The unified atomic mass unit (u) 1/12 the mass of a neutral atom of: (a) 1^H (b) 12^C (c) 14^C (d) 16^O

Verified step by step guidance

1. Understand that the unified atomic mass unit (u) is defined as 1/12 the mass of a neutral atom of a specific isotope.
2. Identify the isotope used for this definition, which is the carbon-12 isotope.
3. Recognize that the symbol for carbon is 'C' and the isotope number is written as a superscript before the element symbol.
4. Match the isotope number and element symbol to the options provided in the problem.
5. Conclude that the correct answer is the isotope with the symbol 12^C, which corresponds to option (b).

Key Concepts

Atomic Mass Unit (u)

The atomic mass unit (u) is a standard unit of mass that quantifies mass on an atomic or molecular scale. 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 express atomic and molecular weights in a more manageable form, facilitating comparisons between different elements and compounds.

Isotopes

Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. For example, carbon-12 (12^C) has six protons and six neutrons, while carbon-14 (14^C) has six protons and eight neutrons. Understanding isotopes is crucial for interpreting atomic mass and the stability of elements.

Neutral Atoms

A neutral atom is one that has an equal number of protons and electrons, resulting in no overall electric charge. This balance is essential for the stability of the atom and influences its chemical behavior. In the context of atomic mass, the mass of a neutral atom is used to define the atomic mass unit, as it reflects the total mass of protons and neutrons in the nucleus.