Molecular Nature Of Matter

Introduction

Our universe is composed entirely of matter, which serves as the fundamental building block. Matter can be defined as a substance that occupies space in the form of volume and has mass as well. Solids, liquids, and gasses are some of the states in which matter can exist. It only comprises particles with mass; thus, massless particles, such as photons, do not fall within this group. Let’s take the case of water that can exist in all three states as liquid water in liquid form, steam in gaseous form, and ice in solid form. The matter has a molecular nature. It is made up of atoms, which are tiny particles. 

According to the Atomic hypothesis, all objects are made up of small fundamental units called atoms, which can be characterized as tiny particles that move in perpetual motion and attract or repel each other based on their inter-particle distance. According to Dalton’s conclusions, an atom is the smallest unit of matter that can’t be further divided.

We will look at the definition of the molecular nature of matter physics and understand the concept in detail.

Dalton’s Theory

Dalton’s atomic theory is with what we will begin, as it’s the very first of its kind. John Dalton had first introduced the atomic theory of matter; however, the origin is not well understood. He stated a set of laws or postulates that describe the behavior of particles in matter. Dalton’s theory was considered concrete until even smaller particles like protons and neutrons were discovered. Finally, Dalton proposed that all matter, whether it’s a compound, a molecule, or a mixture, is made up of smaller particles known as atoms, and they can not be separated any further. 

Dalton theory states that:

• The tiny particles called Atoms are what the universe is made up of. 
• Atoms are indivisible particles since they cannot be generated or destroyed during a chemical reaction.
• Every atom of an element has similar mass and chemical characteristics.
• Atoms of different elements have distinct mass and chemical characteristics.
• The atoms in a compound are combined in the ratio of tiny whole numbers. 
• For a given element, the atoms and the relative number are constant.   
• The tiny particles called Atoms move around in a perpetual order attracting each other when they are a little distance apart. They rebel when forced very close to each other. 

Now, let us study Avogadro’s law about the molecular nature of matter and change.

Avagadro’s Law

As per Avagadro’s law, the number of gasses has an equal number of molecules when there is a similar volume at equal pressure and temperature. Also, the law states that if the pressure and temperature are constant for an ideal gas, its volume and amount are directly proportional to each other. Basically, Avagadro’s law is based on gasses that relate to the volume and the total amount present. 

According to Avagadro law, 

V ∝ n 

Here, V stands for volume of the gas and n stands for the number of moles of the gas.

Avagadro’s constant is k in case of V = kn

When all the collisions between atoms and molecules are elastic, and there is no attractive intermolecular force it is defined as ideal gas. In such a scenario all the internal energy is in the form of kinetic energy and when there is any increase in internal energy the temperature changes. Absolute pressure (P), absolute temperature (T) and volume (V) are the characteristics of an ideal gas.

Thereby the law of Avagadro is related to the idea

Next, let us look at Gay Lussac’s findings on the chemistry molecular nature of matter and change.

Gay Lussac’s Law

As per Gay Lussac’s law, when the volume of a gas is taken as constant, then the pressure of a given amount of gas varies directly to its temperature. That’s why this law is also called the “Pressure law” as per its theory when the volume is constant, pressure is directly proportional to temperature. He has also given substantial evidence of the relationship between pressure and temperature of fixed gases and has been the first one to do so.

The Current Molecular Nature Of Matter Physics

These hypotheses were popular until the late 19th century when several scientists pointed out faults in Dalton’s atomic hypothesis. One of the fundamental rules of physics states that matter is made up of small particles known as atoms. As we learned more about atoms, we realized that they are made up of even smaller particles known as protons, neutrons, and electrons. It can be diagnosed in various proportions in an atom. However, technology helps discover that atoms consist of electrons and a nucleus that contains both protons and neutrons. Inside neutrons and protons, even smaller particles exist called quarks. 

Key Take-Aways – Molecular Nature Of Matter

• Molecules that are made up of one or more atoms constitute matter.
• In solids, the atoms and molecules are fixed, and the space between them is of a few angstroms, and so they cannot move.
• Against solids in the case of liquids, the atoms are not as rigidly fixed as in solids and can thereby move, which enables a liquid to flow.
• In gasses, atoms can freely travel without colliding for large distances. The term “Mean Free Path” is the average distance a molecule can travel without colliding, and it’s of the order of thousands of angstroms.
• The closeness in the case of solids and liquids makes the interatomic force important, which is kind of neglected in the instances of gasses.