Matter, in its various forms, surrounds us every day, from the air we breathe to the food we eat. But have you ever wondered how matter is classified?
To begin our journey, let’s first understand what matter is. Matter is anything that occupies space and has mass. It can be solid, liquid, or gas.
Now, let’s dive into the classification of matter. The “classification” of matter doesn’t refer to the three “states” of matter which you have learnt previously. Classification of matter is based on their compositions.
There are 2 types of matter. Pure and Impure substances. Within pure substances, there are elements and compounds. Whereas in impure substances there are homogenous mixtures and heterogeneous mixtures. Pure substances are substances that have a definite and constant composition. They are made up of only one type of particle, either atoms or molecules, and cannot be separated into simpler substances by physical or mechanical means.
Elements: Elements are pure substances that consist of atoms from only one element. They cannot be broken down into simpler substances by ordinary chemical reactions. Elements are represented by symbols, usually one or two letters. Such as: Gold (Au), or Oxygen (O), or Carbon (C), or Hydrogen (H).
Compounds: Compounds are pure substances composed of two or more elements chemically combined in fixed proportions. The atoms of different elements are bonded together to form molecules of the compound. Compounds can only be separated into their constituent elements through chemical reactions.
Shown on the left in “Figure 1.2” is a picture of what elements and compounds can look like. For example, an element could be pure gold, 24 carat gold. Whereas a compound would be jewelry, which is made up of gold and copper, essentially an alloy. A compound is a substance made up of different elements chemically combined in fixed proportions. Such as Water (H2O) or table salt (NaCl).
Interestingly compounds have unique chemical properties that set them apart from the elements they are made of. Whereas elements have distinctive and definite properties that only stand true in elemental state.
Above is “Figure 1.3” which provides a visual understanding of the differences between elements (atoms and molecules), compounds and mixtures. Now, as we move on to Impure substances, or also known “mixtures” we see two types. Homogenous and Heterogenous. Unlike pure substances, mixtures are made of two or more different particles (either atoms or molecules) and can be separated by physical means, such as filtration or evaporation. Homogeneous Mixtures: Homogeneous mixtures, also called solutions, are uniform throughout. In a homogeneous mixture, the particles of different substances are evenly distributed and not easily distinguishable. These mixtures have the same composition and properties in all parts of the mixture. For example: Saltwater is a mixture of salt (sodium chloride) dissolved in water. It appears as a clear liquid because the salt particles are evenly dispersed. To add on, air in the atmosphere is a homogenous mixture of gases like nitrogen, oxygen, carbon dioxide, argon and more but it again appears as a substance despite being a homogeneous mixture because its composition is uniform throughout.
Heterogenous mixtures: Heterogeneous mixtures are not uniform throughout and have visibly different components. The particles of different substances in a heterogeneous mixture are not evenly distributed and can be distinguished from one another. These mixtures have varying compositions and properties in different parts of the mixture.
For example: soil is a heterogeneous mixture as it composes of sand, silt, clay, organic matter, and rocks which can all be distinguished using the naked eye. The different particles in soil are not evenly distributed and can be observed as distinct layers or clumps.
Some mixtures may appear more uniform and closely resemble homogenous mixtures, while others may be highly variable and clearly exhibit heterogeneity. This means that mixtures can have different levels of heterogeneity, with some being closer to uniform (homogenous) and others being less uniform.
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