Kinetic theory of matter

The theory has been put in forward to explain the force between molecules and the energy the molecules theory of matter are

Here are the basic prostulated theory of matter.

(i) *Matter in all its forms ( solid, liquid and gas) is composed of tiny particules*

The Kinetic Theory of Matter states that matter is composed of a large number of small particles—individual atoms or molecules—that are in constant motion. This theory is also called the Kinetic-Molecular Theory of Matter.

By making some simple assumptions, such as the idea that matter is made of widely spaced particles in constant motion, the theory helps to explain the behavior of matter.

Matter consists of small particles

The first assumption in this theory is that matter consists of a large number a very small particles—either individual atoms or molecules.

All matter (solid, liquid, and gas) is made up of tiny particles called atoms, or atoms that are joined to form molecules.

(2) *When the molecules collide with each other there is no loss of energy*

The ability to collide over each other's differs from state to the other.

The next assumption is concerned with the distance apart of the particles.

In a gas, the separation between particles is very large compared to their size, such that there are no attractive or repulsive forces between the molecules. Hence, the particles collide more with each other or with the wall of their container

In a liquid, the particles are still far apart, but now they are close enough that attractive forces confined the material to the shape of its container. The particles in liquid state moves freely and do collide less compare to gas particles.

Whe in a solid, the particles are so close that the forces of attraction confined the material to a specific shape. The collision is less compare to liquid.

Particles are in constant motion

Another assumption is that each particle is in constant motion.

Note: The closer the particles the greater their attractive force while how separate they are determines their collisions 

(3) *They possess kinetic energy*

In gases, the movement of the particles is assumed to be random and free.

In liquids, the movement is somewhat constrained by the volume of the liquid.

In solids, the motion of the particles is severely constrained to a small area, in order for the solid to maintain its shape.

The velocity of each particle determines its kinetic energy. There is an exchange or transfer of energy between particles—both atoms and molecules—during a collision between them.

The magnitude of the kinetic energy are in three state of matter. That's the the kinetic energy needed

Solid paricles > liquid particles > gas particles

Terms used in explaining kinetic theory.

It's illustrate by some natural phenomenon. Which are :

a. *Brownian motion movement*: is a rapid and Zig-zag motion caused by collision between tiny/ minute particles of water. E.g. Smoke from a chimney, colloidal particles in water and a particles of pollen in water ( examined by ultra-microscope). Brownian only occur  in liquid and gas state.

b. *Diffusion*: is the movement of molecules of a substance from one point of higher concentration to a region of lower concentration. For instance, if a perfume is sprayed in one corner of a room, it molecules will move to all part of the room within a short time. What simply occurred is known as  DIFFUSION. Diffusion also occur in liquid but at a slower rate compare to gas. It's hardly occur in solid at a low temperature but it becomes appreciable at higher temperature.

c. *Effusion*: is the movement of molecules of gas particles through a tiny orifice into an evacuation chamber.

d *Osmosis*:  It the movement of solution ( solvent + solute) from a region of lower concentration to a region of higher concentration through a semi- permeable membrane.

e. *Dissolution*: is the intimate mixing of the particles of the molecules of solid of solute to that of its solvent.

F.  *Sublimation*: is the change of a substance in solid state to gas state directly without passing through the liquid state by heat. When heated the when arranged molecules of the solid overcome the cohesive forces and becomes rapidly and randomly, hence, change into gas state.

g.  *Evaporation*: It the stead change of a liquid to its vapour. For this to occur the particles of liquid my occasionally, acquire kinetic energy of the molecules. Hence, over comes the attractive forces at the liquid surface and escape from the cohesive forces at the liquid surface into the vapour phase.

Summary

The Kinetic Theory of Matter states that matter is composed of a large number of small particles that are in constant motion. It also assumes that particles are small and widely separated. They collide and exchange energy. The theory helps explain the flow or transfer of heat and the relationship between pressure, temperature and volume properties of gases.

