Boron group facts for kids

↓ Period
2	Boron (B) 5 Metalloid
3	Aluminium (Al) 13 Other metal
4	Gallium (Ga) 31 Other metal
5	Indium (In) 49 Other metal
6	Thallium (Tl) 81 Other metal
7	Nihonium (Nh) 113 other metal
Legend primordial element synthetic element

The boron group is a family of chemical elements found in Group 13 of the periodic table. This group includes boron (B), aluminium (Al), gallium (Ga), indium (In), thallium (Tl), and the man-made element nihonium (Nh). These elements are special because they all have three valence electrons, which are the electrons in their outermost shell. Sometimes, they are also called the triels.

Some elements in the boron group play roles in nature. Boron is a tiny but important nutrient for many plants. Too little or too much boron can harm plants. Aluminium is common but doesn't have a known role in living things and is generally safe. Gallium and indium can help with metabolism, which is how our bodies use energy. Thallium, however, is very dangerous. It can stop important body processes and was once used to control pests.

Exploring Boron Group Characteristics

Like other groups in the periodic table, the elements in the boron family show clear patterns. These patterns appear in how their electrons are arranged and how they behave chemically.

The boron group is interesting because of how its elements' properties change. For example, boron is very different from the others. It is one of the hardest elements, almost as hard as a diamond. Boron is a metalloid, meaning it has properties of both metals and non-metals. The other elements in the group are all metals. Boron also has a much higher melting point (2076 °C) than aluminium (660 °C), which is the next highest.

Chemical Behavior of Boron Group Elements

The elements in the boron group show different levels of chemical activity. Generally, as the elements get heavier, they become more reactive.

How They React with Hydrogen

Boron, the first element, usually doesn't react much with other elements unless it's very hot. However, it can form many compounds with hydrogen, called boranes. A simple example is diborane (B₂H₆).

As we go down the group, elements like aluminium and gallium form fewer stable compounds with hydrogen. For instance, AlH₃ and GaH₃ exist. Indium forms even fewer, and no stable compound of thallium with hydrogen has been made in a lab.

Understanding Oxides in the Boron Group

All elements in the boron group can form a type of compound called a trivalent oxide. In these compounds, two atoms of the element join with three atoms of oxygen. These oxides show a trend in their pH levels, moving from slightly acidic to basic.

Boron trioxide (B₂O₃) is a bit acidic. Aluminium oxide (Al₂O₃) and gallium(III) oxide (Ga₂O₃) are amphoteric, meaning they can act as both acids and bases. Indium(III) oxide (In₂O₃) is almost amphoteric, and thallium(III) oxide (Tl₂O₃) is a base. These compounds are generally stable, though thallium oxide breaks down at very high temperatures.

A powdered sample of boron trioxide (B₂O₃), one of the oxides of boron

Compounds with Halogens

The elements in Group 13 also form stable compounds with halogens, like fluorine and chlorine. These compounds usually have the formula MX₃, where M is a boron-group element and X is a halogen.

Fluorine can form stable compounds with almost all elements, including those in the boron group. Scientists even think that nihonium could form a compound with fluorine, NhF₃, before it quickly decays. Chlorine also forms stable compounds with all boron group elements. Bromine and iodine also react with these elements, though sometimes less strongly.

Physical Properties of Boron Group Elements

The elements in the boron group share some similar physical properties, but boron often stands out. For example, all elements in this group except boron are soft. Also, the metals in Group 13 are quite reactive at normal temperatures, while boron needs very high temperatures to react similarly.

One thing they all have in common is three electrons in their valence shells. Boron, being a metalloid, doesn't conduct heat or electricity well at room temperature. However, it becomes a good conductor at high temperatures. The other metals in the group are good conductors under normal conditions. This fits the general rule that metals conduct heat and electricity better than most non-metals.

Understanding Oxidation States

The elements in Group 13 can exist in different oxidation states, which describe how many electrons they have gained or lost. For lighter elements like boron and aluminium, the +3 state is usually the most stable. However, for heavier elements like thallium, the +1 state becomes more common and stable.

Boron and aluminium can also form compounds with +1 or +2 oxidation states. Gallium and indium can have +1, +2, or +3 states. Thallium is mostly stable in the +1 state, though +3 compounds are also known.

Periodic Trends in the Boron Group

We can see clear trends in the properties of the boron group elements. For example, their boiling points generally decrease as you move down the group. On the other hand, their densities tend to increase.

The 5 stable elements of the boron group

Nuclear Properties of Boron Group Elements

All the natural elements in the boron group have stable isotopes, which are different forms of an element with varying numbers of neutrons. Nihonium, being man-made, does not have any stable isotopes.

Boron, gallium, and thallium each have two stable isotopes. Aluminium and indium are monoisotopic, meaning they have only one stable isotope. However, most indium found in nature is a slightly radioactive isotope called ¹¹⁵In.

