What uniquely defines an element in the periodic table?

What uniquely defines an element in the periodic table?

• A. Number of electrons
• B. Number of neutrons
• C. Number of protons in the nucleus
• D. Atomic mass

Answer: (C)

An element in the periodic table is uniquely defined by the number of protons in its nucleus, commonly referred to as the atomic number. This number is fundamental because it determines the identity of the element; for example, hydrogen has one proton, while carbon has six. The number of protons also dictates the arrangement of electrons around the nucleus, affecting how the element interacts chemically with others. While electrons and neutrons play essential roles in determining the overall properties of an atom, they do not uniquely identify an element. Different elements can have the same number of electrons in certain ionization states. Additionally, the number of neutrons can vary among atoms of the same element, leading to different isotopes, but these variations do not change the elemental identity. Atomic mass, which is a weighted average of the masses of an element's isotopes, varies depending on the composition of neutrons and protons as well. However, it is the number of protons that provides the established definition of an element in chemistry.

An element in the periodic table is uniquely defined by the number of protons in its nucleus, commonly referred to as the atomic number. This number is fundamental because it determines the identity of the element; for example, hydrogen has one proton, while carbon has six. The number of protons also dictates the arrangement of electrons around the nucleus, affecting how the element interacts chemically with others.

While electrons and neutrons play essential roles in determining the overall properties of an atom, they do not uniquely identify an element. Different elements can have the same number of electrons in certain ionization states. Additionally, the number of neutrons can vary among atoms of the same element, leading to different isotopes, but these variations do not change the elemental identity. Atomic mass, which is a weighted average of the masses of an element's isotopes, varies depending on the composition of neutrons and protons as well. However, it is the number of protons that provides the established definition of an element in chemistry.