Group 6a: Chalcogen Elements and Properties

Kelly Barkers, Julie Zundel
  • Author
    Kelly Barkers

    Kelly taught 7th grade science for 5 years and served as the Science Department Chair. She graduated from Cedar Crest College with a bachelor's degree in biology and a minor in health and wellness. While attending college, she was a peer tutor for Anatomy and Physiology.

  • Instructor
    Julie Zundel

    Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

Learn about the chalcogen family of elements, their properties, chemical reactions, and uses. Updated: 10/10/2021

Chalcogens: Group 6a Periodic Table

Elements on the periodic table are arranged in specific columns that all share similar chemical properties. For example, the chalcogens located in Group 6a (or Group 16, depending on the periodic table), share properties that cause them all to chemically react with other elements in a similar manner. The chalcogens are found in the third column from the right on the periodic table.

The chalcogens are located on the right side of the periodic table and begin with the element oxygen.

Periodic Table

Another name for the chalcogens is the "oxygen group" or "oxygen family," since oxygen is found at the top of the column. The elements within a particular column are arranged from top to bottom in order of increasing atomic number, which represents the number of positively charged protons in the dense center of the atom.

The chalcogens are:

Element Name Element Symbol Atomic Number
oxygen O 8
sulfur S 16
selenium Se 34
tellurium Te 52
polonium Po 84
livermorium Lv 116

The word "chalcogen" is derived from the Greek words chalcos and gen, where "chalcos" means "ore," and "gen" means "to form." This highlights the fact that the majority of the chalcogens are able to form ores with other elements. Ores are compounds that usually contain a type of metal or mineral. For example, one of the most abundant ores, magnetite, contains the metal iron.

Chalcogens

Although what I am about to tell you sounds like a story out of a movie, it really happened. In November 2006, a former KGB agent named Alexander Litvinenko became extremely sick after drinking tea with a former Russian agent. His hair fell out, the number of blood cells in his body declined, he had gastrointestinal problems such as nausea and vomiting, and then he eventually died. It was later determined he was poisoned by a Group 6A element called polonium (but more on Litvinenko later).

Polonium is one of five elements that belong to the chalcogens, or Group 6A elements, which include oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). Depending on where you're looking, this group can also be called Group 16 or Group VIA - all mean the same thing.

Elements are placed in groups, or the vertical columns on a periodic table, because they share certain properties. You may have noticed that oxygen is in the same group as polonium, and it would appear that a radioactive element that killed a former KGB agent would have very little in common with the air that keeps you alive, but they actually have a quite a few things in common.

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Chalcogen Elements: Individual Elements Within the Chalcogens

Though elements in the chalcogen group share chemical properties, these elements do have their differences.

Oxygen

Oxygen is one of the most important elements on Earth, as it is required by most organisms to sustain life. Oxygen can be found in different forms such as elemental oxygen (O), molecular oxygen (O2) and ozone (O3). All three forms of oxygen are made from oxygen atoms, but differences in how their atoms are arranged leads them to act differently from each other. Molecular oxygen is the second most abundant gas in the air and makes up 21% of the atmosphere. Ozone in the upper layer of the atmosphere, and shields life from harmful ultraviolet rays from the sun.

Oxygen is extremely reactive and will chemically bond with many elements on the periodic table. One of the most important compounds, water (H2 O), is formed from oxygen and hydrogen atoms. Oxygen's ability to form compounds with many elements makes it ubiquitous: about 47% of the Earth's crust for example, is made up of mineral ores such as nitrates (nitrogen and oxygen), sulfates (sulfur and oxygen) and silicates (silicon and oxygen). In fact, silicon dioxide (SiO2) is the compound that forms the sand found on beaches.

Oxygen is found in the atmosphere as both molecular oxygen and ozone. It is also found in the compound water.

Oxygen in water and atmosphere

Not only is oxygen found abundantly in nature, it also has many commercial uses. Due to its ability to form heat and light when burned with other elements, also known as combustion, oxygen is used to produce energy. For example, NASA uses this energy to lift rockets into space. In order to do this, engineers use a fuel and react it with an oxidizer (oxygen). During combustion, the fuel reacts very quickly with the oxidizer and creates heat or energy that can be used by the spacecraft.

Though oxygen is found all over the Earth, humans cannot see, taste, or smell it. At room temperature, the gas is colorless, tasteless, and odorless. However, at lower temperatures, oxygen will condense and can be found as a light blue liquid.

Sulfur

Sulfur is the 17th most abundant element found on the planet's surface. Just like oxygen, sulfur forms bonds with many metals to form ores including stibite (Sb2 S3), pyrite (FeS), and cinnabar (HgS). One of the most important sulfur compounds is sulfuric acid, which is made with sulfur, hydrogen, and oxygen (H2 SO4). Sulfuric acid has many commercial uses including removing rust, and adding pigment to paints and dyes. Furthermore, sulfuric acid is mixed with phosphate rock to produce phosphates for fertilizers, which helps provide plants with necessary nutrients.

Though sulfur can be found in some macromolecules that humans require, many sulfur compounds are actually harmful to the body. For example, sulfur is found in many military weapons including mustard gas and nerve agents. It is also combined with charcoal and potassium nitrate to produce gunpowder.

