Similarities Between Atom and Molecule

What is an Atom?

An atom is the smallest unit of an element that can participate in a chemical change without being recreated or destroyed in the process. Instead, atoms are re-arranged to form a different substance or substances different from their original form before the onset of the chemical change or reaction and they show the same properties of that element which they represent.

In the center of an atom lies the nucleus which is made up of three subatomic particles (tinier than atoms) namely, protons which are positively charged, neutrons which have no charge (neutral), and are surrounded in a much larger volume by electrons– negatively charged. 

When it comes to the mass of an atom, it is important to highlight that the majority of its mass is contained in the nucleus. This is because the protons and neutrons which are attached to the nucleus are much heavier than the surrounding electrons. Although, there may be a situation where the number of protons and the number of electrons particles are equal and in such a state, the atom is said to be a neutral atom whereas if the number of its subatomic particle are not equal, then the atom is electrically charged and is known as an ion.

Particles of atoms can be of different types or the same type. When they are made up of the same type of atom, they are known as an element. Also, atoms of one element are different from atoms of another element. For instance, in the element called potassium represented with the symbol (K), you will only have the same type of atom. However, an atom of one element can be converted into an atom of another element through the fission of the nucleus.

Just as an element is formed from the coming together of atoms of the same type, a compound is formed when atoms of two or more elements of the same whole number ratio are chemically combined to form a bond. For instance, a combination of one atom of sodium (Na) and an atom of chlorine (Cl) elements produces a compound known as sodium chloride (NaCl) (with a whole number ratio of 1:1) or a combination of two hydrogen atoms and one oxygen atom will form a compound known as water (with a whole number ratio of 2:1).

 In other to describe a compound clearly, a molecular formula can be used as this would show the actual number of atoms of each element in a molecule of a compound.  However, it is important to highlight that compounds may have the same molecular formula but are structurally different.

What is a Molecule?

A molecule is a mixture of two or more atoms of an element held together by a chemical bond. For instance, when a hydrogen atom combines with an oxygen atom, they combine and form a molecule that we know as water, or when three oxygen atoms combine, they form an ozone molecule (O3). 

However, a molecular formula is used to indicate the type of atom and the number of each type of atom in a compound. This is also known as the molecule’s identity. In the research and health sector, a molecule’s identity can be used as a biomarker that could be used for disease diagnosis based on the number and identity of molecules present in a patient’s exhaled breath. Using this method as an early detection mechanism can allow for disease treatment before the condition becomes severe or irreversible.  

Also, molecules can change from one form to another through chemical reactions when the conditions are appropriate. In this case, the atoms rearrange themselves to form a different molecule. For instance, a water molecule in a solid phase (ice), under appropriate conditions can change to a liquid phase. 

Chemical reactions which involve molecules happen around us and within us as humans on a daily bases. For instance, in food digestion, complex carbohydrates are digested and broken down to glucose which the body uses as a source of energy. 

Molecules are the building block of both living and non-living things. They can be classified as,

• Organic and Inorganic molecules 

The organic molecules, also known as biomolecules (whose foundation is shaped by carbohydrate, lipid, protein, and nucleic acid molecules) consist of carbon, hydrogen, oxygen, and nitrogen atoms whereas the inorganic ones also contain carbon but are not linked to hydrogen. For example, diamond and salt.

• Polar and non-polar molecules

In polar molecules like water, the electron density is asymmetrically distributed in all directions as a result of the difference in electronegativity (net dipole moment) whereas, in non-polar molecules like oxygen, the electron density is symmetrically distributed in such a way that there is no net dipole moment.

Types of molecules

There are three types of molecules and they are; 

• Molecules of an atom. For example, Helium. It has only one atom.
• Molecule of an element. For example, an ozone molecule has three oxygen atoms.
• Molecule of a compound. It has a combination of atoms of different elements. For example, salt–sodium chloride (NaCl)

Similarities between atom and molecule

• In terms of size, an atom is the smallest unit of an element while a molecule is the smallest unit of a substance.
• When aggregated, an atom exhibits the same properties as the element it belongs to and the same goes for a molecule but in this case, it exhibits the properties of that substance.
• Atoms and molecules are neutral.
• Atoms and molecules can react with each other and also with other molecules and atoms.

Frequently Asked Questions

What is an atom and molecule with an example?

An atom is a tiny indivisible particle that can neither be created nor destroyed in any chemical reaction. They can only be transformed or rearranged to form a different substance. An example of an atom is hydrogen represented by the symbol (H).

What are the three types of an atom?

An atom is composed of three subatomic particles namely, Proton (Positive electric charge), Neutron (Neutral), and Electron (Negative charge).

What is an atom in real life?

In real life, everything around us is made up of matter (anything that occupies space). Matter itself is made up of tiny particles of atoms. For example, the water we drink contains one oxygen atom and two hydrogen atoms (H₂O).

Does the atom still exist?

Yes, atoms still exist because matter still exists all around us.

What are the three types of molecules?

The three types of molecules are; 

• Molecules of an atom. For example, Helium. It has only one atom.
• Molecule of an element. For example, a hydrogen molecule has two hydrogen atoms.
• Molecule of a compound. It has a combination of atoms of different elements. For example, salt–sodium chloride (NaCl).