Compounds

What are the Characteristics of Compound

by

What are the Characteristics of Compounds

Compounds :
A compound is a substance made up of two or more elements chemically combined in a fixed proportion by mass. A compound is formed as a result of chemical reaction, between the constituent elements. The properties of compound are different from the properties of the elements from which it is formed.
What are the Characteristics of Compound 1Ex.       Water (H2O) is a compound made up of two elements, hydrogen and oxygen, chemically combined in a fixed proportion of 1 : 8 by mass
What are the Characteristics of Compound 2Compounds can be further divided into three classes : acids, bases and salts, on the basis of their properties.
Ex.       Sulphuric acid is an acid, sodium hydroxide is a base whereas sodium sulphate is a salt.

Characteristics of a compound

  1. In a compound constituents are present in definite proportion by mass
  2. The properties of a compound are different from the properties of its constituents.
  3. The constituents of a compound cannot be separated by simple physical processes
  4. Formation of a compound is generally accompanied by evolution of energy in the form of heat or light.
  5. A compound has a fixed melting point and boiling point.
  6. A compound is always homogeneous in nature.

Read More:

What are the types of Pure substances and Mixtures

by

What are the types of Pure substances and Mixtures

All the matter around us is not pure. The matter around us is of two types.
In the previous chapter, we have learnt about the three states of matter. Before, understanding the chemical nature of matter, let us first understand the scientific meaning of the term chemical substance.
The scientific meaning of the term chemical substance is different from its everyday meaning. In terms of science, substance is a kind of matter that cannot be separated into other kinds of matter by any physical process. In other words, substance is a pure form of matter and not a mixture of several different kinds of matter. Most of the things that we use in our day-to-day life are in the form of mixtures. Pure substances are rare. For example, the dissolved sugar can be separated from its solution by some physical process (evaporation or distillation). However, sugar is itself a substance and cannot be separated by physical processes into its constituents. Similarly, common salt (sodium chloride), iron, mercury, calcium oxide, hydrochloric acid are substance.
What are the types of Pure substances and Mixtures 1
Pure substances

  • A pure substance consists of a single type of particles.
  • Pure substances are always homogeneous.
  • All the elements and compounds are pure substances because they contain only one kind of particles.
  • A pure substance cannot be separated into other kinds of matter by any physical process.
  • A pure substance has a fixed composition as well as a fixed boiling point and melting point.

Ex.      Hydrogen, Oxygen, Copper, Gold, Silver.

Pure substances can be divided into two types.

  1. Elements  
  2. Compounds

Mixtures
A mixture is a substance which consists of two or more elements or compounds not chemically combined together. All the solutions are mixtures. The various substances present in a mixture are known as “constituents of the mixture” or “components of the mixture”.
Ex.       Lemonade (nimbu pani) is a mixture of water, lemon juice, sugar and salt.
A mixture consists of two or more different type of particles having different chemical nature. Mixture may be homogeneous or heterogeneous. All the mixtures are impure substances. A mixture does not have a fixed composition or a fixed melting point and boiling point.

Types of mixtures
Mixtures are of two types :

  1. Homogeneous mixtures. 
  2. Heterogeneous mixtures.

What Are The Two Types Of Pure Substances

by

Classification Of Pure Substances

Chemical substances are made of atoms and molecules. An atom is the smallest particle of a substance. Atoms may or may not exist independently. Molecules are formed when two or more atoms join together. Molecules can exist independently. Chemical substances can be divided into two major groups: pure substances and mixtures. Pure substances can be elements or compounds.

Classification-Of-Chemical-Substances
Element
An element is a substance that is made up of only one kind of atoms and cannot be broken down into simpler substances by chemical means. For example, silver, gold, aluminium, hydrogen, oxygen, etc. Each element has its own distinct set of properties, thus, the atoms of an element will have all the properties of that particular element.

Compounds
A compound is a substance that is formed when two or more elements combine chemically.
The smallest particle of a compound is a molecule which shows all the properties of that compound. However, the properties of a compound are entirely different from those of its constituent elements.
For example, when hydrogen combines with oxygen, both of which are gas, the liquid named water is formed.

Mixtures
Mixtures consist of two or more substances simply mixed together, but not chemically combined.
For example, air is a mixture of various gases such as nitrogen, oxygen, carbon dioxide, water vapour, argon, and particles of dust, smoke, and many others.

Mixture-of-iron-filings-and-sulphur
Fig. Mixture of iron filings and sulphur

A mixture retains the properties of its components, e.g., in a mixture of iron filings and sulphur, both retain their own characteristic properties, i.e., iron is still attracted by a magnet and sulphur remains as a powder.