How many neutrons are in chlorine-35?
18
17
35
Answer (2)
Identify that the mass number of chlorine-35 is 35 and the atomic number is 17.
Subtract the atomic number (number of protons) from the mass number to find the number of neutrons: 35 − 17 = 18 .
Conclude that chlorine-35 has 18 neutrons.
Explanation
Understanding the Problem We are asked to find the number of neutrons in chlorine-35, which is represented as 17 35 Cl . The mass number, which is the total number of protons and neutrons, is 35. The atomic number, which is the number of protons, is 17.
Finding the Number of Neutrons To find the number of neutrons, we subtract the number of protons (atomic number) from the mass number.
Calculation Number of neutrons = Mass number - Number of protons = 35 - 17
Final Calculation and Answer 35 - 17 = 18. Therefore, there are 18 neutrons in chlorine-35.
Examples
Understanding the number of neutrons in an atom is crucial in nuclear chemistry and physics. For example, isotopes of an element have the same number of protons but different numbers of neutrons. Chlorine-35 and chlorine-37 are isotopes of chlorine. Chlorine-35 has 17 protons and 18 neutrons, while chlorine-37 has 17 protons and 20 neutrons. These different isotopes have slightly different masses, which affects their behavior in chemical reactions and nuclear processes. In nuclear medicine, radioactive isotopes are used for imaging and treatment, and the number of neutrons affects the stability and decay mode of the isotope.
Chlorine-35 has a mass number of 35 and an atomic number of 17. By subtracting the atomic number from the mass number, we find that chlorine-35 contains 18 neutrons. Thus, the answer is 18 .
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