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Aluminum Ion Charge And Formula

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The charge of an aluminum ion is typically 3+. This is because the element’s atomic number is 13, reflecting the fact that it has 13 electrons and 13 protons. The valence shell of aluminum has three electrons, and per the octet rule, these three electrons are lost resulting in just 10 electrons and 13 protons. Aluminum then has three excess protons so the charge of a base aluminum ion is 3+.

That’s the quick answer regarding how aluminum’s charge is 3+. Yet to better understand the relationship between ions, ionization, and the different elements, a closer look at both positive and negative ions is needed.

Facts About Aluminum

Aluminum is a soft metal in the boron group on the periodic table of elements. It is represented with the symbol “Al” and it has the atomic number 13. Aluminum is an extremely abundant element, in fact, it is the most abundant metal element in the crust of the earth. Along with iron, aluminum is the most commonly used metal.  In the year 2016, the global production of aluminum was around 59 million metric tons. Aluminum is used for a wide variety of different purposes, including the creation of vehicles, batteries and packaging materials, as well as the construction of buildings and the creation of cooking utensils.

The Structure Of An Atom

Atoms are made out of three basic parts, separated into two distinct regions. Neutrons, electrons, and protons are the three constituent parts of an atom. Protons are positively charged subatomic particles, while neutrons are subatomic particles that have no charge. Neutrons and protons have masses that are approximately equal. Neutrons weigh around 1.67 x 10-24 grams.

The first region of the atom is the nucleus, the center of the atom. The nucleus is comprised of neutrons and protons. Outside of the nucleus is the orbital region, consisting of electrons which orbit the nucleus. The outermost portions of the atom are referred to as the electron shells. These electron shells hold electrons in orbit and an atom can have multiple electron shells.


Atoms have different properties based on how the simple constituent particles are arranged. The atomic number of an element is based upon the number of protons an atom of that element has. If an atom of an element is neutral, that means it has the same number of electrons and protons. The number of neutrons that an element has defines the isotopes of that element. Isotopes are simply different variants of the prime element’s atoms, differing only in the number of neutrons possessed by the atom.

When taken together, the element’s mass number is determined by the number of protons and neutrons in an atom of the element. Isotopes of an element have mass numbers which are slightly different because they differ in their number of neutrons. The atomic mass of an element is discerned by taking the mean of mass numbers for the different isotopes of an element. While isotopes are forms of elements that differ due to the different number of neutrons in the nuclei, ions are atoms that have a net electrical charge because the base atom of the element has gained or lost one or more electrons.

Definition Of An Ion

Ions are molecules or atoms that have lost or gained one or more electrons from their valence shell, which ends up giving them a net negative or positive electrical charge. To put that another way, ions have an imbalanced number of electrons and protons in a chemical species. The term ion was initially coined by the English chemist Michael Faraday to describe chemicals which travel from one electrode to another.

Negative And Positive Ions

Shows how a helium atom contains a single proton and electron, and how it can become a cation or anion. Photo: By Jkwchui – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12617370

Pure atoms don’t have an electric charge, and this is due to the fact that the atoms possess an equal number of electrons and protons. Electrons have a negative charge, while protons are subatomic particles with a positive charge. However, certain situations and chemical interactions can cause atoms to shed an electron or gain an electron, which affects their net charge. In this case, the atoms which have their net charge affected become ions.

As an example, an aluminum atom has an atomic number of 13, reflecting the fact that it has 13 protons. Every proton has a positive charge, and since most atoms are neutral it follows that for every proton that there is an electron, for 13 electrons and 13 protons. This is true of all atoms of aluminum. Metals are capable of forming ions by losing electrons, and this is true of aluminum which can lose three electrons.

If the result of a change in charge produces a positive ion, the ion is referred to as a cation. Cations are denoted by the element that comprises them, so in this instance, there is an aluminum cation.

In the particular example of aluminum, aluminum had an initial charge of zero, thanks to the 13 electrons and 13 protons canceling one out. When an aluminum atom becomes an ion, it drops three electrons. Since there are only 10 electrons, their value is subtracted from the number of protons, and the difference is a positive three. Therefore, an ion of aluminum has a positive charge of three, shown as 3+. Some chemistry books may put the “+” symbol before the number rather than after the number. The cationic version of aluminum can also be displayed with a plus sign and a superscript number: Al^+3 or Al^3+.

