Mixtures Compounds and Elements | Types, facts, Definition, Simple explanation, |

Element An a element is a substance that cannot be broken down into simpler components by any non-nuclear chemical reaction. 

Mixtures Two or more substances which have been combined such that each substance retains its own chemical identity. 

Compounds A compound is a substance that results from a combination of two or more different chemical elements, in such a way that the atoms of the different elements are held together by chemical bonds that are different to break This is called compound. 

Matter 

• Anything that occupies space and possesses mass is termed as matter. 

Relation between Mass and Energy 

E = mc 

Where, E = Energy obtained 

m = Lost mass 

c = Speed of light = 3 × 10⁸ m/s

States of Matter 

There are three states of matter. 

There are  

1. Solid State The state of matter which has definite shape and volume is known as solid e.g, iron, wood etc.  

2. Liquid State The state of matter which has fixed volume but not fixed shape is known as liquid eg. milk, oil etc. 

3. Gaseous State The state of matter which has not fixed shape and volume is known as gaseous state 

Liquids and gasses are known as fluids.

Change in the State of Matter 

The states of matter are inter-convertible. State of matter can be changed by changing temperature and pressure.

Melting Point 

The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point. The process of melting is known as fusion. The MP of ice is 273.16 K or 0°C. Presence of impurity decreases MP. 

Boiling Point 

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point. Boiling point of water is 373 K or 100°C. Presence of impurity increases BP. 

Freezing Point 

The temperature at which a liquid freezes to solid is known as freezing point. For waters it is 0°C. Presence of impurity increases freezing point. 

• On increasing pressure, BP increases. 

• On hills, atmospheric pressure decreases therefore, water boils at lower temperature than its boiling point. 

• In pressure cooker, pressure on water increases due to which BP of water increases. So, due to higher temperature in cooker, food cook easily in it. 

Evaporation 

The process of change of a liquid into vapours at any temperature below its boiling point is called evaporation. It is a surface phenomenon. 

Sublimation 

It is the change of gaseous state directly to solid state without going through liquid state and vice-versa.

Element 

• An element is a substance which cannot be split up into two or more simpler substances by the usual chemical methods of applying heat, light or electric energy 

• There are 115 elements known at present, out of which 92 elements occur in nature, while remaining 23 elements have been prepared artificially. 

• Elements may be found in all the three forms as solid, liquid or gas. 

Solid  Sodium (Na), Carbon (C), Aluminium (Al) etc. 

Liquid  Mercury (Hg), Bromine (Br) etc. 

Gas  Oxygen (O2) , Hydrogen (H2) etc.

Types of Elements 

Metals 

• The elements which have a tendency to form positive ions (by loss of electrons) are known as metals, e.g., silver, tin, zinc etc. 

• Metals are elements having lustre, ductility, malleability, conductivity etc. 

• Aluminium is the most abundant metal in the Earth's crust. 

Non-metals 

• The elements which have a tendency to form negative ion by gain of electrons are called non-metals e.g., hydrogen, oxygen, sulphur etc. 

• Oxides of non-metals are neutral (in low oxidation state) or acidic (in higher oxidation states) in nature. 

• They are in powder or in gaseous form under normal conditions. 

• Bromine and Mercury  is the only non-metal which is liquid under normal conditions. 

Metalloids 

They are the elements whose properties fall between those of metals and non-metals, e.g., germanium, arsenic, selenium and tellurium etc. 

Symbols 

• The short form used in place of full name of an element is called its symbol. 

• The symbol of an element is the 'first letter' or the 'first letter and another letter' of the English name of Latin name of the element. 

Symbols derived from English Name of the Elements

English Name of the Element	Symbol
Argon	Ar
Bromine	Br
Hydrogen	H
Helium	He
Krypton	Kr
Lithium	Li
Manganese	Mn
Neon	Ne
Phosphorus	P
Silicon	Si
Zinc	Zn
Magnesium	Mg

Symbols derived from Latin Name of Elements 

English Name of the Element	Symbol	Latin Name of the Element
Copper	Cu	Cuprum
Gold	Au	Aurum
Iron	Fe	Ferrum
Lead	Pb	Plumbsum
Mercury	Hg	hydrargysum
Potassium	K	Kalium
Silver	Ag	Argentum
Tin	Sn	stannum
Tungsten	W	Wolfram
Sodium	Na	Natrium

• A symbol represents, name of the element one atom of the element, one mole of atoms of the elements and a definite mass of the elements. 

Mixture 

A mixture is a substance which consists of two or more elements or compounds not chemically combined together, e.g., air, milk, ink, brine, lime water, glass, paints, soil, food, wood, kerosene etc. 

Types of Mixtures 

Mixtures are of two types. 

