On the periodic table, the element “K’ represents Potassium. Potassium has an atomic number of 19. It has an atomic mass of 39.098. The number of protons is equal to the atomic number, so Potassium has 19 protons. To find the number of neutrons in an element, subtract the atomic mass from the atomic number. (39-19). This means that the element K has 20 neutrons. Finally, to find the number of electrons, you just take the atomic number, and you have your number of electrons. Thus, Potassium has 19 electrons.
The tricks above work for any element on the Periodic Table, so feel free to use them! Here is a little way to remen then by:
A = P = E M - A = N
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I really hope this helps :)