Man has been exposed to changing surroundings ever since he came into existence. He has been quite interested in learning about his surroundings and studying and explaining the things that are happening around him. He has conducted experiments and observations to gather information as a result of his interest. Through the decades, it has also been in charge of many people’s research endeavors around the globe. Science is the name given to this knowledge. Due to its vast expansion and variety of subjects, science has been further divided into many branches. One of the most significant fields of science is chemistry. Chemistry can be summed up as the area of science that studies matter, including its properties, composition, and the changes that occur to it as a result of various activities.
What is Chemistry?
Chemistry is a sub-discipline of science that deals with matter’s properties, composition, and structure of elements and compounds.
What is Matter?
Matter is anything that occupies space and has mass. Everything we see around is matter. All the buildings, the bridges, the atomic particles are all matter. Even our DNA, the air, the molecules inside our bodies, everything is matter.
Classification of matter based on the physical state
The classification of matter based on their physical states involves the following states:
Solid state: The solid-state of matter has a definite shape and volume due to its closely packed particles. Solids are generally substances with particles that are moderately near one another. These particles are kept intact by solid intermolecular powers. Examples are rocks, ice, wood, etc…
Liquid state: Liquid particles have more space among them than solid particles, these particles are capable of free movement. Liquids, unlike solids, don’t have a definite shape, but they do have a definite volume. They can alter their shape and take the volume of the container in which they are kept. Examples are water, oil, petrol, etc…
Gaseous state: This phase of the matter doesn’t have any fixed shape or volume. Gases are highly compressible, and their diffusion rate is quite higher than both solids and liquids. The gas molecules have a huge amount of space between them. They are capable of free movement and can move around at random. Examples: carbon dioxide, air, etc.
To understand the physical nature of matter, let us take a solid substance like paper and start cutting it again and again. At some point in time, the paper cannot be cut into smaller pieces. This piece of paper is the smallest particle of paper as of now. But if we observe the paper pieces further we notice that the paper is made up of even smaller particles that are known as atoms. Atoms are the smallest units of any matter. Atoms can be divided into smaller particles that are known as Electrons, Protons, and Neutrons.
Classification of matter based on the chemical composition
Broad classification of matter in chemistry includes dividing them into:
Pure Substances
Impure Substance
Pure substances: These substances are made of similar atoms or molecules in a defined ratio. Therefore, they have a homogeneous chemical composition. Pure substances have a fixed structure and definite melting and boiling points. This classification of matter: i.e. the pure substances, can be further classified into two types.
Elements
Compounds
Elements:- Elements are defined as pure substances that contain a single type of atom or molecule. They can’t be broken down further by any physical or chemical means. At present, there are about 118 elements, out of which only a few are commonly found around us. Examples of elements are silver (Ag), gold (Au), sulfur (S), hydrogen (H), etc.
Compounds:-A compound is formed when more than one element combines chemically in a fixed ratio. Pure compounds can be chemically disintegrated or transformed into newer substances. Examples of these substances are salt (NaCl), carbon dioxide (CO₂), water (H₂O), etc.
Impure substances: They are made of different types of atoms or molecules. Unlike pure substances, their structure isn’t fixed or constant. Impure substances can be segregated into pure forms with the help of purification methods like sublimation, filtration, crystallization, etc. This classification of matter can be further subdivided into two categories based on their composition:
Homogeneous Mixture.
Heterogeneous Mixture.
Homogeneous mixture: Homogeneous mixtures have the same composition throughout their volume. You can’t see the individual particles in a homogeneous mixture. The amount of substances present in every sample of a homogeneous mixture is always the same. Examples of homogeneous mixtures are oil, wine, saline water, etc.
Heterogeneous mixture: A heterogeneous mixture, on the contrary, has varied compositions throughout its volume. Unlike homogeneous mixtures, these mixtures don’t blend perfectly. Therefore, you can determine what substances these mixtures are composed of. Examples of heterogeneous mixtures include mud water, concrete, chocolate chip cookies, etc.”