See introduction to chemistry

CHEMICAL COMBINATION

 

Chemical bonding deals with the study of formation of compounds out of elemental forms of atoms. A chemical bond is the result of the attraction between atoms or ions. Chemical compounds are formed by the joining of two or more atoms. The type of bonds that a molecule contains will determine its physical properties, such as melting point, hardness, electrical and thermal conductivity, and solubility. Various forms of bonding may be classified into the following types.

Ionic Bonding: The other name of Ionic bonding is electrovalent bonding; the molecular linkages are formed by the electrostatic attraction among oppositely charged ions. The attraction phenomenon is influenced by the formation of bond between molecules with the help of complete valence electron transfer from one atom to another. The atom which loses electron(s) are positively charged and named as cation and the one that gains electron(s) are named as anion which have negative charge. The best ionic bonding can be seen in the combination of non-metals, alkali and alkaline-earth metals. In molecular formation, like charges gets repulsed and those being oppositely charged, gets attracted in which each positive ion is surrounded by negative ions in attraction forming a net zero balance of ions for the stable ionic compound. The ionic bonds are also referred as extreme form of covalent bond, which happens only during a great difference in electronegativity of the participating atoms.

Covalent and Metallic Bonding: The sharing of electron pair among two atoms results in interatomic linkage termed as covalent bonding where the electrostatic occurs between the atoms having similar electronegativity resulting in binding process. Less the difference in the electronegativities, more is the strength of the covalent bond. A covalent bond is expected to form the bonding with lowest energy.The covalent bonds can also be formed other than in organic compounds. Inorganic substances like water, chlorine, ammonia, nitrogen and hydrogen also exhibit covalent bonding.

The single line represents single bond, two lines for double bonds, three lines for triple bonds which are represented symbolically as . The metallic bonding not being like ionic or covalent bonding, it is formed by the attraction of valence electrons and metal ions. In simple representation, many electrons surrounding the metal ions acts as glue in bond formation termed as metallic bonding. The loosely bound electrons forming a “sea” of floating valence electrons is the characteristic of metallic bonding. This very nature accounts for the highly electrical conductivity to metals.

COVALENT BONDS

Covalent chemical bonds involve the sharing of a pair of valence electrons by two atoms, in contrast to the transfer of electrons in ionic bonds. Such bonds leads to stable molecules if they share electrons in such a way as to create a noble gas configuration for each atom.

Hydrogen gas forms the simplest covalent bond in the diatomic hydrogen molecule. The halogens such as chlorine also exist as diatomic gases by forming covalent bonds. The nitrogen and oxygen which makes up the bulk of the atmosphere also exhibit covalent bonding in forming diatomic molecules.

Examples of covalent bonding

1) Chlorine: Two chlorine atoms could both achieve stable structures by sharing their single unpaired electrons. The two chlorine atoms are said to be joined by a covalent bond. The reason that the two chlorine atoms stick together is that the shared pair of electrons is atttached to the nucleus of both chlorine atoms.

2) Hydrogen: Hydrogen atoms only need two electrons in their outer level to reach the noble gas structure of helium. Once again, the covalent bond holds the two atoms together because the pair of electrons is attracted to both nuclei.

3) Hydrogen Chloride: The hydrogen has a helium structure and the chlorine has an argon structure.

IONIC BONDING (ELECTROVALENT BONDS)

In an ionic bonds, an electron is actually transferred from the less electronegative atoms (metals) to the more electronegative elements (non metals). Ionic bonds are the result of an electrostatic attraction between ions that have opposite charges; in other words, cations and anions. Ionic bonds usually form between metals and non metals. Ionic bonds are very strong, so compounds containing thses types of bonds have high melting and boiling point and exist in a solid state under standard conditions.

Ionic Bonding in Sodium Chloride

Sodium (2,8,1) has 1 electron more than a stable noble gas structure (2,8). If it gave away that electron it would become more stable while chlorine on the other side (2,8,7) has 1 electron short of a stable noble gas structure(2,8,8). If it could gain an electron from somewhere it too would become stable.

