explain atoms are electrically neutral
Answers
By definition, an atom is electrically neutral (i.e. has the same number of protons as it does electrons, plus some number of neutrons depending on the isotope). If a species were charged, it is referred to as an ion (cation for positively charged and anion for negatively charged species), also by definition.
But this is probably not a very satisfying answer. (I personally find answers based on definitions pretty bland.) Perhaps an interesting follow up question is...
Is the universe electrically neutral?
For many instances in science, we deal with systems where charge neutrality is very important.
Perhaps a common example you might be familiar with is table salt, NaCl. Before forming salt, both sodium (Na) and chlorine (Cl) are electrically neutral atoms. Then chlorine nabs an electron from a sodium because it is more energetically favorable for it to have an additional electron. You then have a Na+ cation and Cl- anion that combine into NaCl due to electrostatic attraction. Overall, NaCl is a neutral system (table salt doesn't shock you when you eat it... hopefully).
This property of electrical neutrality is also very important in the work that I do every day. I do computational research on crystals like NaCl where we calculate energies of a variety of sorts to understand the material. Part of calculating the total energy of a system for a crystal like NaCl involves the energy contribution that arises from Coulombic forces between every combination of Na+ and Cl- anion. This would mean figuring this out for something like 1023 ions (which is a lot). We do something a little more clever. NaCl is a crystal, which means it has a periodic (i.e. repeating) structure, so we only need to consider a unit cell, or small portion that can reproduce the entire crystal structure by translating it. But this means what we model is infinitely large materials. This is okay for bulk materials, since surface effects are small.
What is more worrying are those long range Coulombic forces. If we're not careful, we could end up with infinite energy! And that would be no good. This can be solved with a clever way of adding Coulombic forces (called Ewald summation) and a charge neutral unit cell.
Hope this helps!
1) An atom is made up of a nucleus and an extra-nuclear part. Protons and neutrons are present in the nucleus.
2) The nucleus is positively charged. The extra nuclear part is made up of negatively charged electrons.
3) Protons are positively charged, electrons are negatively charged and neutrons are without any change.
4) The magnitude of their charges is Same when they are equal in number.
5) Hence, the negative charge on all the extra, nuclear electrons together balances the positive charge on the nucleus.
6) Therefore, an atom is electrically neutral though it contains charged particles.