Like all elements, the boron group also has radioactive isotopes. These are either found in tiny amounts in nature or created in labs. The longest-lasting radioactive isotope in this group is ¹¹⁵In, with an incredibly long half-life of 4.41 × 10¹⁴ years. The shortest-lived is ⁷B, which lasts for only a tiny fraction of a second.

A Look Back: History of the Boron Group

The boron group has had different names over time, including Group IIIB or IIIA in older systems. The name "triels" comes from the Latin word tri- (meaning "three"), referring to the three valence electrons these elements share. This name was suggested in 1970.

The Discovery of Boron

Ancient Egyptians knew about boron in the mineral borax. But pure boron wasn't isolated until 1808. That year, Humphry Davy used electrolysis to extract it. He passed an electric current through a boron compound dissolved in water, separating the elements. Davy called it boracium. Around the same time, French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard also produced boron.

Uncovering Aluminium

Like boron, aluminium was first known in minerals such as alum. Many scientists, including Antoine Lavoisier and Humphry Davy, tried to extract it. Davy even gave the metal its current name. In 1825, Danish scientist Hans Christian Ørsted successfully prepared an impure form. Friedrich Wöhler improved the process two years later. The first pure sample was made by Henri Etienne Sainte-Claire Deville. At one point, aluminium was considered as precious as gold and silver! Today, aluminium is produced using electrolysis of aluminium oxide, a method developed by Charles Martin Hall and Paul Héroult in the late 1880s.

Finding Thallium

Thallium, the heaviest natural element in the boron group, was discovered in 1861 by William Crookes and Claude-Auguste Lamy. Unlike some other elements, thallium was found before Dmitri Mendeleev created the periodic table. Crookes and Lamy were studying residues from sulfuric acid production. They noticed a new, deep green line in the spectrum. Crookes named it after the Greek word thallos, meaning a green shoot. Lamy then produced larger amounts and studied its properties.

The Story of Indium

Indium is the fourth element in the boron group. It was discovered in 1863 by Ferdinand Reich and Hieronymous Theodor Richter. They were examining a mineral called sphalerite (also known as zinc blende) for signs of thallium. Instead of thallium's green lines, they saw a new, deep indigo-blue line in their spectroscope. They realized it was a new element and named it "indium" after this characteristic indigo color.

The mineral zinc blende, more commonly known as sphalerite, in which indium can occur.

Discovering Gallium

Gallium was discovered in August 1875 by French chemist Paul Emile Lecoq de Boisbaudran. Interestingly, Dmitri Mendeleev had predicted its existence six years earlier! While looking at zinc blende, Boisbaudran found signs of a new element. Within three months, he produced a sample and purified it. He presented his findings to the French Academy of Sciences, naming the new element after Gaul, the ancient name for France.

Creating Nihonium

Nihonium, the last confirmed element in the boron group, was not found in nature but created in a laboratory. Its creation was first reported in 2003 by a team from the Dubna Joint Institute for Nuclear Research in Russia and the Lawrence Livermore National Laboratory in the United States. Nihonium was discovered as a product of the decay of another element, moscovium. Later, experiments by RIKEN in Japan in 2004 directly created nihonium, and this was recognized as its official discovery. The name "Nihonium" comes from Nihon, the Japanese word for Japan.

Where the Names Come From

The name "boron" comes from the Arabic word boraq for the mineral borax. The "-on" ending might come from "carbon." "Aluminium" was named by Humphry Davy and comes from the Greek alumen or Latin alum. "Gallium" is from the Latin Gallia, for France. "Indium" comes from the Latin indicum, meaning indigo dye, referring to its blue spectroscopic line. "Thallium" is from the Greek thallos, meaning a green twig. "Nihonium" is named after Japan (Nihon).

Where Boron Group Elements Are Found

The elements in the boron group are found in different amounts in the Earth's crust.

Boron's Presence in Nature

Boron is a very light element and is rarely found on its own in nature. It makes up only a tiny part (0.001%) of the Earth's crust. However, it is found in over a hundred different minerals and ores. The main source is borax, but it's also in minerals like colemanite and kernite. Major countries that mine boron include Turkey, the United States, and Argentina. Turkey is the biggest producer, accounting for about 70% of the world's boron.

Aluminium's Abundance

In contrast to boron, aluminium is the most abundant metal in the Earth's crust, and the third most abundant element overall. It makes up about 8.2% of the Earth's crust, found more than any element except oxygen and silicon. Like boron, it's rarely found as a free element because it easily combines with oxygen. Aluminium is found in many minerals, but its main source is the ore bauxite. Leading countries in aluminium extraction include Ghana, Suriname, and Russia.

Gallium's Rarity

Gallium is a relatively rare element in the Earth's crust, making up only 0.0018%. Its production has grown as extraction methods have improved. Gallium is often found in small amounts in other ores, like bauxite and sphalerite, and in minerals such as diaspore. Tiny amounts have even been found in coal. Some minerals, like gallite, have more gallium, but they are too rare to be major sources.

