The number of neutrons in potassium will be <u>20</u>, given its atomic number is 19 and its mass number is 39.
Atomic numbers are unique to each element. The charge on the nucleus is equal to the atomic number. As a result, it also has the same numerical value as the number of electrons in the atom and the number of protons in the nucleus. The letter Z represents the atomic number.
Since each element has a unique atomic number, each element's atoms have a unique number of protons (and electrons).
The number of protons or electrons and the atomic number have the following relationships:
Atomic number = amount of protons per atom = number of electrons per neutral atom.
Additionally, each atom has a mass number, represented by the letter A. An atom's mass number is determined by how many protons and neutrons it has in total. The number of neutrons in any atom is, in other words, equal to its mass number minus its atomic number.
Mass number = number of protons + number of neutrons
or, Number of neutrons = mass number - the atomic number.
In the question, we are given that the atomic number of potassium is 19, whereas its mass number is approximately 39.
We are asked to find the number of neutrons in potassium.
Using the formula, Number of neutrons = mass number - the atomic number, we can write that:
The number of neutrons in potassium = The mass number of potassium - the atomic number of potassium,
or, The number of neutrons in potassium = 39 - 19,
or, The number of neutrons in potassium = 20.
Thus, the number of neutrons in potassium will be <u>20</u>, given its atomic number is 19 and its mass number is 39.
Learn more about the mass number and the atomic number at
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