A rare-earth metal is a group of fifteen metallic elements that are located in the periodic table between lanthanum and lutetium. They are called rare-earth because they are not very abundant in the Earth’s crust.
They are also not very abundant in the Periodic Table, as they are organized in the d-block along with zinc, cadmium, and mercury. This makes them structurally similar, which is part of why they can be efficiently separated using chromium.
These fifteen elements have an inner electron configuration of [Kr]4d6. This means that the element has a outermost shell consisting of six electrons. When an element has this configuration, it is susceptible to oxidation, or losing its electrons. When this happens, a compound containing the element can form a 3+ ion.
Chlorine
Chlorine is a chemical element that has the symbol Cl and atomic number 17. It is a pale-green gas at room temperature. Chlorine is a highly reactive element, so it is rarely found pure in the environment.
Chlorine is an essential part of many elements and molecules that are necessary for life. For example, chlorine forms part of our stomach acids that help break down what we eat.
Several million metric tons of chlorine are produced each year as a byproduct in various industries, including the production of plastics and fumigation agents. Much of this chloride ends up in water sources and soil, where it can persist for years.
A large amount of chlorine in our atmosphere comes from chlorofluorocarbons (CFCs), chemicals once used in refrigerators and aerosol sprays. These compounds have been banned since the 2000s due to their harmful effects on the ozone layer.
Bromine
Bromine is a halogen that has an electronegativity of 3.0. It has seven electrons in its outer shell, two in the next shell inward, and one in the innermost shell.
Bromine most commonly forms three-electron bonds, also known as iodides. When it does form a compound with more than three atoms, it is typically a binary compound with an electride bond. Bromine can form up to six atoms per molecule in this manner.
Bromine can form compounds with metals that have lower atomic numbers than it does. For example, bromine can form a four-electron chloride with mercury(II) ions. It can also form a binary compound with zinc oxide called bromoxynol.,
The hardest part about working with bromine is collecting it from the reaction mixture after the reaction has taken place.
Iodine
Iodine is a halogen element that is typically brown or black in color. It is one of the hardest elements to break down, so it is not very soluble in liquids.
Iodine is used to form iodide ions, which are more soluble. Iodide ions form when iodine reacts with a base like sodium hydroxide. This reaction produces the iodide ion and eliminates the sodium atom.
Iodine itself does not form compounds that contain nine electrons in its outer shell. When iodine molecules break down, however, they produce atoms with a total of nine electrons in their outer shells.
Iodine oxide forms when iodine breaks down and has the electron configuration [Kr]4d6-. This confirms that iodine forms a 3+ ion that has the electron configuration [Kr]4d6-.
Potassium
A significant difference between the chemical properties of potassium and caesium is that potassium forms ionic compounds with many other elements. It does not tend to form purely atomic compounds like caesium does.
This property makes it a little more stable than caesium, as it can bond with more elements to form compounds. These compounds can be found in nature, as well as in research and industrial settings.
Like all of the halogens, chlorine forms a compound with potassium: potassium chloride. This salt is found naturally, and it is used in the food industry as a preservative and flavoring agent. It is also a source of dietary potassium.
Potassium sulfate is another common compound that contains the element. It is used to manufacture soap, and it helps to dry out the soap so that it can lather up.
Hydrogen
A hydrogen ion, or a proton, is the nucleus of a hydrogen atom. When a hydrogen atom loses an electron, it becomes a positively charged hydrogen ion.
Hydrogen ions can form when a chemical compound containing hydrogen undergoes oxidation-reduction (redox) reactions. In this case, the chemical compound is oxidized, or loses electrons, and H+ ions are produced.
Chemists use the symbol H to represent hydrogen ions. An equation showing the formation of H+ ions during redox reactions would look like this:
This reaction shows that the blue substance being oxidized (i.e., losing electrons) is chlorine and that the product of the reaction is hydrochloric acid (HCl).
Lithium
Lithium is a chemical element with the symbol Li and atomic number 3. A light metal, lithium is found in few naturally occurring minerals, the most common of which is spodumene.
Lithium is used in lens materials for optical glasses, in nuclear technology, and as a pharmaceutical compound. Its uses as a battery component and in solar panels are growing rapidly.
The element was named after the Greek word lithos, meaning stone. This is due to the elemental composition of lithium being similar to common stones such as granite.
Three isotopes of lithium are synthesized in nature: 6Li, 7Li, and 8Li. However, only 6Li is stable whereas the other two are unstable nuclides that convert into different elements.
Like all alkali metals, lithium naturally expels an electron from its outermost shell to form a charged ion. In this case, it forms a Li+ ion with one valence electron.
Sodium
Sodium is a metal that can form a +2 ion and a +1 ion. Both of these ions can be referred to as sodium ions. A sodium ion has an electron configuration of [Ne]3s1.
Sodium can be used in place of potassium in some compounds, like table salt. This is because it has an identical electron configuration, but it is a different element.
Sodium is a very common element in the Earth’s crust. It makes up about 2% of the Earth’s mass and over 75% of the Earth’s mass is oxygen. It is therefore more abundant than potassium by quite a bit!
Like all the elements mentioned before it, sodium is an alkali metal. It has a very high electropositivity which means it gives off a lot of electrons when it reacts with other substances.
Magnesium
Magnesium is the next element in the periodic table. Like calcium, magnesium is a common metal that is found in nature. It is also widely produced through industrial production.
Magnesium is one of the metals that has a 3+ ion that has the electron configuration [Kr]4d6. This configuration refers to the number of electrons in the neutral atom, not what it looks like!
Magnesium ions are formed when magnesium reacts with another compound or ion. For example, when magnesium reacts with hydrochloric acid (HCl), it forms the ionic compound MgCl. When it reacts with ketone, it forms the ionic compound Mg(C2H5)2.
Like calcium, magnesium can be used in agriculture and industry due to its abundance and properties such as hardness and durability.
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