12 atom in its ground state. Mathematically, this is expressed as:

Where $m (\text{C-12})$ is the mass of a carbon-12 atom.

Numerical Value

The value of 1 atomic mass unit in kilograms is:

Application

Atomic mass units are primarily used in chemistry and physics to express:

• Atomic masses: The mass of a single atom of an element, which is often close to an integer and called the atomic weight.
• Molecular masses: The mass of a single molecule, calculated as the sum of its constituent atoms' masses.

Relationship with Avogadro's Number

The concept of the atomic mass unit is tightly related to Avogadro's number ($N_A$), which is defined as the number of atoms in 12 grams of carbon-12:

Thus, the molar mass of a substance (in grams per mole) is numerically equal to the atomic or molecular mass (in amu).

Importance

Using atomic mass units simplifies the expression and comparison of atomic and molecular masses. For example:

• An oxygen atom has an atomic mass of approximately 16 amu.
• A water molecule (H$_2$O) has a molecular mass of approximately 18 amu.

In summary, the atomic mass unit provides a convenient and standardized way to express and compare small masses at the atomic scale.

Understanding Multiplication of Atomic Mass

Atomic mass, often listed on the periodic table, refers to the average mass of an element’s atoms, typically measured in atomic mass units (amu). This value is crucial when performing chemical calculations, including the multiplication of atomic masses.

Concept of Atomic Mass

The atomic mass of an element is essentially a weighted average that takes into account the various isotopes of that element and their relative abundances.

Let’s say we have:

Multiplication for Molecule Mass Calculation

When we want to find the mass of a molecule, we essentially multiply the atomic masses of the constituent atoms by their respective quantities in the molecule. For example, for a water molecule ($\text{H}_2\text{O}$):

Given:

The total mass of a water molecule would be:

General Formula

For a generic molecule $\text{A}_m \text{B}_n$:

Practical Applications

• Stoichiometry: Helps in determining the ratios of reactants and products in chemical reactions.
• Molecular Weight Calculation: Essential for identifying substances and their proportions in compounds.
• Pharmaceuticals: Useful in drug formulation and determining active ingredient concentrations.

Multiplying atomic masses is a foundational step for numerous chemical computations, making it an essential concept for understanding molecular compositions and reactions.