Hemogeneous Mixture 

A homogeneous mixture has the same composition throughout its mass. It has no visible boundaries of separation between the various constituents, e.g., solution of sugar in water, solution of salt in water, a mixture of alcohol and water etc. 

Heterogeneous Mixture 

A heterogeneous mixture does not have a uniform composition throughout its mass. A heterogeneous mixture has visible boundaries of separation between the various components, e.g., solution of K2Cr2O7, in water, solution of CaCO3 in water, solution of oil in water, gun powder, soil etc. 

• A mixture which boils at a definite boiling point is called azeotropic mixture.

Changes Occurring in Matter or Substances 

There are two types of changes in matter. 

Physical Change 

It is a temporary change. No, new substance is formed, e.g., melting of ice, sublimation of iodine etc. These changes are reversible.

Chemical Change 

In this change, chemical composition and properties of the substance changes permanently, i.e. new substance is formed, e.g., rusting of iron, burning of magnesium wire, etc. These changes are irreversible. 

Properties of a Mixture 

• A mixture can be separated into its components by physical methods like, filteration, evaporation, sublimation, distillation, magnet etc. 

• A mixture shows the properties of all the constituents present in it.

• Energy is usually neither given out nor absorbed during the preparation of a mixture. 

• The composition of a mixture is variable, ie., the constituents can be present in any proportion by weight. 

• A mixture does not have a definite melting point, boiling point etc. (except azeotropic mixture). 

Methods of Separation of Mixture 

1. Crystallisation  This method is based on the difference in the solubility of the compound and the impurities in a solvent e.g., a mixture of KNO3 and NaCl can be separated by this process. 

2. Distillation  This method is used for the purification of liquids which boil without decomposition and contain non-volatile impurities, e.g., pure water can be obtained from sea water by distillation. 

3. Fractional Distillation  This process is used to separate a mixture of two or more miscible liquids which have boiling points close to each other e.g., petrol, diesel, kerosene etc. 

4. Sublimation  This process is used for the separation of those solids which sublime from a non-volatile solid This process is generally used for the separation of naphthalene anthracene, benzoic acid, camphor, NH4Cl, iodine etc. 

5. Distillation Under Reduced Pressure  It is used for liquids which decompose below their boiling points. It is also called vacuum distillation, e.g., glycerol can be separated by this method. 

6. Steam Distillation  It is used for the separation and purification of liquids which are appreciably volatile in steam from non-volatile impurities of mixture, e.g., o-nitrophenol and p-nitrophenol are separated by this method. Aniline is also purified by this method.

7. Evaporation  It is the process by which soluble solids can be obtained from their solution by allowing the solvent to vaporise, e.g., salt can be obtained from salt solution by evaporation. 

8. Chromatography  Chromatography is a moden method proposed by Tswett in 1903. This method is based on the difference in the rates at which the components of a mixture are adsorbed on a suitable adsorbent. This method has been used to separate blue and red dyes, to separate plant pigments and other natural products. 

9. Atmolysis  It is used for separating the mixture of gases. This method is based on the difference in their rates of diffusion.

Compounds 

A compound is a substance made up of two or more elements chemically combined in a fixed proportion by weight, eg. water, NaCl, NH4Cl and CO2 etc.

Organic Compounds 

Component	Functional Group	Name of Functional Group
Hydrocarbon
(i) Saturated	≡C–C≡	Paraffin bond
(ii) Unsaturated
(a) Olefin	>C=C<	Olefin bond
(b) Acetylene	–C≡C–	Acetylene bond
Halogen compound	–Cl, –Br, –I	Chloro, bromo, and iodo
Alcohol	R–OH	Hydroxy group
Ether	R'–O–R	Ether group
Aldehyde	R–CHO	Aldehyde group
Ketone	>C==O	Oxo and keto group
Carboxylic acid	–COOH	Carboxylic group
Ester	–COOR	Ester group
Nitro compound	–NO2	Nitro group
Amine	–NH2	Amino group
Amide	–CONH2	Amide group

Properties of Compounds 

• A compound cannot be separated into its components by physical methods. 

• The properties of a compound are entirely, different from those of its constituent elements. 

• The composition of a compound is fixed, ie., the constituents are present in fixed proportion by weight. 

• Compounds have fixed melting point and boiling point etc. 

• A compound is a homogeneous substance. 

Chemical Formulae 

The chemical formula of a compound represents the composition of a molecule of the compound in terms of the symbols of the elements present in it, e.g., a formula of H2O represents that water has two atoms of hydrogen element and one atom of oxygen element. 

Method for Writing the Formula 

If we want to write the formula of a compound which is made up of two elements having valencies x and y, respectively. 