Indium's Scarce Occurrence

Indium is another rare element in the boron group, making up only 0.000005% of the Earth's crust. Very few minerals contain indium, and they are all scarce. Indium is found in small quantities in several zinc ores, as well as some copper and lead ores. Extraction methods have become more efficient, leading to larger yields. Canada has the largest indium reserves, with the United States and China also having significant amounts.

Thallium's Presence

Thallium has a moderate abundance in the Earth's crust, estimated at 0.00006%. It is found in some rocks, soil, and clay. Many sulfide ores of iron, zinc, and cobalt contain thallium. It's also found in minerals like crookesite (where it was first discovered) and lorandite.

A small bundle of fiberglass

Nihonium: A Lab-Made Element

Nihonium is an element that is never found in nature. It has only been created in laboratories. Because of this, it is called a synthetic element and has no stable forms.

Everyday Uses of Boron Group Elements

All the natural elements in the boron group have many uses in various products and industries.

Boron's Many Applications

Boron has become very important in industry. A common use is in fiberglass. It's also used in borosilicate glass, which is special because it resists heat changes much better than regular glass. Boron and its compounds are also used in ceramics. You might find boron in pots, vases, plates, and ceramic pan-handles because of its insulating properties.

The compound borax is used in bleaches for clothes and teeth. Boron's hardness also gives it many other uses. A small amount of boron is used in agriculture to help plants grow.

Aluminium's Widespread Uses

Aluminium is a metal with many familiar uses in our daily lives. It's often used in construction materials and electrical devices, especially as a conductor in cables. It's also used for cooking tools and food containers because it doesn't react with food.

Aluminium reacts strongly with oxygen, releasing a lot of heat. This property makes it useful in welding. It's also a key part of alloys used to make lightweight parts for aircraft and cars. You can also find aluminium in decorations and various electronic devices.

Gallium's Role in Technology

Gallium and its compounds have found many uses in recent years. Gallium arsenide is used in semiconductors, amplifiers, and solar panels for things like satellites. Gallium alloys are often used in dentistry.

A major use of gallium is in LED lighting, especially blue LEDs. Pure gallium can be added to semiconductors to change their properties. Gallium can also "wet" glass and porcelain, making it useful for creating mirrors and other reflective objects. Adding gallium to other metals can lower their melting points.

Gallium is one of the chief components of blue LEDs

Indium's Important Coatings

Indium's uses fall into a few main areas. The largest part (70%) is used for coatings, often as indium tin oxide (ITO). A smaller amount (12%) goes into alloys and solders. A similar amount is used in electrical parts and semiconductors. The rest is for other minor uses.

Indium can be found in platings, bearings, display devices, and heat reflectors. Indium tin oxide is very important and is used in glass coatings, solar panels, streetlights, and many types of electronic displays.

Thallium's Specialized Applications

Thallium is used in its pure form more often than other boron-group elements. It's found in low-melting glasses, photoelectric cells, and switches. It's also used in mercury alloys for thermometers and in thallium salts. You might find it in lamps and electronics, and it's used in medical imaging of the heart.

Thallium sulfate (Tl₂SO₄) was once used to control pests like rats and mice. However, due to its extreme danger to humans, many countries, including the United States, banned its use in pesticides starting in 1975.

Biological Role of Boron Group Elements

None of the Group 13 elements have a major biological role in complex animals. However, some are connected to living things. Generally, lighter elements have more biological roles than heavier ones. The heaviest elements in this group are often toxic.

Boron is essential for most plants. Their cells use it to strengthen cell walls. Boron is also found in humans as an essential trace element, and scientists are still studying its full importance in human nutrition. It can interact with important molecules like carbohydrates.

Aluminium has no known biological role in plants or animals, even though it's very common. Gallium is not essential for humans, but it can attach to proteins that carry and store iron. Gallium can also help stimulate metabolism. Indium and its heavier relatives have no known biological role, though small amounts of indium salts might stimulate metabolism.

Understanding Toxicity of Boron Group Elements

Each element in the boron group has a different level of toxicity for plants and animals.

For example, too much boron can harm plants like barley. Symptoms of boron toxicity in plants include slower cell division, reduced growth of shoots and roots, and less chlorophyll in leaves.

Aluminium is not very toxic in small amounts, but very large doses can be slightly harmful. Gallium is generally not considered toxic, though it might have minor effects. Indium is also not toxic and can be handled safely, but some of its compounds can be slightly to moderately toxic.

Thallium, unlike gallium and indium, is extremely dangerous. Even tiny amounts can cause serious harm, like hair loss all over the body and damage to many organs. Because of its high toxicity, thallium compounds were once used to control pests like rats. However, due to the serious risks to humans, many countries, including the USA, banned its use in pesticides starting in 1975.

Nihonium is a highly unstable element that decays by giving off alpha particles. Because it is so radioactive, it would definitely be extremely toxic. However, only a few atoms of nihonium have ever been created.

See also

In Spanish: Grupo del boro para niños