Elemental sulfur is odorless, but when bonded to form other compounds, it can be extremely pungent. In fact, hydrogen sulfide smells just like rotten eggs, and is produced when bacteria decompose living matter. Because of its odor, sulfur is actually added to natural gas so that gas leaks can be more easily detected.

Unlike oxygen, sulfur is solid and yellow. It can be fond in different forms such as a powder or a crystalline. It is also brittle, a characteristic common in most non-metals, and will shatter when struck with a heavy object.

This sample of sulfur shows its yellow color and brittleness.

Sulfur sample

Selenium

The third chalcogen is the element selenium. Selenium can also form ores in the Earth's crust, but not nearly as much as oxygen and sulfur. Selenium is also not as prevalent as oxygen and sulfur, being the 67th most abundant element on the planet's surface. Though not as common as the previously discussed chalcogens, selenium still has many important uses. As a metalloid, it can conduct electricity and heat, especially when light is present. Therefore, selenium is used in solar cells, photocopiers, and cameras.

Found naturally in the ground, humans often ingest selenium when they eat plants and animals. This helps to meet the small (but necessary) dietary requirement of selenium. If there is too little dietary selenium, issues with reproduction, thyroid function, and DNA production can occur. Furthermore, studies have shown that people with little selenium in their diets have a higher chance of certain cancers and heart disease. On the other hand, those who ingest too much selenium can actually damage their teeth, hair, and nails.

Just like oxygen and sulfur, selenium can exist in different forms. It can exist as a shiny metal, or a red powder. Due to its interesting red color, selenium is sometimes used as a pigment in ceramics and paints.

Depending on the form, selenium can be metallic or red.

Selenium

Tellurium

Tellurium is found only in small amounts in the Earth's crust, and is the 72nd most abundant element on the Earth's surface. Like the previously described chalcogens, it can form ores like krennerite (AuTe2), sylvanite (AgAuTe2), and petzite (Ag3 AuTe2). Commercially, tellurium is used in the production of stainless steel to help increase the machinability, or allow it to be cut more easily. Tellurium can also be added to lead to improve its strength and decrease the risk of acid corrosion, or used to pigment ceramics and glass. Biologically, tellurium has no use and is considered toxic.

Tellurium is a metalloid just like selenium. The element can have a shiny luster but can also be found as a gray powder. Its ability to conduct heat and electricity allows it to also be used in solar cells.

A small amount of tellurium found inside quartz.

Tellurium

Polonium

Polonium is radioactive, which means its atoms are unstable and start to decay by releasing radiation energy. This instability is why polonium is one of the least commonly found elements on the periodic table. Scientists have discovered that polonium can be found inside uranium ore, but only in very little amounts.

Properties the Chalcogens Share

So, what do polonium and oxygen have in common? Oxygen, polonium, and the rest of the chalcogens all have six valence electrons; these are the outermost electrons, farthest away from the center of the atom. They give elements certain properties and help determine who the element can bond (or attach) with.

Most members of this group gain two electrons from another element so they can have eight valence electrons. Atoms are stable when they have eight valence electrons, so by gaining two, the chalcogens become stable. Electrons have a negative charge, and because most of the chalcogens gain two electrons, they get a -2 charge. This can also be referred to as a -2 oxidation state. An atom with a negative charge is called an anion.

So, the -2 oxidation state is the most common, but some of the other chalcogens can have other oxidation states. Sulfur, for example, can have oxidation states of +4 and +6. This means that sulfur can lose electrons and become more positive. Atoms that have a positive charge are called cations. And just to confuse you more, selenium, tellurium, and polonium can have oxidation states of +6! Because oxidation states can vary, just remember that -2 is the most common oxidation state for the chalcogens!

As you go down the group, the elements become more metallic. Oxygen and sulfur are nonmetals, selenium can be classified as a nonmetal or a metalloid, tellurium is a metalloid, and polonium is a metal. Nonmetals, metalloids, and metals all have different properties. For example, metals are good conductors of heat and electricity and are malleable (or bendy), whereas nonmetals tend to be poor conductors and are brittle. Metalloids have properties of metals and nonmetals.

Individual Elements Within the Chalcogens

Take a deep breath! That was a lot of information! And as you take a deep breath, imagine oxygen entering your mouth, traveling to your lungs, and then diffusing into your bloodstream, nourishing your cells, which leads us to our first chalcogen: oxygen. Not only is oxygen vital to your survival, but oxygen is everywhere! By mass, it makes up almost half of the Earth's crust and 90% of water. It makes up almost 21% of the Earth's atmosphere and it is the third most abundant element in the universe! But there's more! Almost 67% of your mass is oxygen. Wow!

So now we know oxygen is everywhere and is pretty important for your survival, but what else is there to know about this element? Well, you probably know that it is a colorless gas at room temperature and it is tasteless and odorless, but did you know that it is used in the refining of petroleum products, in steel and iron manufacturing, and as an ingredient in rocket fuel?

