What is Classification of Matter?

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Classification of matter graph

Definition for Classification of Matter

The definition of classification of matter is categorizing materials according to their chemical and physical properties.

Under Classification of matter, chemists classify matter according to whether it is homogeneous or heterogeneous.

So let’s talk about the definition of Homogeneous and Heterogeneous mixtures.

Definition of Homogeneous

Homogeneous means of uniform composition throughout.

Homogeneous mixture Examples

  • Pure water
  • Sugar
  • Honey
  • Aluminum
  • Brass
  • A solution of salt in water
  • Petrol
  • Whiskey
  • Clean air

Definition of Heterogeneous

Heterogeneous means have non-uniform composition where we can recognize small pieces of the material that are different from other pieces.

Heterogeneous mixture Examples

  • Fruit cake
  • Strawberry jam
  • Concrete
  • Wood
  • Cork
  • Brick
  • Beer
  • Water with ice in it

Moreover, The heterogeneous matter may be separated by physical or mechanical means into homogeneous components, E.g., iron filing and sulfur, salt and sand, water, and Condy’s crystals.

Another way of Classification of matter is to divide it into mixture and pure substances.

Graph of Classification of Matter
Graph of Classification of Matter

What is a Pure Substance?

Pure substance is one which cannot be separated into two or more substances by physical means and which has constant properties throughout the whole sample, such as color, density, melting and boiling points, regardless of how it prepares or how many times it subjects to purification procedures.

A pure substance has constant chemical composition.

Examples of Pure Substance

  • Table salt
  • Sugar
  • Copper
  • Aluminum
  • Diamond
  • Gold
  • Polythene
  • Epsom salts
  • Alum
  • Alcohol

If a sample of matter is not a pure substance, then we call it a mixture.

Definition of Mixture

Mixture is a physical combination between two or more substances that are not chemically combined and mixed in the form of colloids, solutions, and suspensions.

Homogeneous and Heterogeneous mixtures
Homogeneous and Heterogeneous Mixtures

A sample of matter is a mixture if,

  1. It can separate into two or more pure substances by physical or mechanical means;
  2. It displays the properties of the pure substances making it up; and
  3. Its composition, i.e., relative amounts of each pure substance present, can be varied.

Examples of Mixtures

  • Seawater
  • Air
  • Coffee
  • Milk
  • Petrol
  • Whiskey
  • Brass
  • Silver coins

Let’s talk about impure substances.

What is an Impure Substance?

An impure substance is one substance contaminated with small amounts of other substances and is, therefore, a mixture.

According to the definition above, a sample of water containing pieces of ice is not a pure substance because some of the ice, such as density, are different from those of the water. Such a sample is, therefore, a mixture, and since its properties are not uniform throughout, because of that it is heterogeneous.

Heterogeneous substances are always mixtures (either of two or more pure substances or two or more physical forms of the one pure substance).

for example, A sealed tube containing liquid bromine vapor is similarly a heterogeneous mixture of two physical foams, liquid, and vapor.

Physical methods of separating components of mixtures

  1. Visual sorting or mechanical sieving;
  2. Dissolution of one component (with the other being insoluble in the chosen solvent), substance by evaporating the solution to dryness;
  3. Crystallization, used when two or more components are soluble in the chosen solvent at high temperature, but with one component having a sufficiently low solubility at low temperature for most of it to crystalize out;
  4. Distillation, where one component is boiled off and condensed back to liquid, as a result in obtaining pure water from seawater;
  5. Sublimation, which involves heating a mixture in which one component vaporizes and condenses back to a solid on a cool surface.

Pure substances fall into two categories, those which can be decomposed into two or more simpler pure substances, e.g., by heating, by the passage of an electric current or by what we call chemical reactions, and those which cannot. We call the latter elements and the former compounds.

Let’s talk about what are the elements and substances.

What is an Element?

According to the definition of an element, An element is a pure substance that cannot decompose into simpler substances.

