Question

The atomic number of an element is best determined by which of the following? Choose one:

A. the number of protons in its nucleus
B. the number of neutrons in its nucleus
C. the number of electrons it has
D. the number of protons and electrons it has
E. the number of protons and neutrons it has

Answer 1

The atomic number of an element is defined by the number of protons in its nucleus, and it is also equal to the number of electrons in a neutral atom of that element.

Step-by-step explanation:

The atomic number of an element is best determined by the number of protons in its nucleus. This is a fundamental characteristic that defines an element and distinguishes it from others. Every atom of an element has the same number of protons in its nucleus, which reflects its atomic number. For example, all carbon atoms have 6 protons. While neutrons do not affect the atomic number, they, along with protons, contribute to the mass number. Therefore, for an electrically neutral atom, the atomic number also indicates the number of electrons. All these properties are crucial for understanding an element's identity and behavior.