In this lesson, discover what it means to be a monatomic ion and learn some helpful examples. Then you will learn the naming convention for monatomic ions.
What is a Monatomic Ion?
Individuals that have played with magnets might know that two oppositely charged magnets will stick to each other, while two magnets of the same charge will repel each other. Well, think of a single, charged magnet as a monatomic ion.
Monatomic ions can be positive or negative and just like magnets, oppositely charged ions will attract, and ions with the same charge will repel each other.
A good way to remember this definition is to break the term monatomic ion into its component parts. The prefix mon- or mono– means one. The suffix –atomic refers to an atom. Thus monatomic means one atom.
The term ion means charged particle. Combined, we have our definition for monatomic ion. A monatomic ion is a charged particle that consists of only one atom.The charge on the ion may be positive or negative. Additionally, the size of the charge may vary; for example, some ions have a 1- charge (like on a chlorine atom) while others, like a nitrogen atom, are capable of carrying a 3- charge. Similarly, some ions can carry a 1+ charge (like sodium), and others can have up to a 4+ charge (like vanadium)! Many atoms are capable of having multiple charges. Copper, for example, can have a 1+, 2+ or 3+ charge.
Monatomic ions are chemically represented by the element’s symbol with the size and type of charge written as a superscript to the right of the symbol. If the size of the charge is one, then the type of charge (+ or -) is all that is written.For example, the magnesium 2+ ion is written as Mg2+.The fluorine 1- ion is written as F–.
Positive vs. Negative Ions
Positively charged ions are called cations. Negatively charged ions are called anions.
Can all elements form both cations and anions? The answer is no! With the exception of hydrogen, single elements generally only form one type of ion. Metal elements always form cations, non-metals always form anions. The periodic table provides reference for distinguishing metals from nonmetals.
Metals are elements that are generally shiny, silvery, good conductors of heat and electricity and solid at room temperature. They are located on the left side and middle region of the periodic table.
They are separated from non-metals by the thick dark staircase on the right side of the periodic table. Non-metals are elements that are poor conductors, they are variously colored and generally exist as a gas at room temperature.Many of the transition metals, located in the middle of the periodic table are capable of forming differently charged cations.
Hydrogen, up in the top left corner is special in that it can be either a 1+ cation or a 1- anion!There are some tricks to remembering what kind of ion elements are likely to form. Elements in group one (column 1 of the periodic table) always form 1+ ions. Elements in group 2 (column 2) always form 2+ ions. Elements in group 7 (column 17 of the periodic table) always form 1- ions. The noble gases, which are all the way to the right on the periodic table (group 18) never form ions.
A chart is a good way to view common monatomic ions by charge.
Naming Monatomic Ions
Naming monatomic ions is wonderfully easy.When naming monatomic cations, all you need is the name of the element accompanied by the term ion. For example:
- The magnesium 2+ ion (Mg2+) is simply called the magnesium ion.
- The lithium 1+ ion (Li+) is the lithium ion.
If your monatomic cation is also a transition metal, give the name of the element followed by the magnitude of the charge written in Roman numerals. Follow the Roman numerals with the term ion.
- The iron 3+ ion (Fe3+) would be called the iron (III) ion.
- The copper 2+ ion (Cu2+) would be called the copper (II) ion.
Naming monatomic anions gets a little fancier.
To begin, take the root of the element name (generally the first syllable) and add the ending -ide. Add the term ion to finish! Examples of monatomic anions look like this:
- The chlorine 1- ion (Cl–) becomes the chloride ion.
- The oxygen 2- ion (O2-) becomes the oxide ion.
A monatomic ion is a charged particle that consists of one atom.
The charge on the particle may be positive or negative and the magnitude of the charge will vary.Monatomic ions that are positively charged ions are called cations. Negatively charged ions are called anions. Cations form from metals; anions form from non-metals.
Hydrogen can form either a cation or an anion.When naming cations, simply take the name of the element and add the term ion to the end. If the cation is formed from a transition metal, give the name of the element followed by the magnitude of the charge written in Roman numerals.
Add the term ion to the end. The lead 2 ion is an example of a cation.When naming anions, take the root of the element name and add the ending -ide and add the term ion to finish. An example of anion is the chloride ion.