It can be done as follows 

1. Write the symbols or formulae of the basic radicals to the left and acidic radicals to the right. 
2. The valency of each radical is written on the radicals.
3. The criss-cross rule is applied by exchange of numerical value of valency of each radical. 
4. A complex radical (or compound radical) is enclosed in brackets and the subscript is written outside the lower right hand corner. 
5. A common factor is eliminated and unit subscript is omitted. 

For Example (i) Calcium chlorite 

(a) Symbols are written with their valencies Ca²+(CIO2)¯. 

(b) Exchange the numerical value of valency of each radical. 

2            1

× 

Ca      ClO2

(c) Omitting the unit subscript, the formula of calcium chlorite is Ca(CIO2)2.

Types of Formulae 

Empirical Formula 

The empirical or simple formula of a compound shows the simplest whole number ratio of the atoms of various elements present in one molecule of the compound. e.g., the empirical formula of acetylene is CH and that of glucose is CH2O. 

Molecular Formula 

It gives the actual number of atoms of component elements in one molecule of the compound. e.g., the molecular formula of fructose is C6H1206. 

Calculation of Empirical and Molecular Formula 

The empirical formula of a compound is calculated from the percentage composition of compound as follows 

• The percentage of each element is divided by its atomic weight to get the relative number of atoms of various elements present in the compound. 

• The relative number of atoms is divided by the minimum value to have the simplest ratio of the number of atoms. 

• If the simplest ratio is not a whole number then it is made a whole number by either changing the value to the nearest whole number or by multiplying with a suitable integer throughout. 

• The whole number is written as a subscript at the lower right hand corner of the symbol of the element to give the empirical formula.  

• The empirical formula weight is calculated by adding the atomic weight of atoms of all elements present in empirical formula. 

• The molecular weight of the compound is calculated from the given data. 

• 'n' is calculated by using the relation 

    n = Molecular weight of the compound / Empirical formula weight 

• Molecular formula = (Empirical formula) × n 

Chemical Equations 

• A chemical equation is the symbolic representation of an actual chemical change, e g, 

Zn + H2SO4  –––– ZnSO4 + H2 ↑ 

• A chemical equation represents

• compounds taking part in the reaction. 

• products or compounds formed during the reaction. 

• catalysts used for the reaction (If any).

Important  TIPS  

• Silicon (Si) is an element and silica (SiO2) is a compound.  

• Oxides of metals are basic and non-metals are acidic.  

• Crystallisation is based on difference in solubility. 

• Mixture which boles at definite boiling point is called azeotropic mixtures.  

• NH4CI sumblimes due to its decomposition into NH3 and HCl.  

• I2 is the only halogen which sublimes.  

• A compound is always homogeneous. 

• Ants contain formic acid (HCOOH).   

• Urea is the first organic compound prepared in laboratory by Wohler in 1928.  

• Acetic acid is the first organic compound which is extracted from natural material by Kolbe. 

• Methane is the first organic compound which is synthesised in laboratory from its elements by Berthelot.

Related Questions : (Answer in comment box.)

Q1. Magnesium is present in 

(a) haemoglobin 

(b) vitamin B2 

(c) chlorophyll 

(d) ascorbic acid

Q2. An azeotropic mixture is a mixture which has 

(a) constant boiling point 

(b) all components have different boiling points 

(c) maximum amount of components 

(d) None of the above

Q3. A mixture of red and blue ink can be separated by 

(a) Distillation 

(b) Chromatography 

(c) Crystallisation 

(d) Sublimation

Q4. Which one of the following is the most abundant metallic element? 

(a) Aluminium 

(b) Gold 

(c) Iron 

(d) Silver

Q5. First organic compound which was prepared in laboratory is 

(a) methane 

(b) formaldehyde 

(c) urea

(d) water

Q6. Formula of nitrate of a metal is M(NO3)3 the formula of its pyrophosphate is 

(a) M3(P2O7)4

(a) M(P2O7)2

(a) M2(P2O7)3

(a) M4(P2O7)3

Q7. Which of the following is a compound? (a) Ozone 

(b) Diamond 

(c) Marble 

(d) Quick silver

Q8. On hearing 200 g CaCO3 CaO is obtained which will react with how much gram of water to obtain Ca(OH)2? 

(a) 200 g 

(b) 112 g 

(c) 36 g 

(d) 40 g

Q9. The percentage of zinc in ZnSO4 7H20 is (Zn = 65, S = 32, O = 16, H = 1) these 

(a) 23 

(b) 13 

(c) 17 

(d) 33 

Q10. Which of the following contains maximum number of atoms? 

(a) 2.0 mol of S8 

(c) 5.5 mol of SO2 

(b) 6.0 mol of S 

(d) 44.8 L of CO2 at S.T.P

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