WHAT ARE DIATOMIC ELEMENTS? (EXAMPLES) - CHEMISTRY - 2024

The diatomic elements, homonuclear diatomic molecules also called, are composed of only two atoms of the same chemical elements. Some elements cannot exist by themselves, even when isolated from any other type of atom.

Elements of this nature will combine with atoms of the same element to be stable. In other words, hydrogen, a diatomic element, cannot be by itself. There cannot simply exist H.

Hydrogen is so reactive that when it is isolated from everything but hydrogen, it will combine into a diatomic (two-atom) molecule. Hence, hydrogen gas, which is sometimes used as fuel, exists as H ₂.

Diatomic molecules

Diatomic molecules contain two atoms that are chemically bonded. If the two atoms are identical, as for example, the oxygen molecule (O ₂), it makes up a homonuclear diatomic molecule, while if the atoms are different, as in the carbon monoxide (CO) molecule, it forms a diatomic molecule heteronuclear.

Molecules containing more than two atoms are called polyatomic molecules, for example, carbon dioxide (CO ₂) and water (H ₂ O). Polymer molecules can contain many thousands of component atoms.

There are seven elements that make up diatomic molecules. The following 5 element gases are found as diatomic molecules at room temperature and pressure:

-Hydrogen - H ₂

-Nitrogen - N ₂

-Oxygen - O ₂

-Fluoride - F ₂

-Chlorine - Cl ₂

Bromine and iodine commonly exist in liquid form, but also as diatomic gases at slightly higher temperatures, making a total of 7 diatomic elements.

-Bromo - Br ₂

-Iodine - I ₂

Diatomic elements are halogens (fluorine, chlorine, bromine, iodine) and elements with a -gen ending (hydrogen, oxygen, nitrogen). Astatin is another halogen, but its behavior is unknown.

Properties of diatomic elements

All diatomic molecules are linear, which is the simplest spatial arrangement of atoms.

It is convenient and common to represent a diatomic molecule as two point masses (the two atoms) connected by a massless spring.

The energies involved in the movements of the molecule can be divided into three categories:

• The translational energies (the molecule that moves from point A to point B)
• Rotational energies (the molecule rotating around its axis)
• Vibrational energies (molecules that vibrate in a variety of ways)

All diatomic elements are gases at room temperature with the exception of bromine and iodine which are liquid (iodine can even be in the solid state), and all with the exception of oxygen and nitrogen are linked by a single bond.

The oxygen molecule has its two atoms joined by a double bond and the nitrogen molecule by a triple bond.

Some diatomic elements

Hydrogen

Hydrogen (H ₂), with an atomic number of 1, is a colorless gas that was not formally discovered as an element by Henry Cavendish until 1766, but was accidentally found about a hundred years earlier by Robert Boyle.

Figure 1: structure of the hydrogen molecule.

It is a colorless, odorless, non-toxic gas that exists naturally in our Universe. Being the first element on the periodic table, hydrogen is the lightest and most abundant of all the chemical elements in the universe since it makes up 75% of its mass.

Nitrogen

Nitrogen (N ₂) has an atomic number of seven and makes up about 78.05% of Earth's atmosphere by volume.

It is an odorless, colorless, and mostly inert gas, and it remains colorless and odorless in a liquid state.

Figure 2: structure of the nitrogen molecule.

Oxygen

Oxygen (O ₂) has an atomic number of eight. This colorless, odorless gas has eight protons in its nucleus and is pale blue in its liquid and solid states.

One fifth of the Earth's atmosphere is made up of oxygen and it is the third most abundant element in the universe by mass.

Figure 3: structure of the oxygen molecule.

Oxygen is the most abundant element by mass in the Earth's biosphere. The high concentration of oxygen in the atmosphere is the result of the Earth's oxygen cycle, which is predominantly driven by photosynthesis in plants.

Fluorine

Fluorine (F ₂) has an atomic number of nine, and it is the most reactive and electronegative of all the elements. This non-metallic element is a pale yellow gas that is a member of the halogen group.

George Gore was apparently the first scientist to isolate fluorine, but his experiment exploded when the fluorine that was produced reacted with hydrogen.

Figure 4: structure of the fluorine molecule.

In 1906, Ferdinand Frederic Henri Moissan was awarded the Nobel Prize in Chemistry for his work on the isolation of fluorine in 1886. It is the most electronegative element on the periodic table.

Chlorine

Chlorine (Cl ₂) is a member of the halogen group with an atomic number of seventeen. One of its forms, NaCl, has been in use since ancient times.

Figure 5: structure of the chlorine molecule.

Chlorine has been in use for thousands of years in many other forms, but it was not named until 1810 by Sir Humphry Davy.

Chlorine in its pure form is yellowish green, but its common compounds are typically colorless.

Bromine

Bromine (Br ₂) has an atomic number of thirty-five. It is a heavy dark brown liquid, the only non-metallic element that is a liquid.

Figure 6: structure of the bromine molecule.

Bromine was discovered by Antoine J. Balard in 1826. It was used for important purposes long before it was formally discovered.

Iodine

Iodine (I ₂) has an atomic number of fifty-three, with fifty-three protons in the nucleus of an atom. It is a blue-black non-metal that plays a very important role in organic chemistry.

Figure 7: structure of the iodine molecule.

Iodine was discovered in 1811 by Barnard Courtois. He named it iodine from the Greek word "iodes" which means violet. It is a blue-black solid.

Iodine plays a very important role in the biology of all living organisms since its deficiency leads to diseases such as hyperthyroidism and hypothyroidism.

References

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