The answer is obvious. If a sodium atom gives an electron to a chlorine atom, both become more stable. The sodium has lost an electron, so it no longer has equal numbers of electrons and protons. Because it has one more proton than electron, it has a charge of +1. If electrons are lost from an atom, positive ions are formed. Positive ions are sometimes called cations.

The chlorine has gained an electron, so it now has one more electron than proton. If therefore has a charge of 1- . If electrons are gained by an atom, negative ions are formed. A negative ion is sometimes called an anion. The sodium ions and chloride ions are held together by the strong electrostatic attractions between the positive and negative charges. One sodium atom to provide the extra electron forone chlorine atom, so they combine together 1:1 . The formula is therefore NaCl.

Some other examples of ionic bonding

1) magnesium oxide: Again, noble gas structures are formed, and the magnesium oxide is held together by very strong attractions between the ions. The ionic bonding is stronger than in sodium chloride because this time you have 2+ ions attracting 2- ions. The greater the charge, the greater the attraction.

Mg  2,8,2                     Mg²⁺  2,8

O    2,6         ----->           O²⁻    2,8

 The formula of magnesium oxide is MgO

2) Calcium chloride: 

Cl  2,8,7                 Cl⁻      2,8,8

Ca 2,8,8,2   ---->     Ca²⁺  2,8,8

This time you need two chlorines to use up the two outer electrons in the calcium. The formula is therefore CaCl₂.

3) Potassium oxide: 

K   2,8,8,1.             K⁺.   2,8,8

O.  2,6.                   O²⁻  2,8

Again, noble gas structure are formed. It takes two potassiums to supply the electrons the oxygen needs. The formula of potassium oxide is K₂O.

The atoms in solid state like ionic bonded molecules arrange in patterns of order termed as lattice which is the space of minimum energy stored. The ionic lattice forms in ionic bonding while in covalent bonds a bigger lattice structure is formed and molecular lattice is formed in intermolecular bonding. In general, there are fourteen types of lattice commonly named as Bravais lattice and the types of lattice formed in atoms and molecules are:

1) Cubic crystal with at all axes

2) Hexagonal with four crystallographic axes forming at three horizontal axes

3) Tetragonal with one perpendicular axes and other two in.

 Key Points:

Ionic bonds are formed by complete transfer of valence electrons from one atom to another, between atoms having the greatest difference in their electronegativities.

Covalent bonds are formed by sharing of valence electrons, between atoms having minimal difference in electronegativities.

Metallic bonding occurs between atoms within a metal and has a “sea” of floating electrons on the surface.

In the solid state, the ionic, covalent and metallic bonding, all are arranged in definite geometrical shapes which are known as lattices.

The measurement of the atoms tendency to attract the bonding pair of electrons are termed as electronegativity and the formal charge among the atoms / molecules represents its resonance state. The tool used to measure electronegativity of the atoms / molecules is the Pauling scale where least electronegative atoms are Caesium and Francium with the value of 0.7 and the most electronegative atom is Fluorine with 4.

The polar and non-polar bonding of the molecules are determined using electronegativity values, in polar bonds the one of the molecule is slightly positive and other end of the molecule is slightly positive favouring the dissolution of the molecule where as in non-polar molecules the charge in both the ends are not balanced it exists in uneven distribution results in non-dissolution of the atoms / molecules.

There are three main points about electronegativity

The non-polar covalent bond exists when no electronegativity difference occurs.

Only a small electronegative difference results in the formation of polar covalent bonds.

The ionic bond results from the large electronegative difference.

The existence of molecular and ionic shapes occurs by the repulsive and attractive forces that exist within molecules and ions and generally accepted view is “The shape adopted is the one which keeps repulsive force to a minimum”. The types of molecular shape existence are listed below with the appropriate bond angle reference,

Linear with 2 bond pairs of  bond angle

Trigonal planar with 3 bond pairs of bond angle

Tetrahedral with 4 bond pairs of bond angle

Trigonal bipyramidal with 5 bond pairs of bond angle combination

Octahedral with 6 bond pairs of bond angle

 

Key points:

Electronegativity of atoms determines the nature of chemical bond formed between them.

