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An atom of a certain element has 19 protons, 19 electrons, and a mass number of 39. This element is very reactive. How many neutrons are in this atom?

Answer :

JACOB193GO

Answer:

There would be [tex]20[/tex] neutrons in that atom.

Explanation:

The mass number of an atom is the sum of:

  • the number of neutrons in this atom, and
  • the number of protons in this atom.

Electrons do not contribute to the mass number of an atom.

From the question:

  • Mass number of this atom: [tex]39[/tex].
  • Number of protons in this atom: [tex]19[/tex].

[tex](\text{Mass Number}) = (\text{Number of protons}) + (\text{Number of neutrons})[/tex].

In this atom:

[tex]39 = 19 + (\text{Number of neutrons})[/tex].

Hence, the number of neutrons would be [tex]39 - 19 = 20[/tex].

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