Examples of Elements

  • Aluminum
  • Copper
  • Carbon (diamond)
  • Oxygen
  • Gold
  • Nitrogen and
  • Mercury

If you want a full informative article that covers the whole area of Elements, Check out one of the best articles about the Survey Of Elements.

so, let’s talk about another major subject in the classification of matter

What is a compound?

A compound is a pure substance that can decompose into simpler substances, e.g., Into elements.

Examples of Compounds

  • Table salt (sodium chloride)
  • Sugar (sucrose)
  • Water
  • Epsom salts (magnesium sulfate) and
  • Alcohol (ethanol)

Compounds made from a combination of elements. Each compound has two or more elements present in fixed ratios by weight. Compounds chemical and physical properties that are quite different from those of their constituent elements.

There are 92 naturally occurring elements, and these are the basic building materials of all matter. In addition, scientists have made a further dozen or so, artificial elements (which have quite short lifetimes). From this mere 92 elements, nature and scientists have made millions of quite different compounds.

When we go deep down into elements under the classification of matter, In addition, Elements made up of tiny particles called Atoms, which we envisage as the little sphere. Also, Atoms are the basic units involved in chemical reactions in the classification of matter.

What is an Atom?

So, according to the classification of matter, Atoms are the smallest particle of an element that can take part in a chemical reaction.

Atoms and Molecules, What is an atom, atom
What is an atom

All the atoms of one element are identical, but they are different from the atoms of all other elements.

When the elements carbon and oxygen react to form the compound carbon dioxide, as a result, each atom of carbon combines with two oxygen atoms to form what we call a molecule of carbon dioxide.

What is a Molecule?

According to the classification of matter, Molecules are the smallest particle of a substance capable of separate existence moreover, molecules are the basic units of compounds.

Likewise, let’s compare the sizes of atoms and molecules.

Sizes of atoms and molecules in the classification of matter

By considering the sizes of atoms and molecules to clarify, Atoms are typically 0.1 to 0.3 nanometres in diameter (1 nanometre = 10-9metre). So, along the edge of a 30cm steel ruler, there are about 1 to 2 billion atoms side by side (1 billion = 109 meter).

Another indication of the small size of atoms is this; So, a one-cent coin has a mass of about 2.5grams and contains about 2 × 1022 atoms; Because of that, a small gain of charcoal (carbon) with a mass of about 1 milligram contains 5 × 1019 atoms.

Molecules are, of course, a bit larger than atoms (since each molecule contains several atoms). In addition, a crystal of sugar (sucrose) with a mass of 10 milligrams contains 2 × 1019 molecules. Since each molecule of sucrose contains 45 atoms (12  carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms), the crystal contains 45×2×1019=9×1020 atoms.

In other words, If atoms were as big as marbles, oranges would be about the size of the earth!

Molecules of Elements in Classification of Matter

In addition, molecules of different elements is an essential field that we should consider.

For example, Oxygen is an element and its symbol is O. However, in the atmosphere, atoms of oxygen do not exist as a separate independent particle but exist combined in pairs and therefore are molecules. In other words stated differently, in oxygen gas, the small particles moving about randomly are molecules, each molecule is a pair of atoms chemically bonded together. Hence for oxygen, the formula is O2. Because of having two atoms Oxygen is considered as a diatomic molecule.

So, according to the classification, This is true for all the common gaseous elements because the smallest particle capable of separate existence is a molecule containing two atoms. Also, these molecules can break into separate atoms in chemical reactions as when magnesium burns in oxygen to form magnesium oxide, MgO.

Further Nitrogen gas is N2, Chlorine gas Cl2, and Hydrogen gas H2. Some of these diatomic gaseous molecules and so-called noble or inert gases, e.g., Helium, Neon, and Argon, exist as free atoms He, Ne, Ar, i.e., as Monoatomic molecules.

Classification Of Matter for further explanations

By considering all the facts discussed above, most importantly we can see that the Classification of Matter is a huge subject that spread so widely in the Chemistry field.

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