Attractive and repulsive forces operating within molecules and ions determine their shapes.

See introduction to chemistry 📝

SEPARATION TECHNIQUES

 

SEPARATION TECHNIQUES

    A mixture contains two or more different substances physically combined together.

   Each constituent in a particular mixture still retains its individual properties, i.e, the properties of each substance in a particular mixture is still the same as when it wasn't mixed up with any other Substance.
    Due to the physical properties of substances in a mixture,a mixture can be separated into its components by physical technques or methods,Using the physical properties of its constituents.

TYPES OF SEPARATION TECHNIQUES.

1) SIEVING:

Used to separate solid particles of different sizes.

   A material called mesh,is used to separate the smaller particles from the bigger ones.
    Industries such as mining and garri industries,make use of this method.

2) MAGNETIC SEPARATION

       This is used to separate magnetic substances from non-magnetic ones.

   It is used in steel industry and to remove magnetic impurities from tin-ore.

3) SUBLIMATION.

    Some solids like ammonium chloride and iodine,when heated,sublimes, i.e,they change directly from solid to gaseous state, without Changing first to liquid.
   These types of solids can be separated from other solids of by sublimation because of  their sublimation property  and are purified industrially by the same method.

Sublimation

4. DECANTATION.

    This is used to separate a mixture of a liquid and solid particles that cannot mix together (They seperate into two distinct layers on standing).

 For example,garri and water.  The liquid is poured out or decanted to separate it from the garri but this method is  inaccurate in seperating mixtures.

Decantation

5) FILTRATION

     This is used to separate insoluble particles ( particles that cannot dissolve in liquids) from liquids.

   It is used in industries such as breweries and in purifying water.

   A pourous material is usually used.

Seperation by filtration.

CENTRIFUGATION.

          This  is used to separate  the components of a suspension.  A mach- ine called centrifuge is   used to spin test tubes containing suspensions at high speeds which causes the heavier solid particles in the suspension to go to the buttom of   the test tube,  while the liquid in the test tubes  seperates as an upper layer which can then be poured   out.
   Centrifugation is used for only a small amount of mixture. For example, in hospitals,blood cells are seperated from the plasma by centrifugation.

A Centrifuge.

7) FLOATATION.

   Used in seperating metals from their ores.

8) EVAPORATION TO DRYNESS.

  This is used to recover a solid(the solute) from a solution. In this case,the solvent is lost. This is done using a heated water-bath.

( Solute + solvent =Solution.)

The process of  obtaining Salt from its solution by evaporation.

  Evaporation is the process by which liquid changes to vapour.
 It takes place at all temperatures.
  This process is used in salt-making industries.

9)CRYSTALLIZATION

    This is used in seperating salts that decompose easily when heated,from their solutions.

   The salt produced this way are pure and usually contain water of crystallization.
   It involves heating the salt solution first to make it saturated.When the saturated salt solution cools off,the salt crystals begin to form.

Crystallization.

10) Fractional crystallization.

    When there are two or more solid solute particles in a solution in roughly equal amount,fractional crystallization is used to separate the needed substance (s) from the solution, using the solubility of the different solutes in the solvent.

   The solubility of these solutes must be different, i.e,the temperature at which a solute dissolves must be different from the one at which the other solutes dissolves in the given solvent.

   At a particular temperature, crystals of the relevant solute comes out of the solution(after they had dissolved), leaving the others which are still within their limits of solubility.


 

11) Precipitation.

    When we have a solid,which has different solubilities (rate at which it dissolves),in two different liquids that can mix together,such as water and ethanol.
Precipitation process is used to separate the solid from the liquids.The solid usually dissolve in one of the liquids.
    Forexample,Iron(II)tetraoxosulphate(VI) is soluble (dissolves) in water but not in ethanol (which can mix with water).
     If ethanol is added to a solution of iron(II) tetraoxosulphate (VI) in water,the solid will be precipitated out of the solution and can be seperated by filtering the liquids from it.

