Properties of Metalloids and Noble Gases

An element is a material that we cannot break down into other substances. In other words, it is the most basic form of matter. Metals, metalloids, and non-metals are three types of elements. 

Metals occupy the majority of the periodic table. Non-metals are found on the top-right side of the periodic table. Noble gases are examples of non-metals. 

Metalloids are elements that have characteristics of both metals and non-metals. They occupy the space between metals and non-metals in the periodic table.

What are Metalloids?

Metalloids are chemical elements with properties of metals as well as non-metals. Alternatively, we can describe them as a mixture of metals and non-metals. Although there is no standard definition for metalloids, the term is still widely used in Chemistry.

There are six well-known metalloids: Antimony, Tellurium, Boron, Germanium, Arsenic, and Silicon. Additionally, five more elements are not classified as metalloids as frequently as the ones mentioned before. They are Selenium, Astatine, Polonium, Aluminium, and Carbon.

In the traditional periodic table, all 11 metalloids lie in the diagonal region of a p-block, extending from Boron in the upper left corner to Astatine in the lower-left corner. Certain periodic tables contain a line that divides metals and non-metals. In such tables, we can locate the metalloids near this line.

We use metalloids in biochemical agents, alloys and catalysts, flame retardant glasses, optical storage and electronics. They also have applications in pyrotechnics, electronics and semiconductors.

Properties of Metalloids

Let us look at the physical and chemical properties of metalloids.

Physical Properties of Metalloids

• Metalloids are like metals. However, they are brittle, like non-metals.

• They form solids at room temperature.

• They show good conductivity at room temperature.

Chemical Properties of Metalloids

• We can use them to make alloys with metals.

• Their non-metallic or metallic behaviour during reactions is dependent on the substance with which they react.

• Metalloids possess chemical and physical properties that are similar to the properties of metals as well as non-metals.

What are Noble Gases?

Noble gases are inert, non-reactive gases found in trace concentrations in the atmosphere. Xenon, Krypton, Argon and Neon are examples of noble gases.

All noble gases are present in the atmosphere, and we can also produce them artificially. Freezing natural gas forms Helium. Radon is a radioactive noble gas created by a radioactive reaction of heavy elements like Thorium, Radium, and Uranium.  

Properties of Noble Gases

Here are the physical and chemical properties of noble gases.

Physical Properties of Noble Gases

Below are the main physical characteristics of noble gases.

Atomic Radii (atomic size)

As we progress lower in the group from Helium to Radon, the atomic size of noble gases keeps on increasing. It happens because the amount of occupied shells containing valence electrons grows as we move downwards in the table.

Boiling and Melting Points

• All elements from group 18 are present in a gaseous state at room temperature and pressure.

• The boiling and melting points of all noble gases are very low because:

  • They are composed of mono-atomic molecules, joined by small Van Der Waal forces of attraction.

  • Just a small degree of heating is necessary to resist weak interatomic forces.

• As we move lower in the group, the melting and boiling points of noble gases increase due to the following reasons:

  • In the lower section of the table, the radius of the atoms increases. It causes the formation of stronger Van Der Waal forces of attraction between atoms.

  • More energy is necessary to counteract the forces of attraction between interatomic particles in the process of melting or boiling.

Density

All elements in group 18 have low densities. The density grows as the mass continues to increase.

Ionisation Energy

The ionisation energy continues to decrease. Noble gases have the highest Ionisation Enthalpy of all the groups in the periodic table. It indicates that they are chemically inert.

Ionisation Potential

The radius of the atoms increases as we move down the table. Consequently, it increases the forces of attraction and ultimately causes an increase in the polarity while causing a decrease in the ionisation potential. 

It is because the valence electrons in larger atoms within the group are not held together tightly by the atom as they are present far from the nucleus.

Electrical and Heat Conductivity

Except for neon, all noble gases conduct electricity. However, inert gases from group 18 are bad conductors of heat. 

Chemical Properties of Noble Gases

• They are not flammable, are odourless, colourless and have low chemical reactivity.

• All noble gases conduct electricity and fluorescence that is needed in various situations to provide an environment that is safe and constant.

• They are insoluble in water.

• As they have an entire octet, it makes them extremely stable. Therefore, noble gases are not likely to mix with elements and form chemical bonds due to their inability to make or take electrons. But, there are a few exceptions, like Xenon.  

Conclusion

Metalloids are compounds that exhibit the properties of non-metals and metals. Many are also semiconductors. It means that many of them can conduct electricity in some instances.  

Inert gases and aerogens are other names of noble gases. They are elements in group 18 in the modern periodic table. All noble gases exist in normal pressure and temperature conditions in a gaseous state.