9.1.5 Differences between Elements, Compounds and Mixtures
This is the sixth lecture from Chapter 1: ‘States of Matter and Phase Changes’ of the new book for 9th Class Chemistry (Punjab Board – PCTB). It discusses the differences between three common types of matter, i.e., elements, compounds and mixtures.
Descriptive Question
Q1. How would you compare elements, compounds and mixtures?
Elements
Compounds
Mixtures
Elements are the simplest form of matter. They are pure substances because they contain only one type of atom.
A compound is also a pure substance. It is formed by the chemical combination of two or more elements in a fixed ratio.
A mixture is an impure form of matter, created by mixing two or more substances in a random ratio.
There are four types of elements: metals, non-metals, metalloids and noble gases.
Compounds are also classified into two categories: organic compounds and inorganic compounds.
There are two types of mixtures: homogeneous mixtures and heterogeneous mixtures.
An element can exist in different structural forms (allotropy).
A compound can also exist in different structural forms.
Mixtures can exist in multiple forms as well.
Elements cannot be converted into simpler substances by any chemical reaction.
Compounds can be broken down into their constituent elements through chemical reactions — for example, water can be separated into hydrogen and oxygen.
Mixtures can be easily separated into their components using physical methods.
When an element exists as a collection of atoms, it is represented by a symbol — for example, Fe, Ca, and Au.
Compounds have specific chemical formulas that show the types and numbers of atoms. (H2O)
Mixtures do not have any chemical formula or symbol.
Elements can exist either as groups of atoms (e.g., N2, O2) or as single atoms, like in noble gases such as He, Ne, and Ar.
Compounds are always made of different types of atoms chemically bonded together.
Mixtures are formed by physical mixing of substances without any chemical reactions.
Elements have their own distinct properties.
Compounds also have distinct properties.
Mixtures do not have distinct properties. Each component retains its individual properties.
Elements exist in the form of single atoms, molecules, ions, or isotopes.
Compounds can also be found in various forms, such as molecular compounds, ionic compounds, intermetallic compounds, and complexes.
There are many types of mixtures, including solid-solid, solid-liquid, liquid-solid, and more.
He, O2, Fe, Ag
H2O, CO2, NaCl
Milk, Lemonade, Biryani