Another element you might already be familiar with from the chalcogens is sulfur. Have you ever been to a hot springs and noticed an unpleasant odor? You can thank sulfur for that! At room temperature, sulfur is a brittle, yellow solid that is odorless and tasteless, but when you combine it with hydrogen and form hydrogen sulfide you get that rotten-egg smell you may have smelled at a hot spring.

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Video Transcript

Chalcogens

Although what I am about to tell you sounds like a story out of a movie, it really happened. In November 2006, a former KGB agent named Alexander Litvinenko became extremely sick after drinking tea with a former Russian agent. His hair fell out, the number of blood cells in his body declined, he had gastrointestinal problems such as nausea and vomiting, and then he eventually died. It was later determined he was poisoned by a Group 6A element called polonium (but more on Litvinenko later).

Polonium is one of five elements that belong to the chalcogens, or Group 6A elements, which include oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). Depending on where you're looking, this group can also be called Group 16 or Group VIA - all mean the same thing.

Elements are placed in groups, or the vertical columns on a periodic table, because they share certain properties. You may have noticed that oxygen is in the same group as polonium, and it would appear that a radioactive element that killed a former KGB agent would have very little in common with the air that keeps you alive, but they actually have a quite a few things in common.

Properties the Chalcogens Share

So, what do polonium and oxygen have in common? Oxygen, polonium, and the rest of the chalcogens all have six valence electrons; these are the outermost electrons, farthest away from the center of the atom. They give elements certain properties and help determine who the element can bond (or attach) with.

Most members of this group gain two electrons from another element so they can have eight valence electrons. Atoms are stable when they have eight valence electrons, so by gaining two, the chalcogens become stable. Electrons have a negative charge, and because most of the chalcogens gain two electrons, they get a -2 charge. This can also be referred to as a -2 oxidation state. An atom with a negative charge is called an anion.

So, the -2 oxidation state is the most common, but some of the other chalcogens can have other oxidation states. Sulfur, for example, can have oxidation states of +4 and +6. This means that sulfur can lose electrons and become more positive. Atoms that have a positive charge are called cations. And just to confuse you more, selenium, tellurium, and polonium can have oxidation states of +6! Because oxidation states can vary, just remember that -2 is the most common oxidation state for the chalcogens!

As you go down the group, the elements become more metallic. Oxygen and sulfur are nonmetals, selenium can be classified as a nonmetal or a metalloid, tellurium is a metalloid, and polonium is a metal. Nonmetals, metalloids, and metals all have different properties. For example, metals are good conductors of heat and electricity and are malleable (or bendy), whereas nonmetals tend to be poor conductors and are brittle. Metalloids have properties of metals and nonmetals.

Individual Elements Within the Chalcogens

Take a deep breath! That was a lot of information! And as you take a deep breath, imagine oxygen entering your mouth, traveling to your lungs, and then diffusing into your bloodstream, nourishing your cells, which leads us to our first chalcogen: oxygen. Not only is oxygen vital to your survival, but oxygen is everywhere! By mass, it makes up almost half of the Earth's crust and 90% of water. It makes up almost 21% of the Earth's atmosphere and it is the third most abundant element in the universe! But there's more! Almost 67% of your mass is oxygen. Wow!

So now we know oxygen is everywhere and is pretty important for your survival, but what else is there to know about this element? Well, you probably know that it is a colorless gas at room temperature and it is tasteless and odorless, but did you know that it is used in the refining of petroleum products, in steel and iron manufacturing, and as an ingredient in rocket fuel?

Another element you might already be familiar with from the chalcogens is sulfur. Have you ever been to a hot springs and noticed an unpleasant odor? You can thank sulfur for that! At room temperature, sulfur is a brittle, yellow solid that is odorless and tasteless, but when you combine it with hydrogen and form hydrogen sulfide you get that rotten-egg smell you may have smelled at a hot spring.

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Frequently Asked Questions

Is group 6A the same as group 16?

Yes. Modern versions of the periodic table label the columns from 1 to 18. However, older tables did not label the transition metals and just numbered the tallest columns from 1 to 8. Therefore, group 6a and Group 16 both refer to the same column.

Why are group 6 elements called chalcogens?

Group 6a elements are called chalcogens because some of the elements can form ores, or rocks that contain metals, with other elements. The word "chalc" comes from the Greek word "ore" while "gen" means "formation".

What elements are in the chalcogen family?

Groups or columns on the periodic table are also known as families. The chalcogen family contains the elements oxygen, sulfur, selenium, tellurium, polonium and livermorium.

What are characteristics of the chalcogens?

All chalcogens found in nature can form ores with other elements. The only exception is livermorium, which is synthetically created. The chalcogens are composed of nonmetals, metalloids, and metals, so each element will display slightly different characteristics because of this. The first three elements in the group are needed for human function, while the last three elements are toxic.

What is the charge of group 6A on the periodic table?

The charge of Group 6a is usually -2, since all of the elements in this column have 6 valance electrons. In order to become stable, the elements can gain 2 negatively charged electrons and will therefore have a -2 charge.

Where are the chalcogens on the periodic table?

The chalcogens are found in the 16th column from the left of the periodic table. The first element in the column is oxygen.

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