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What is a Pure Substance? Easy Guide For Students!

pure substance

When you’ll look around yourself, you’ll find tons of materials, like, cars, books, colors, etc. All of these things are made up of atoms and molecules. However, these substances support unique structures of atoms and molecules. Scientists have divided these things (also known as matters) into categories, such as pure substances and impure substances.

Dive in to learn everything about pure substances.

Definition:

Pure Substance!

“Pure substances are made up of identical particles and hold consonant chemical composition.”


By identical particles, I mean that a pure substance contains the same kind of atoms, molecules, or elements. For instance, pure copper has only copper elements that are the same in size and properties. On the other hand, peanut butter is impure as it is made up of different substances, like, salt, peanut, butter, etc.

Related Read: Make chemistry easy to learn with these tips

What Are the Two Main Categories of Pure Substance?

Pure substances are further classified into elements and compounds, just as shown in the image below:

Two Main Categories of Pure Substance

Elements

Elements are substances that are made up of only one kind of particle that share identical shapes, sizes, and properties. Further, they cannot be separated by physical means or chemical processes. The most common examples of elements are oxygen, carbon, etc.

Scientists use symbols for representing elements. The standard periodic table of elements has a total of 118 pure substances.

What are transitional elements?

All the elements in block d from groups 3 to 12 are called transitional elements. We call them transitional elements because their oxidation states are variable. Such as Fe(+2) and Fe(+3).


periodic table

Compounds

The second type of pure substance is a compound. Compounds have two different particles that are formed by mixing a fixed ratio of unlike atoms together with help of a chemical reaction called ionic bonding. Unlike elements, the particles of compounds can be separated by chemical means. The most common compounds are shown in the image below:

Common Chemical Compunds


What is ionic bonding?

When one atom donates one or more electrons to another atom, it forms a chemical bond called an ionic bond.


As now you know what pure substances are, let’s shed some light on the properties of pure substances.

Properties of Pure Substances

  • Pure substances have fixed melting and boiling points.
  • These substances are homogenous, meaning that they have consonant composition.
  • Pure substances are usually chemically mixed with each other to form predictable substances.
  • These substances cannot be broken down into new substances.

List of Pure Substances

Pure Substance

Element or Compound?

Lead (Pb)

element

Helium

Element

Water (H2O)

compound

Nitrogen (N)

Element

Oxygen gas (O2)

element

Ammonia (NH3)

compound


Frequently Asked Questions About Pure Substances

=> What is the difference between pure substances and mixtures?

In chemistry, pure substances contain identical particles that are chemically combined. On the other hand, mixtures are substances that have different particles that are not chemically joined together.

=> Is water a pure substance?

Yes. Water (H₂O) is a pure substance. It is formed by the same types of molecules. The two hydrogens and oxygen are chemically bonded together in a fixed composition.

=> How can you identify a pure substance?

To check whether a substance is pure or not, you’ve to look at its structure. If the substance is made up of only one type of compound or one type of element, then it's a pure substance.

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