Matter/Matter Properties is a part of class 7 chemistry chapters ICSC .Everything around us constitutes matter. It includes living and non-living substances. For example - table, chair, bags, insects, birds etc.
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| What is matter? |
What is matter?
Anything that occupies space and has mass is known as matter. It consists of all living and non living things. Non-living things are divided into two groups i.e pure substances and mixtures. Pure substances are further divided into two categories i.e elements and compounds.
What are elements?
Elements are those pure substances that can't be divided or broken down further by any physical or simple chemical method.For example - hydrogen, helium, silver, nitrogen etc.
What are the characteristics of elements?
Elements are made up of same kind of atoms. All the atoms in an element possess identical properties.Atoms are the smallest unit or particles present in the elements that may or may not have an independent existence.
What are compounds?
Compounds are those substances that consist of two or more elements combined in a fixed ratio. For example -
CO2 H2O
Λ Λ
Carbon Oxygen Hydrogen Oxygen
What are the characteristics of compounds?
* It consists of two or more elements.
For example -
Na + Cl ➡ NaCl
1 atom 1 atom Sodium Chloride
of of (compound)
Sodium Chlorine
C + O + O ➡ CO2
1 atom 1 atom 1 atom Carbon
of of of dioxide
Carbon Oxygen Oxygen (compound)
* It consists of same elements that are combined in a fixed ratio.
For example -
H + O + H ➡ H2O
N + H + H + H ➡ NH3
* Compounds are homogenous.Different samples of a compound possess same properties and are have the same composition throughout.
* The properties possessed by compounds are different from their constituent elements.
For example -
H + H + O ➡ H2O
Hydrogen - combustible and doesn't support combustion
Oxygen - non - combustible but supports combustion
Water - nor combustible neither supports combustion but is used as in extinguishing fire.
Na + Cl ➡ NaCl
Sodium and Chlorine are poisonous while sodium chloride is not poisonous.
* It is not possible to separate the constituent elements of a compound by physical means.
For example
Boiling
H2O ➡ Water Vapours
Compound Compound
Chemical
means
* Energy is absorbed or released during the formation of a compound.
H2+ O2 ➡ H2O (energy + light)
What are mixtures?
Mixtures consist of molecules from elements or compounds or both in any proportion so that they don't undergo any type of chemical change. For example - salty water, milk, soft drinks, cough syrup etc.
What are the characteristics of mixtures?
* The ratio of constituents present in a compound is not fixed.
* A mixture doesn't possess any specific property. The constituents of a mixture don't lose their individual properties.
* For example - Air is a mixture of many gases such as oxygen, nitrogen etc. Oxygen is a supporter of combustion and nitrogen regulates the process of combustion.
* Mixtures don't have fixed boiling or melting points.
What are the types of mixtures?
Mixtures are of two types -
1. Homogenous mixtures
2. Heterogeneous mixtures
1.Homogenous mixtures - In these types of mixtures, the constituents are mixed uniformly and possess the same properties throughout. For example - sea water, air etc.
In the mixture of sugar and water, the molecules are mixed uniformly. We can't see the particles of this mixture separately.All the samples of solution are equally sweet and the sugar-water composition is same in all the samples.
What are alloys?
They are homogenous solid mixtures that consist of metals and non-metals. For example -
Steel - Iron + Carbon
Brass - Copper + Zinc
Bronze - Copper + Tin
2. Heterogenous mixtures - In these mixtures, the constituents are not mixed uniformly and don't have same properties throughout.For example - chalk water, petrol and water, muddy water, iron fillings and sulphur.
States of constituents of a mixture
Mixtures States of constituents
Sand + Salt Solid-Solid
Petrol + Water Liquid-Liquid
Smoke + Air (dust Solid-Gas
particles)
Muddy Water - Liquid-Solid
Note - This chapter has two parts . The link to second part of this chapter Separation of Mixtures is https://lessonstobelearneda-z.blogspot.com/2022/06/separation-of-mixtures.html
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