How Do Molecules of Elements Differ from Compounds?
All living things in this world are made up of Atoms. An atom is nothing but the smallest unit that forms a chemical element. Every other thing that is solid, liquid, and gas is composed of atoms. Atoms consist of protons, neutrons, and electrons that are present inside the nucleus of an atom. But what happens when two or more atoms meet? They form molecules. Molecules are formed when two or more atoms are joined together by chemical bonds. It is not that easy to understand the properties and structure of both atoms and molecules, but once understood the concept of it, it’s an interesting thing to learn.
Molecule of Element
When two more atoms are joined together by chemical bonds, a molecule is formed. As we may have learned from Dalton's atomic theory, all matter is made up of atoms, whether it can be elements. Elements are nothing but chemical substances composed of the same number of atoms. When two or more elements meet, a compound is formed. To find out the relation between molecules and elements, we need to study further.
What are Molecules of Elements?
Elements are formed when the same types of atoms are formed. The ratio of the number of atoms forming a molecule is the same. The properties of elements are determined by their structure. Elements can be formed by single or more atoms. For instance, we can take oxygen, as oxygen has 2 atoms (O2). Atoms are not drawn to scale. When these elements are joined together, a compound is formed. In this case, we can take H2O. Water has two hydrogens and one oxygen atom. Likewise, larger chemical compounds like methane (CH4). From these, we can learn how a group of atoms with nucleus can form elements and compounds with different properties and structures.
List of Molecule of Element
Elements can be monatomic, diatomic, triatomic, and polyatomic. Monatomic means elements made of one atom, diatomic refers to elements of two atoms, triatomic refers to elements made of three atoms, and polyatomic means elements made of more atoms. Some of the best ways we can learn about the list of elements are by going through the chemical structure of molecules.
Example of Molecule
All the elements of the periodic table are molecules. They are differentiated based on the number of atoms combined. Their structure also varies, along with their respective types. For example, when two identical atoms are formed, like O2, they compose homonuclear diatomic molecules (as atoms contain nuclei of positive charge, surrounded by electrons of negative charge).
Likewise, in carbon monoxide molecules (CO2), there are two different atoms and hence they compose heteronuclear diatomic molecules. As atoms consist of a single positively charged nucleus, surrounded by negatively charged electrons, during the chemical bonding, the electrons interact with each other along with the nuclei, causing a surge of energy between them and when this energy is lowered, a molecular compound or element is formed. Molecules do not break easily due to the electron pairs or covalent bonds holding them together.
Difference Between Atoms and Molecules
Interesting Facts
Atoms are mostly empty space.
There are over 100 different kinds of atoms.
The same elements occur everywhere in the universe.
Astatine is the rarest element on Earth.
Key Features
Molecules are formed when two or more atoms are combined together.
All matter is made up of atoms, even elements.
When two or more elements meet, they form compounds.
An atom has a nucleus at the centre and electrons surrounding it.
FAQs on Molecules of Elements: Definitions, Types & Properties
1. What is a molecule of an element?
A molecule of an element is the smallest particle of an element that can exist independently and show all the properties of that element. It is formed when two or more atoms of the same element are chemically bonded together. For instance, an oxygen molecule (O₂) consists of two oxygen atoms bonded together.
2. What is meant by the 'atomicity' of an element?
Atomicity refers to the total number of atoms present in one molecule of an element, compound, or substance. For example, the atomicity of an oxygen molecule (O₂) is 2 because it contains two atoms, while the atomicity of an ozone molecule (O₃) is 3. Elements with an atomicity of one, like Helium (He), are called monoatomic.
3. Can you provide examples of molecules of elements based on their atomicity?
Yes, molecules of elements are classified based on their atomicity. Here are some examples:
- Monoatomic Molecules (1 atom): Most noble gases like Helium (He), Neon (Ne), and Argon (Ar).
- Diatomic Molecules (2 atoms): Hydrogen (H₂), Nitrogen (N₂), Oxygen (O₂), and Chlorine (Cl₂).
- Polyatomic Molecules (more than 2 atoms): Ozone (O₃), Phosphorus (P₄), and Sulphur (S₈).
4. How is a molecule of an element different from a molecule of a compound?
The key difference lies in the types of atoms involved. A molecule of an element consists of atoms of only one type (e.g., O₂, N₂, S₈). In contrast, a molecule of a compound consists of atoms of two or more different elements chemically combined in a fixed ratio (e.g., Water - H₂O, Carbon Dioxide - CO₂).
5. Why do some elements like Helium (He) and Argon (Ar) exist as single atoms instead of forming molecules?
Elements like Helium and Argon are called noble gases. They have a completely filled outermost electron shell, which makes them exceptionally stable and chemically inert. Because they are already in a stable state, they do not have the tendency to gain, lose, or share electrons to form chemical bonds with other atoms. Therefore, they exist as individual, stable atoms (monoatomic molecules) rather than forming multi-atom molecules.
6. Which common elements are known to exist as diatomic molecules?
There are seven common elements that naturally exist as diatomic molecules under standard conditions. These are: Hydrogen (H₂), Nitrogen (N₂), Oxygen (O₂), Fluorine (F₂), Chlorine (Cl₂), Bromine (Br₂), and Iodine (I₂). These elements are highly reactive as single atoms and achieve stability by sharing electrons to form a two-atom molecule.
7. Can a molecule of an element have different properties from a single atom of that element?
Yes, absolutely. The arrangement and number of atoms in a molecule can drastically change its properties. A classic example is the element oxygen. The oxygen molecule (O₂) is a stable, diatomic gas essential for respiration. However, the ozone molecule (O₃), also made only of oxygen atoms, is a triatomic molecule that is a toxic pollutant at ground level but protective in the Earth's upper atmosphere. This shows how molecular structure dictates chemical and physical properties.
8. How is the chemical formula for a molecule of an element written?
The chemical formula for a molecule of an element is written using the symbol of that element followed by a subscript number indicating its atomicity. For example, if a molecule of phosphorus contains four atoms, its formula is written as P₄. If an element is monoatomic, like Argon, its formula is simply its symbol, Ar.
