Ion

An ion is a charged particle formed from a molecule or atom by the loss or acquisition of one electron. It follows that the number of protons in an ion is not equal to the number of electrons. After studying the article, you will learn what charged particles are, what ions, cations and anions are, as well You will be able to find out by the number of the element how much charge it can have.

Number of electrons in an ion

The number of electrons in a neutral atom is equal to the number of protons in the nucleus, for example, chromium (₂₄Cr) has 24 protons, respectively, 24 electrons rotate around the nucleus. As described in the article "electronic configuration of the atom", each the electron moves along a certain orbital, that is, it has a given amount of energy.

If an ion is formed due to the loss of an electron, then the charge of the ion becomes positive (the electron has a negative charge), a scheme for memorizing:

₂₄Cr - e^- = ₂₄Cr + e⁺ = ₂₄Cr⁺
₂₄Cr - 3e^- = ₂₄Cr + 3e⁺ = ₂₄Cr³⁺

Similarly , when an electron is attached:

₂₄Cr + e^- = ₂₄Cr - e⁺ = ₂₄Cr^-
₂₄Cr + 3e^- = ₂₄Cr - 3e⁺ = ₂₄Cr^3-

Ionization energy

If the electron is given enough energy, then the electron will "break away" from the atom. The closer the electron is to the core - the more difficult it is to tear it off, which means that more energy needs to be transferred. The energy required for separation The electron is called the ionization energy or ionization potential (I). The values of I are tabulated and can be found in various reference books.

Electron affinity energy

Also, electrons can attach to an atom, in the process of attaching an electron releases energy, such energy is called the electron affinity energy , for each electron of a particular atom, the affinity energy is numerically equal to and it is opposite in sign of the ionization energy, for example, ₁₇Cl, in order to tear off the 17th electron from the atom chlorine, it is necessary to inform him of 13 eV, any other electron that will join in place of the 17th electron it will also allocate 13 eV.

Cations and anions

Atoms in which the number of protons is not equal to the number of electrons are called ions, because an electron has negative charge, then if there are more electrons than protons, then the total charge is negative: S^2- it means that in a given sulfur atom the number of electrons is more than protons per two electrons. Accordingly, if there are fewer electrons than protons, then the total charge is positive and is denoted H⁺. Negatively charged atoms are called anions, positively charged atoms are called cations.

What charge will the atom have?

Theoretically, it is possible to take away all the electrons from an atom, but this is possible only in laboratory conditions and for outside the laboratory, atoms will not be in such a state, why?

Let's return to the electronic shell device. Around the atom, the electrons are grouped by energy levels, each filled level shields the nucleus and is more stable than not fully filled level. That is, the electronic configuration tends to the state of the filled sublevel: if on the p-shell if there are 5 electrons, then the atom is more likely to accept one electron than to give five. So, for example, the atom chlorine, five electrons at the 3p sublevel, the affinity energy of chlorine is 3.61 eV, the ionization energy is 13 eV. In sodium at the last sublevel there is one electron, the affinity energy is 0.78 eV, the ionization potential is 0.49 eV, therefore it is more likely that sodium will give up one electron than accept it.

Knowing the ionization potential and affinity energy, we can make an assumption about the interaction of substances. If mix sodium and chlorine, and give them energy, then most likely Na will give one electron to Cl and the result will be a mixture of Na⁺ and Cl^- ions.

Example

So you can guess by the number of the element what charge it will have, for example, the 19th element, electronic configuration - 1s ²2s²2p ⁶3s ²3p⁶4s ¹, most likely, such an element can either give away or accept one electron. The electronic configuration of the 27th element looks like this: 1s ²2s ²2p ⁶3s ²3p⁶4s ²3d⁷, the d-sublevel can have 10 atoms in total, i.e. either the atom will accept 1,2 or 3 electrons, or it will give away 1,2,3...7 electrons, so, most likely, it will take 3, i.e. the possible states are +1, +2 and +3,

Now you know what ions are, it remains to study the chemical bond and you will be able to compose redox reactions!