As for negatively charged ions, these are referred to as anions. Anions are the result of a charge change that leaves a negative charge overall. As you might expect, the representation of an anion is with a negative sign instead of the positive sign of the cation. As an example, Cl- is a chlorine anion created when chlorine picks up another electron, which gives it a net charge of -1. Unlike cations, which are just called cations of the respective elements, anions have a special naming scheme (so an anion of chlorine isn’t referred to as a chlorine ion).

If an ion is made out of single element, then this is denoted by appending the suffix “-ide” to the name of the element, so a chlorine anion becomes chloride, and an ion of carbon and nitrogen or CN- becomes cyanide. In most cases, the “-ide” suffix is sufficient. However, if there are ions made out of more than one element (referred to as polyatomic anions) or anions which contain oxygen, more suffixes and prefixes are needed. The suffix “-ate” is applied to oxyanions that have the typical number of oxygen atoms within them. Meanwhile, the suffix “-ite” is applied to oxyanions that have one less oxygen than the norm.

For oxyanions that have two fewer oxygens than the norm, yet have a minimum charge, the element base is appended into the middle of a “-hypo” prefix and an “-ite” suffix. Meanwhile, for oxyanions that have one oxygen atom more than the standard, yet still have normal charge, the per prefix is appended to it as well as the “-ate” suffix. Finally, the anions that have sulfur substituting for oxygen are given the prefix “thio-“.

The ionization energy trends for elements on the periodic table. Photo: By Sponk (PNG file)Glrx (SVG file)Wylve (zh-Hans, zh-Hant)Palosirkka (fi)Michel Djerzinski (vi)TFerenczy (cz)Obsuser (sr-EC, sr-EL, hr, bs, sh)DePiep (elements 104–108)Bob Saint Clar (fr)Shizhao (zh-Hans)Wiki LIC (es)Agung karjono (id)Szaszicska (hu) – Own work based on: Erste Ionisierungsenergie PSE color coded.png by Sponk., CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=24696016

Different elements are capable of giving rise to ions in a number of different ways, something which isn’t surprising when considering how many different families there are on the periodic table of the elements. However, because it is possible for these many elements to be grouped into families (given the group or column they are found in on the periodic table), it’s possible that the way these elements will create ions can be predicted. A few heuristics can be used to predict the creation of ions.

In general, alkali metals, those found in group one of the periodic table create 1+ ions when they ionize. As an example, Li+ is that the ion of lithium. The alkaline earth metals, those found in group 2 of the periodic table, ionize to 2+ cations. Beryllium makes Be 2+ ions. Most of the metals found in group 3 of the periodic table, such as indium, gallium, and aluminum ionize to form 3+ cations. The aluminum cation, as seen above, is defined as Al 3+. The group 6 metalloids and nonmetals such as oxygen, tellurium, selenium, and sulfur produce 2- anions when they ionize. For instance, the stable, ionized state of oxygen is given as O2-. The elements found in group 7 of the periodic table, produce anions of -1 when they ionize. For this reason, the anion of fluorine would be given as Fl-.

Pure metals, that is to say, non-transition metals, will always end up forming cations or positive ions. In fact, one of the defining traits of metals is that metals tend to shed electrons. In contrast, transition metals or metalloids may form ions with various charge intensities, and classifying the numerous ways these cations are formed is more complex than pure metals.

While metals usually form cations, nonmetals usually gain electrons and form anions. Similar to how metals lose electrons, a defining property of nonmetals is that they often gain electrons. The reasons that these metals and nonmetals gain or lose electrons has to do with a number of complex factors. Some of the factors influencing the ionization of elements include the number of valence electrons each atom has and the octet rule chemical bonding.


About The Author

Daniel obtained his BS and is pursuing a Master's degree in the science of Human-Computer Interaction. He hopes to work on projects which bridge the sciences and humanities. His background in education and training is diverse including education in computer science, communication theory, psychology, and philosophy. He aims to create content that educates, persuades, entertains and inspires.