How many protons, neutrons, and electrons are in #""_19^39 K^(+)#?

1 Answer
David Drayer
Jun 16, 2018

19 protons, 20 neutrons and 18 electrons.

Explanation:

The atomic number gives the number of protons 19

#p= 19 #

The atomic mass is the sum of the protons and neutrons

# p + n = 39# # p= 19#

put p into the equation and solve for n the neutrons.

# 19 + n = 39# Subtract 19 from both sides

# 19 -19 + n = 39 -19 #

# n = 20 #

The number of electrons equals the number of protons in a neutral atom. The positive charge equals the negative charge. The negative charge is the number of electrons. This ion has a charge of +1. So solve for the negative charge.

# -19 + 1 = -18#

The negative charge is -18 so

# e = 18#

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