12) Distillation.

    This is used to recover a solvent from a solution.

      When we have two liquids in a solution,and they can mix together,and boils at widely different temperatures, distillation can also be used to recover the liquid needed or solvent from the solution.

   The solution is heated in a flask to vapourize the liquid or solvent (called
 EVAPORATION).   The vapour of the solvent or liquid that boils faster(using a thermometer to detect the boiling point) in  order to  vapourize travels alonga condenser called  the liebig  condenser, which  is cooled by the circulating  water  in the outer jacket of the condenser.

   This cooling effect changes the vapour back to liquid,called the distillate,which is then collected in a receiver.
  The solute and other impurities are left behind in the flask.

Distillation.

     Distillation is used in gin and water distilleries for the production of gin and distilled water respectively.

13) Fractional   Distillation.

 

 This is used to separate a mixture of two or more miscible liquids that has little difference in their boiling points. i.e,the boiling point of one liquid is not far from that of the other in the mixture.

    The fractions of liquids distil over in ascending order of their boiling points, starting with the liquid with the lowest boiling point and for this process to be efficient,the difference in boiling point must be more than 10°C.

  The apparatus used are a fractionating column, liebig condenser,retort stand,tripod stand,round and flat buttom flasks,and thermometer.

Fractional Distillation.

    Crude oil is seperated into it's fractions such as petrol,kerosine, Diesel,bitumen,etc,by fractional distillation.

14) seperating funnel method.

   This is used to separate two or more liquids that cannot mix together.The liquids seperates into two or more distinct layers when added together.

   A seperating funnel is used in which the denser liquid layer below is tapped off,while the less dense liquid layer below remains in the funnel.

Seperating funnel method

15) chromatography.

   This is used to separate a mixture such as ink,dye,and amino-acids,etc, into its components through a porous,absorbent medium like paper .

   There are various methods of chromatography such as:

a) Ascending  Paper    chromatograpy

b) Gas Chromatography

c)Thin-layer chromatography

 Chromatography is used in scientific research to identify and analyse substances and in petroleum industries to identify the various components of the fractions such as kerosene and Diesel,obtained from the Distillation of crude oil.

Paper chromatography

   It is used to determine the presence of certain substances in urine and blood of patients to help doctors in their diagnosis.
It is also used to check the components of chemical products.
A substance can be purified using the appropriate seperation techniques.

 TESTS FOR PURITY

   The following are the criteria to determine the purity of a substance:

1) The melting(for a solid) or boiling point (for a liquid) of a substance is always constant at a specific temperature,if impurities are present in the substance,the specific temperature is affected,it changes.
  If the temperature wasn't affected,then the substance is probably pure.

   Impurities increases the boiling point of a substance while it decreases the melting point of a substance. That is,if a liquid or solid is not pure,it will boil at a range of temperatures above or higher than the boiling point of the liquid or melt at a temperature below or lower than the melting point of the solid.

This is applied in countries with low temperature conditions below 0°C to melt the ice on their roads faster by sprinkling salt which serves as an impurity in the ice,hence lowering its melting point so it could melt faster.

2) On a paper chromatogram,a pure substance will give only one stop.

See NATURE OF MATTER

INTRODUCTION TO CHEMISTRY

INTRODUCTION 

TO CHEMISTRY.

Anything that is known to have mass and occupies space is called MATTER. This means everything around us is matter,which can either be SOLID, LIQUID or GAS(the physical states of matter).

The scientific study of the structure, composition, properties, the reactive characteristics and uses of matter is called chemistry.

   

   The reactive characteristics of matter is the ways in which different forms of matter combine with each other.

We study chemistry in order to understand the world around us,thus chemistry is the study of everything around us.

Through the process of science,a study is conducted on a particular matter, series of observations are made about such matter which may have a pattern and this often lead to a problem to be solved.

A reasonable or proposed explanation or an "educated guess" called HYPOTHESIS,is put forward to explain the observations made earlier.This hypothesis can change as it is not yet tested to be true.

