Concept of elements, atoms and molecules

Elements, atoms and molecules are one of the most essential topics in chemistry that might confuse students sometimes. While these three things sound very similar, they have very different meanings in chemistry. In this article, we will discuss everything you need to know about elements, atoms and molecules. Let us now begin our discussion with understanding what an element is and then we will define atom and molecules.

Meaning of elements

Elements in chemistry are pure substances containing only those atoms with an equal number of protons in their nuclei. Every element has a unique number of protons, for instance, hydrogen has only one proton while carbon has six protons. A chemical element  is a substance that cannot be broken down by general chemical processes .As of now, there are 118 elements. Here are some examples of elements:

• Iron 
• Copper
• Krypton
• Neon
• Caesium

Let us know about various elements that you will find in a periodic table.

Types of elements:

The elements are divided into several groups of metallic and non-metallic elements in the periodic table. Metallic elements are again grouped into transition metal, f block metal and main group metal. 

There are various categories under metallic and non-metallic elements, which are again divided based on their Properties.

Some of the common elements are :

• Sodium
• Platinum
• Boron
• Carbon
• Hydrogen
• Lead
• Silicon

Meaning of atoms

Atoms are commonly known as the building blocks of matter.

They are the smallest unit of matter that retain chemical properties of elements. It is important to note here that atoms don’t exist independently, instead they form molecules and ions to form matter. It is a matter that we can see and touch. Atoms are not visible to the naked eye. They are very small and thus experiments are conducted on large quantities of atoms to know their behavior and structure. The results from these experiments can be used to build a hypothesis that could explain how the true atoms work.

The smallest particle of an element is known as the atom. Atoms cannot be created nor can they be destroyed. All the atoms of an element have similar chemical properties. 

There are 3 fundamental types of particles that atoms consist of, they are :

• Protons 
• Neutron
• Electron

Protons and neutrons have almost similar atomic masses. Compared to the atomic mass of protons and neutrons, electrons have almost negligible mass. The proton is positively charged, an electron is negatively charged and a neutron is neither positively nor negatively charged. Now, atoms have no charge because they contain an equal number of protons and neutrons. Its nucleus is positive because it contains protons and neutrons only. The nucleus is the center of an atom. Most of the atomic weight is present in the nucleus of the atom. 

Size of the atom:

The size of the atom is very small, smaller than what we can imagine. One layer of millions of atoms will be as thick as a sheet of paper. Thus it becomes almost impossible to calculate the size of one single atom. However, the size of the atom is calculated by assuming that the distance between two atoms is equal to half of the atomic radius. The radius of an atom is measured in nm or nanometers where 1 m = 109 nm.   

Now that you know what an atom is, let us move on and understand what a molecule is.

Meaning of molecule

Molecules are the smallest component of a compound and they have chemical properties very similar to that of compounds. A group of atoms constitutes molecules. Structurally an atom is divided into three: protons, neutrons and electrons. We have already studied that protons are positively charged, neutrons don’t charge and electrons are negatively charged.

Each element has what is called an atomic number which is equal to the number of protons in the nucleus of an atom. The atomic number is denoted by the alphabet ‘Z’.

When the atomic mass is calculated the mass of its elements is considered. Since the mass of the electron is almost negligible, the mass of the atom is generally composed of protons and neutrons. The mass number of an atom is generally denoted by the alphabet ‘A’. A molecule is the smallest particle of a compound with chemical and physical properties.

Now that we know the atoms and molecules definition, let us see some examples of molecules.

Some examples of molecules:

Every molecule is composed of two or more two atoms. Here are some of the most common examples of molecules:

Water – H2O

Nitrogen – N2

Ozone- O3

Calcium oxide – CaO

Glucose is a kind of sugar – C6H12O6

Table salt – NaCl

Forces between the atoms and molecules

A simple force between atoms and molecules occurs because of the transfer of electrons.

Examples of sodium fluoride will make everything clear.

Nuclear charge of sodium atom: +11, where two electrons are present in the K shell, eight electrons are present in the L shell and one electron is present in the M shell. The atom present in the outermost shell can be easily transferred to the fluoride atom. After the transfer, both the atoms consist of a complete shell. Now, sodium has a net charge equal to +1 whereas fluorine has a net charge equal to -1. Thus these ions attract each other by coulombic interaction. 

Conclusion

This was all that you needed to know about elements, atoms and molecules. Elements in chemistry are pure substances that contain only those atoms which have an equal number of protons in their nuclei. Atoms are commonly known as the building blocks of matter. They are the smallest unit of matter that have chemical elements properties. Finally, molecules are the smallest component of a compound and they have chemical properties very similar to that of compounds.