Determine the number of protons, electrons and neutrons in chlorine atoms with a relative atomic mass of 35.

CL – in the periodic system of Mendeleev has number 17. The number of protons (p), the number of electrons (e) of a chemical element are equal to the ordinal number. Protons carry a positive charge, so they are written with a plus sign, electrons carry a negative charge, so they are written with a minus sign. neutrons (n) are found by subtracting the serial number from the mass of the element, i.e. the number of protons.
Answer: CL has p = +17, e = -17, n = 35 -17 = 18.