 When experiments are made to test the hypothesis,and is found to be correct based on a body of facts that have been repeatedly confirmed through observations and experiments,within the limits of available evidence,the hypothesis becomes a THEORY. 

A Scientific theory is a comprehensive explanation of an important part of nature supported by facts gathered over time and repeatedly confirmed through observations and experiments.Theories are no longer guesses but reliable accounts of the real world.They are proven explanations on observations about something.

  A SCIENTIFIC LAW or PRINCIPLE is then established when the theory has been extensively tested and proven to be true without any exception.

A Scientific law refers to rules for how a particular aspect of nature will behave under certain conditions.This is mostly written as an equation.

The difference between a Scientific theory and a scientific law is that theories explains the reasons for our observations while laws describes what happens.

If the experiments does not support the hypothesis,it is either modified or a new one is produced.

  

This process of studying a problem in science is called the    

SCIENTIFIC METHOD.

{Observations--patterns----problems

----hypothesis

----experiments

----theory

----Law.

USES AND APPLICATION OF CHEMISTRY.

These are some of the various uses of chemistry:

 1) food supply:

 The production of fertilizers such  as urea, calcium,sodium nitrate,etc , pesticides and insecticides has helped to increase the production and protection of food crops from pests greatly.

  

2) Contribution to improved health and sanitation facilities:

through the production of life-saving drugs such as analgesics, antibiotics, tranquilizers, antiseptic, disinfects, anaesthetics and insecticides.

3) clothing:

textile fibres are produced as a result of intensive chemical research.

4)provisions of explosives has helped in military and space science.

5)In building and construction:

Materials such as steel, cement,concrete, bricks, etc,are essential chemical products in building.

6)In transport and communication:

Petrol, diesel or coal are essential chemical products used in transportation.

7) production of nuclear energy 

8) chemistry has helped in the development and growth of industries like glass,cement, paper, textile, leather,dye, petroleum industries,sugar, plastics and pharmaceutical industries,etc.

BAD EFFECTS 

OF CHEMISTRY.

1) pollution by chemical wastes from factories,oil refines and animal life.

2)rusting of iron:this is the slow deterioration from iron to iron(III) oxide in the presence of water and oxygen in air.

3)Drug abuse:drugs like heroin, cocaine and morphine are addictive.

Hope you understand?

See chemical combination

NATURE OF MATTER

THE NATURE OF MATTER

Matter is anything that has mass and occupies space. The mass of an object is the quantity of matter contained in such object. 

 PROPERTIES OF MATTER.

 

1. Physical properties : 

These are the properties of matter associated with physical change.

When a particular aspect of matter undergoes a physical change,no new substances are formed.

Examples of physical properties of matter are boiling and melting point, density, colour, odour,taste, malleability,change of state,etc.

Examples of physical changes are the dissolution of salt in water, freezing of liquid to solid,eg,water to ice,the sublimation of solid to gas,the vaporization of liquid to gas,etc.

2. Chemical properties:

  These are the properties of matter associated with chemical changes.

A chemical change is the one which cannot be easily reversed and in which new substances are formed.

Examples of chemical changes the dissolution of metals and limestone in acid, the rusting of iron, the addition of water to quicklime, the fermentation and decay of substances, etc.

CLASSIFICATIONS OF MATTER.

Matter is basically classified into two groups namely:

 1. Pure substances:

These are substances that has constant chemical composition and properties.

It is further divided into ELEMENTS (metals, non-metals metalloids and Noble gases),

and COMPOUNDS

(Ionic and molecular compounds).

2.Impure substances:

 These are substances formed from the combination of two or more pure substances which could be elements and/ or compounds.

  

Impure substances are also called MIXTURES.

 Mixtures can be homogeneous (solution or colloids) or 

Heterogeneous

(Suspension or colloids).

DEFINITION OF TERMS.

ELEMENTS:

An element is a substance that cannot be separated into simpler units by chemical methods.

There are 118 known elements in the world.

Elements are grouped into:

(a) METALS:

    Metals are elements that ionize by losing electrons to form cations.

examples are calcium,sodium, magnesium, potassium, etc.

