(a) What is the mass in u of a carbon-12 atom?

Verified step by step guidance

1. Understand that the atomic mass unit (u) is defined based on the carbon-12 isotope. By definition, one carbon-12 atom has a mass of exactly 12 atomic mass units (u).
2. Recall that the atomic mass unit is a standard unit of mass that quantifies mass on an atomic or molecular scale (1 u is approximately equal to 1.66053906660 x 10^-27 kg).
3. Recognize that the mass of a carbon-12 atom is used as a reference point for the atomic mass unit, meaning it is exactly 12 u by definition.
4. Consider that this definition is crucial for understanding atomic masses of other elements, as they are measured relative to the carbon-12 standard.
5. Conclude that the mass of a carbon-12 atom is exactly 12 u, which is a fundamental concept in chemistry for determining the relative atomic masses of other elements.

Key Concepts

Atomic Mass Unit (u)

The atomic mass unit (u) is a standard unit of mass used to express atomic and molecular weights. It is defined as one twelfth of the mass of a carbon-12 atom, which is approximately 1.66 x 10^-27 kg. This unit allows chemists to compare the mass of different atoms and molecules on a relative scale.

Carbon-12 Isotope

Carbon-12 is one of the isotopes of carbon, consisting of 6 protons and 6 neutrons in its nucleus. It is the most abundant carbon isotope, making up about 98.9% of natural carbon. The mass of a carbon-12 atom is defined as exactly 12 u, serving as a reference point for measuring the masses of other isotopes and elements.

Mass Spectrometry

Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of ions. It helps in determining the composition of a sample by identifying the masses of its constituent atoms or molecules. Understanding mass spectrometry is essential for interpreting atomic masses and isotopic distributions, which are relevant when discussing the mass of carbon-12.