# When we say an atom has a charge of +1 or -2, what does that quantity refer to? Is it a measurable force? An energy quantity?

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I understand it means that it has more protons or electrons but what does ‘charge’ actually mean? I feel like I know it but I can’t explain it.

In: Chemistry

As far as I remember, if an atom has a charge of +1, that means it has a single electron less situated in it‘s most outer energy level.

Since we already measured the charge of an electron, it should be easy for you to look it up and quantify it accordingly to your relevant charge.

Yeah, the charge can be seen as energy, or charge, and is typically written in eV.

Also, the type of your question makes me think you are mostly talking about positively charged ions and negativity charged ones, in order to have a redox-reaction for example.

In that case it has nothing to do with changing proton quantities-it’s all about electrons.

-1 => 1 times negatively charged, aka +1 electron

+2 => 2 times positively charged, aka -2 electrons

It is the fundamental electric charge, the charge possessed by the electron (-1e) and the proton (+1e). Likewise, the positron, antimatter electron, has a +1e charge, and the anti-proton (aka “negatron,” though that sounds like a Transformer) has a -1e chage. We just usually leave the “e” out because it’s considered unnecessary, since it’s always the same electron charge everywhere.

An ion has “+1” charge if it is missing one electron relative to how many protons it has. An ion has a “-2” charge if it has two excess electrons relative to how many protons it has.

As for what charge *in general* is? It’s how much electric-ness there is in a given quantity of space. Just like how mass is simply a *property* that some objects have and others don’t (e.g. photons have no mass, only momentum), some objects have electric charge and others don’t.

Atoms have valence shells, orbitals that layer themselves over the proton and neutron core that do (or don’t) contain electrons. An atom with the exact same number of protons in the core as electrons distributed among its “shells” has a charge of 0.

These “shells” will be there regardless of whether or not there’s enough protons to justify them. So, atoms can get additional electrons filling these outer shells _beyond_ the number of protons, giving the whole atom a -1 or -2 or so on charge. Similarly, these shells can be empty, more so than the proton count would likely indicate, giving the atom a +1 or +2 or so on charge.

Trends in this and some of the reasoning behind why this can be stable/unstable and so on is a bit more of an advanced area, but an important note is that these shells essentially form layers, that are the rows of the periodic table. A layer with only one or two electrons (or missing only one or two) tends to favor either completely filling its shell (even if it’s unbalanced), or getting rid of the fringe electrons forming a new layer. These two opposite ends pair together well, and make up a lot of salts. E.g., Na+CL-, which separate in solution and remain fairly stable, but can also form a solid without ever forming a true bond.

That is the charge in terms of elementary charge.

The elementary charge is 1.6×10^-19 C, C is the unit for Coulombs.

1 A = 1 C/s, you may be familiar with amps being the measure of electrical current.

The charge of an electron is -1.6×10^-19 C or -1 *e*

The charge of a proton is 1.6×10^-19 C or 1 *e*

When an atom is missing on electron, the atom has a net charge of +1 *e*

When the atom has 2 extra electrons, the atom has a net charge of -2 *e*

Consider how “mass” works.

Mass isn’t a “force”, but two masses absolutely have gravitational forces that pull them together based on “how massive” each one is and “how far away” the two masses are from one another.

Consider that “charge” is very similar.

Charge isn’t a “force”, but two charges absolutely have electrostatic forces that pull them together based on “how charged” each one is and “how far away” the two charges are from one another. (Electrostatic forces are also interesting in that they will be repulsive or attractive depending upon whether the charges match or mismatch, respectively.)

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As for “What does the quantity refer to?” its *units* are in terms of electron-charges (-1) or proton-charges (+1); they have the same unit value and differ only in +/-.

An atom with +1 charge means that, if you add up all of the +1s from it’s protons, and all the -1s from it’s electrons, there is still +1 left over. (e.g. 5x +1s and 4x -1s leaves +1 overall, but 5x +1s and 2x -1s would leave +3 overall.)