Evaluate a neutral atom of the isotope scandium-45. Determine the number of protons in a neutral atom of scandium-45.

1. Break Down the Problem

To determine the number of protons in a neutral atom of scandium-45, we need to consider what isotopes are and what distinguishes them.

2. Relevant Concepts

An isotope of an element is defined by its number of protons and its atomic mass. The number of protons corresponds to the atomic number, which is unique to each element on the periodic table. Scandium (Sc) has an atomic number of 21.

3. Analysis and Detail

• The atomic number of scandium (Sc) is 21, which means every neutral atom of scandium, regardless of its isotope, contains 21 protons.
• The number 45 in scandium-45 refers to the atomic mass number, which is the total number of protons and neutrons in the nucleus.

4. Verify and Summarize

Since the question specifically asks for the number of protons in a neutral atom, we conclude that all neutral atoms of scandium, including scandium-45, contain 21 protons.

Final Answer

The number of protons in a neutral atom of scandium-45 is 21.