Question #90268

1 Answer
Apr 19, 2017

Because the positive and negative charges cancel out, and you are left with only neutral charges.

Explanation:

An atom has three different subatomic particles:

  • Proton - positive charge
  • Neutron - neutral charge
  • Electron - negative charge

The protons and neutrons live in the nucleus of an atom (its center), and contain most of the atom's mass. The electrons 'orbit' the nucleus in shells, or energy levels.

In a neutral atom, the number of protons = the number of electrons.

Extra:

You can't change the number of protons in the atom of and element without changing that element. If you change the number of neutrons, you have something called an isotope. When you change the number of electrons you have an ion. This positive/negative relationship is seen in the ion charges of atoms.

For example, Na+ is a neutral Na atom with one electron taken away. Normally, a neutral Na atom has 11 protons and 11 electrons.

When it loses one electron, it becomes Na+. Why? Well, you started with 11 protons and 11 electrons. Take one electron away, and you have 11 protons, which have a positive charge, and 10 electrons, which have a negative charge.

Since there is one more positive charge than negative charge (i.e. the sum of positive 11 and negative 10), the charge of Na+ is positive 1, or +.