PROPERTIES OF   METALS.

1.They are malleable, ductile or sonorous (produces sound)

2.They are lustrous.

3.Good conductors of heat and electricity.

4.High melting and boiling point.

5.High density

6.They have great tensile strength (hardness)

7.They are reducing agents.

8.They form basic oxides when they react with oxygen.examples are Magnesium oxide (MgO), sodium oxide, potassium oxide, etc.

9.They form ionic compounds.

(b) NON-METALS

    Non-metals are elements that ionize by gaining electrons to form negative ions.

examples are chlorine, oxygen, Nitrogen,Iodine,etc.

Properties of non-metals:

 1.They are oxidizing agents.

 

 2.They form acidic oxides when they react with oxygen.eg.

Carbon(iv)oxide, sulphur (vi) oxide,etc.

3.The physical properties of non-metals are the opposite of that of metals, except for the case of melting and boiling point in carbon,a non-metal which has high melting and boiling point like metals.

(C) METALLOIDS.

  These are elements that has intermediate properties between those of metals and non-metals.

  It is also called a SEMI-METAL.

Examples are Antimony,Boron, Silicon,Germanium

Arsenic,and tellurium.etc.

Metalloids tends to be semi- conductors,since they share the properties of metals and non-metals, silicon is a very good example of a semiconductor.

(D)NOBLE GASES.

 These are elements that have low chemical reactivity and are the most stable elements because they have maximum number of valence electrons.

They rarely reacts with other elements because they are already stable.

 They are odourless,colourless and

 can conduct electricity.

Examples of Noble gases are helium, argon,neon, Krypton,xedon,and radon.

COMPOUNDS.

  A compound is a substance which is formed when two or more elements are chemically combined together.

When a compound is formed,it is a new substance with properties entirely different from those of the components elements combined together to form the compound.

For example, the properties of water,a compound which is formed from the combination of Hydrogen and Oxygen,is entirely different from that of Hydrogen and Oxygen.

Examples of compounds are water,sand, caustic soda, Ethanol, sugar,salt, limestone,etc.

MIXTURES.

This is a substance formed by the physical combination of two or more components (elements and/or compounds),which can easily be separated by physical methods.

 

No chemical change is involved in the formation of mixtures and the proportions of each components in a particular mixture varies. 

   TYPES OF MIXTURES.

1.Homogenous mixtures.

  These are mixtures that are uniform in composition throughout any of it's given sample in which the components cannot be distinguished from one another.

 Examples are alloys,salt and water mixture,

Cement,air,powder,milk, bitumen, plastics,blood plasma,wine,wood,etc.

2.Heterogenous mixtures.

  An heterogeneous mixture is a substance in which the components parts can be differentiated from one another,ie,we can easily identify the components that combined together to form it.

Examples are the mixture of sand and water,concrete formed by combining cement and water,sugar and sand mixture, salt and pepper mixture,etc.

DIFFERENCES BETWEEN MIXTURES AND COMPOUNDS.

1.Mixtures can be homogeneous or heterogeneous while compounds are always homogeneous.

2.The constituents in mixtures can easily be separated by physical method because they're not chemically combined while in compounds,the components are chemically combined together and cannot be separated by physical means.

3.The components in a mixture are not fixed in quantity,so they can't be represented by a chemical formula,while in compounds,the quantity of each elements combined together are in fixed ratio to one another,no matter the mass, therefore,a compound can be represented by a chemical formula.

For example,The ratio of Hydrogen to Oxygen in water is always 2:1,in every quantity of water.

4.The properties of a mixture are the sum of those of it's components,while in compounds,the properties of each individual components elements are entirely different from that of the compound formed.

5.No new substance is formed in mixtures but new substances are formed in compounds.

6.Mixtures have variable melting and boiling point while compounds have fixed melting and boiling point.

7.In the formation of mixtures, there's no loss of heat and energy while in compounds, there's loss of heat and energy when they 

are formed.

See kinetic theory of matter ✏️