# If something is electrically charged, it's.. ?

Just trying to learn some basic physics, but am struggling to navigate my way around wikipedia’s circular use of terms.

Let’s say we have an iron rod. Each atom within the rod has 26 electrons. Is the following correct?:

*A positively charged iron rod has an “excess” of electrons. It has 26 electrons per atom, plus some electrons that are “free flowing” around the rod, not belonging to any particular atom.

A negatively charged iron rod has a “deficiency” of electrons, with some atoms having to “share” electrons to make up for the deficiency.*

Is the above correct?

Please keep any responses to completely layman’s terms.

Thank you.

no. in fact, completely opposite.

a rod is made up of atoms. each atom, depending on the element, has a set number of protons in the nucleus. protons are positive. around the atom are electrons. electrons are negative. electrons flow and protons don’t. so, when electrons flow off the rod, there is more positive charge than negative charge, rendering the rod “positive”. when electrons flow onto the rod, there are more electrons than protons - making it “negative”. that’s about as lay as it gets.

It can be confusing, because the flow of electricity (positive charge) is the opposite of the flow of electrons (which are the only things actually moving).

However, it’s too late to do anything about that.

Thank you for the response.

So something is positively charged if there is an imbalance between the number of protons and electrons, in favour of the protons?

If yes, do atoms on a positively charged “thing” have to “share” electrons to make up for the deficiency?

Try to realize, by the definition we currently use*, all electrons in a metal exist as a “sea” of electrons – all atoms are sharing all electrons, whether they’re balanced or not.

*Note: this is a model we use to understand these sort of concepts, I do not have a citation to first hand observation of atoms, protons, or electrons.

They often will, but they don’t have to. They often simply exist in an ionic form.

Certainly not all the electrons in the metal are free flowing. The electrons in the conduction band are free flowing. The non-valence electrons are not free flowing. At what point in the electronic configuration the electrons become free flowing, I don’t know. Possibly all valence electrons are free flowing.

Yes.

Something is charged if there is an imbalance between the number of protons and electrons. If it’s an atom or molecule, it’s called an ion.

If there are more protons than electrons, the item is positively charged. If it’s an atom or molecule, it’s a cation.

If there are less protons than electrons, the item is negatively charged. If it’s an atom or molecule, it’s an anion. If you’re familiar with word roots this is mnemotechnic, as “an” means “negative.”

What electrons would they share? There’s no extras! Depending on the specific “thing,” the charge may be spread out among several atoms (from “two” in a specific arrangement in organic chemistry, to “every atom in the chunk” in a chunk of metal); this applies whether the charge is positive (missing electrons/extra protons) or negative (extra electrons/missing protons).

One of the most common mechanisms in organic chemistry is having either a cation attach itself to a high-electron-density part of another molecule, or an anion attach itself to a low-electron-density part of a different molecule. That’s similar to what you’re thinking of, but in a much smaller scale.

One of the most common types of chemical bonds is the ionic bond, where ions with positive and negative charges stay close to each other so the global charge is zero, but each ion stays charged and doesn’t either hand over the extra electrons or grab some"body"-else’s. This kind of bond happens for example in table salt, NaCl, where the Na is Na[sup]+[/sup] and the Cl is Cl[sup]-[/sup]. That’s a molecule with a very simple formula; bicarbonate, NaHCO[sub]3[/sub] is more complex and its two ions are Na[sup]+[/sup] and HCO[sub]3[/sub][sup]-[/sup].

It should be noted that for charged objects in our everyday experience, the imbalance in protons and electrons is absolutely minuscule compared to the total number of protons and electrons. A coulomb of charge, which for most practical purposes is an absolutely huge amount of charge, is about 10[sup]19[/sup] electrons, while an object with mass of a few kilograms has about 10[sup]27[/sup] electrons in it. So if you took such an object, and charged it up to a full coulomb (which, as mentioned, is far larger than you’ll ordinarily see), the electrons it’s gained or lost are about ten parts per billion.

Of course even in cases where the charge is nominally located on one atom it is in reality quite spread out. The best example is in the order of stability for carbon cations. The t-butyl cation actually spreads it’s charge among the other atoms even though the way we draw these species does not represent this. In the case of organic molecules, it’s called hypervalency, but actuallymost atoms will spread their charge. If you were to calculate the partial charge (Mulliken Charge for example) for the iron in ferrocene, I’m sure that you would find that the charge is pretty close to zero even though we represent it as iron(II).

Thank you to everyone who responded.

Two more points of possible interest.

Generally when you move charge around you are actually moving the electrons, per the first two answers and beyond. It is at the surface of the object that the surplus or deficit lives. You will recall that two charges of the same sign repel each other. This means that all the excess charge spreads itself over the surface and especially tends to crowd toward the points that stick out the furthest, in an attempt to get away from itself.

And, at least for very small objects (dust particles), if they are charged enough, they will explode as the charge tries to get away from itself.

My Physics teacher in high school mentioned this and said “…so, if you remove 10 [sup]15[/sup] electrons from an object, it’s not going to shrivel up.”

It is also important to understand that “the flow of electricity (conventional current)” is not the same as the flow of electrons (electron current). Conventional current propagates at very nearly the speed of light in the medium. The movement of electrons, on the other hand, is slow (only a few inches an hour in copper wire) even for direct current, and in alternating current the electrons have not net movement at all.

Stranger