To determine the number of protons, neutrons, and electrons in a potassium atom with an atomic number of 19 and an atomic mass number of 39, follow these steps:
1. Number of Protons
The atomic number of an element is equal to the number of protons in its nucleus. For potassium, the atomic number is 19. Therefore, the number of protons in a potassium atom is:
Number of Protons = Atomic Number = 19
2. Number of Electrons
In a neutral atom, the number of electrons is equal to the number of protons. Since the potassium atom is neutral, the number of electrons is also 19.
Number of Electrons = Number of Protons = 19
3. Number of Neutrons
The atomic mass number is the sum of the number of protons and neutrons in the nucleus. To find the number of neutrons, subtract the atomic number from the atomic mass number:
Number of Neutrons = Atomic Mass Number – Atomic Number
Number of Neutrons = 39 – 19 = 20
So, a neutral potassium atom with an atomic number of 19 and an atomic mass number of 39 has:
- 19 Protons
- 19 Electrons
- 20 Neutrons