Part of Speech

Noun

Pronunciation

/əˈtɒmɪk weɪt/ (uh-TOM-ik WAYT)

Definitions

• 1. The average mass of the atoms of an element, measured in atomic mass units, taking into account the natural isotopic distribution of the element.
• 2. The weighted average of the atomic masses of all the naturally occurring isotopes of an element, relative to the mass of an atom of carbon-12, which is defined as 12 atomic mass units.
• 3. A measure of the mass of an element’s atoms based on a scale where carbon-12 is assigned a mass of exactly 12 atomic mass units.

Usage Examples

• The atomic weight of oxygen is approximately 16, meaning that oxygen atoms are roughly 16 times heavier than the carbon-12 isotope.
• To calculate the atomic weight of an element, one must consider the relative abundances of its isotopes.
• The atomic weight of an element is important in determining the stoichiometry of chemical reactions and molecular masses.

Etymology

The term "atomic weight" derives from the combination of "atomic," referring to atoms or atoms of an element, and "weight," referring to mass. The term "atomic" comes from the Greek word "atomos," meaning indivisible, as atoms were once thought to be the smallest indivisible units of matter. The concept of atomic weight emerged in the 19th century as scientists began to study the relative masses of atoms and isotopes.

Synonyms

• Atomic mass
• Atomic number (though this refers to a different concept)
• Relative atomic mass
• Molar mass (related, but refers to the mass of one mole of substance)

Antonyms

• Massless
• Zero mass

Translations

Regional Pronunciation Variations

Pronunciation may vary depending on the accent of the speaker. For example, in British English, "atomic weight" may sound slightly more clipped and with emphasis on the first syllable of "atomic," while American English may have a softer 't' sound. In other languages like Spanish, French, and Russian, the term follows the phonetic rules of each language, but the concept remains the same.

Historical Usage

The concept of atomic weight was first proposed in the early 19th century when chemists, including John Dalton, began to study the relative masses of elements. Dalton's atomic theory, developed in the 1800s, posited that each element is made up of atoms of a single, unique type, and that the relative weights of atoms could be determined by comparing them. Over time, the discovery of isotopes led to a refinement of the concept, transitioning from atomic weight to the more precise concept of atomic mass.

Cultural Nuances

The concept of atomic weight, while a cornerstone in chemistry, may not be familiar to the general public. However, it has cultural significance in scientific communities, especially in the fields of nuclear chemistry and physics. The term is often associated with the study of atomic and subatomic particles, and may be discussed in relation to nuclear energy, environmental science, and other scientific disciplines. Atomic weight has also been referenced in pop culture, especially in fictional works that explore atomic theory and nuclear science.

More Information

Atomic weight is an essential concept in understanding atomic structure and chemistry. It plays a crucial role in calculating the stoichiometry of chemical reactions and is important in molecular biology, pharmacology, and material science. While atomic weight provides an average of an element's isotopes, the concept of atomic mass is now more commonly used in modern scientific research due to its precision and relevance to atomic theory. Advances in spectroscopy and mass spectrometry have made it easier to determine atomic weights with high accuracy. Despite this, the term "atomic weight" remains in widespread use, particularly in educational contexts and in the periodic table of elements.