How do you tell if an atom has a positive or negative charge?

Question

How do you tell if an atom has a positive or negative charge?

Answer 1

By definition, all atoms have a net charge of zero and therefore they do not have an overall positive charge or a negative charge. However, because atoms are made up negatively charged electrons AND positively charged protons, and because electrons are easily transferred from one atom to another, it is possible to end up with a surplus of electrons, resulting in a negative charge, or a deficit of electrons, resulting in a positive charge. So, in other words, what you have to do is add up the number of electrons and add up the number of protons. This is how you determine the net charge.

By the way, as I mentioned, by definition, all atoms have a net charge of zero because the number of electrons always equals the number of protons. However, if the number of electrons does not equal the number of protons you no longer have an atom. Instead, this is referred to as an ion. Ions come in what I like to call two flavours - positive and negative. The positive ions are called cations and the negative ions are called anions.

Having stated all this, if an atom were to lose an electron, which is negatively charged, you end up with a positively charged ion - a cation. Similarly, if an atom were to gain an electron, which as mentioned is negatively charged, you end up with a negatively charged ion - an anion.

Atoms tend to lose or gain up to 3 electrons, although they can lose or gain more than this. Therefore, it is common to have ions (cations or anions) with charges of +1, +2, +3, or -1, -2, and -3.

A common example of this is when a sodium (Na) atom loses 1 electron to become a sodium ion (Na+). Another common example is when a chlorine (Cl) atom gains 1 electron to become a chloride ion (Cl-). Incidentally, if these two ions come in close proximity of each other they will be attracted to each other and an ionic bond will form between them. This will result in a molecule of NaCl (sodium chloride) being formed and as you probably know, NaCl is also known as table salt.

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Answer 2

well from the atomic number it's possible 2 du so

if durin' reactions it gains electrons then it is negative and if it loses electrons then it becomes positive

Answer 3

from the number of protons and electrons in the atom, or the atomic number