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Formulas of acid and base

Formulas of acid and base


 List the formulas of  acid and base

Hello friends, welcome to blog, today we are going to discuss and list the formula's of acid and base.
The earlier classification of substances into acid and base according to their characteristics and properties. For example an acid is a substance  with the sour taste and turns blue Litmus to red also liberate hydrogen with active metal like sodium, potassium, calcium etc.
A base is a substance with the bitter taste and turns red litmus to blue and have a soap touch.For example NaOH , KOH etc.


Various theories and modern concept explain acid and base are based on the structure and composition. Three theories concept's explain the acidic and basic character of a substance. These are Arrhenius concept, bronsted lowry concept and Lewis concept.

These theories helps to identify  a substance whether it is a strong or weak acid / base.

In 1884 an Arrhenius  proposed the theory of acid and base. According to this,

Acids

  Acids are substances which produce(dissociates) hydrogen ion(H+) when mixed with water.It has its own chemical properties and characteristics when react others.
For example:-
                       

Base

  Base are substances which produce(dissociates) hydroxide ion(OH-) when mixed with water.
Note:-
 While studying remember "properties of Acids and Bases" all bases do not dissolve in water. An alkali is a base that dissolves in water. Common alkali's are NaOH Sodium hydroxide KOH Potassium hydroxide
For example:-
 

what is the formula for hydrofluoric acid- HF
phosphorous acid formula-H3PO4
hydrobromic acid formula-HBr


Properties of acids and bases

Properties of acids and bases

Properties of acids and bases

Properties of acids and bases: The classification of substances into acid and base is according to some of their characteristics.

how can you tell an acid from a base

We can classify properties of acid and base
1.Physical methods
2.Chemical methods

Physical Properties Acids and Bases

The substances that taste sour are called as acid. For example lemon juice, tomato, curd.
The substances that taste bitter are called as base.For example soap, lime water containing calcium hydroxide, house cleaners.

Some Naturally occurring acids

 Vinegar                     – Acetic Acid
 Orange                      – Citric Acid
 Lemon                      – Citric Acid
 Tamarind                  – Tartaric Acid
 Tomato                      – Oxalic Acid
 Sour milk (Curd)       – Lactic Acid
 Ant and Nettle sting          – Methanoic Acid

Acid-Base Indicators

             Name of the                             Colour Change                             Colour Change
                Indicator                                   withAcid                                        with Base


A.      Blue litmus solution                          To red                                          No change
B.      Red litmus solution                            No change                                   To blue
C.      Turmeric                                             No change                                   To red
D.      Methyl orange                                    To red                                          To yellow
E.      Phenolphthalein (colourless)               No change                                  To pink

Chemical Properties of Acids and Bases

1. Acid + Metal → Salt + Hydrogen

Pop test : When a burning candle is brought near a test tube containing hydrogen gas it burns with a ‘Pop’ sound. This test is conducted for examining the presence of hydrogen gas.

2. Base + Metal→ Salt + Hydrogen
      Note – Such reactions are not possible with all the metals.


3. Action of Acids with metal Carbonates and metal bicarbonates

Metal Carbonate + Acid → Salt + Carbondioxide + Water

4. Acids or bases in a Water Solution

   Acids produce H+ions in the presence of water
   Bases provide (OH–) ions in the presence of water

5. Reaction of Non Metallic Oxide with Base
   
     Non metallic oxide + Base →  Salt + Water

6.Reactions of metal oxides with acids

   Metal Oxide + Acid → Salt + Water

7. Neutralization Reactions 

     Base + Acid→ Salt + Water
Note:-
 While studying remember "properties of Acids and Bases" all bases do not dissolve in water. An alkali is a base that dissolves in water. Common alkali's are NaOH Sodium hydroxide KOH Potassium hydroxide












Chemistry Bond order|bond strength order|all Examples.

Chemistry Bond order|bond strength order|all Examples.

Bond order

Hello friends, welcome to our blog,today we are going to discuss the bond order, how to calculate it and what's its formula. The bond order can be calculated with the help of two concepts.
1. Lewis concept and
2. Molecular orbital theory(MOT)

According to Lewis concept , in a covalent bond, the bond order may be defined as:

 The number of bonds between the two atoms in a molecule. 

For example,

Bond order of H2(H−H bond) = 1           ;                  Bond order of O2 (O=O bond) = 2
Bond order of N2(N≡N bond)  =3            ;                 Bond order of (H−C≡C−H)
                                                                                                 carbon-carbon bond order= 3.
Note:

1.The Isoelectronic molecules and ions have identical bond orders
    For example, bond order of  N2 , CO and NO+  (all have 14 electrons) is 3.        

2. With the increasing bond order, the bond enthalpy increases and bond level decreases. For example,
 Bond order of N2 =3;Bond enthalpy = 945 KJ mol-1       
Bond order of O2 = 2;Bond enthalpy = 498 KJ mol-1     
Bond order of F2 =1;Bond enthalpy =  158 KJ mol-1
This video helps you how to write electronic configuration using MOT concept.
In case of Molecular orbital theory, the electron present in bonding molecular orbital is known as bonding electrons while electron present in antibonding molecular orbital is called antibonding electrons.
                

 Also, we have learnt that bonding molecular orbitals have lower energy as compared to antibonding molecular orbitals and greater stability. Thus, the molecular orbital stability  can be predicted in terms of electrons present in bonding molecular orbital( Na electrons)and those present in antibonding molecular( Nb electrons).The following generalisation can be made.

Stability

A. If Nb > Na ,the molecule is stable.
B. If Nb < Na ,the molecule is unstable.
C. If Nb = Na ,the molecule is unstable.

In fact, the bonding electrons tend to bring nuclei of the atomic orbital closer while the antibonding electrons tend to  push them apart. Thus, a stable  molecule will be formed only if Nb  electrons are more than Nelectrons.

Bond order Define

Half  of the difference between the number of electrons present in bonding and antibonding molecular orbitals.

Bond order formula

Thus,Bond order(B.O)=1/2[Nb -Na ] 
The Bond order may be whole number,fractional or even zero..It may also be positive or negative.    
If Bond Order = Positive, the molecule is stable.
If Bond Order = zero, the molecule is unstable or not exists.   
If Bond Order = Negative, the molecule is unstable.               

Hydrogen molecule(H2 )    

Molecular orbital electronic configuration of H2 =[ s1s ]2  [ s1s* ]0
Bond Order :-1/2[Nb -Na] = 1/2[ 2 -0 ] = 1    
Positive value indicate =stable
It is diamagnetic in nature since the only occupied molecular orbital filled.

Hydrogen molecule ion(H2 +

Total no. of electrons = 1
Molecular orbital electronic configuration of H2 + =[ s1s ]1  [ s1s* ]0
Bond Order :-1/2[Nb -Na] = 1/2[ 1 -0 ] = 1/2
An unpaired electron always indicates that the molecule is paramagnetic.

He2+ molecule ion, 

Total no. of electrons = 3,
Molecular orbital electronic configuration of He2+  cation =[ s1s ]2  [ s1s* ]1
Bond Order :-1/2[Nb -Na] =1/2[ 2 -1 ] = 1/2
Unpaired electron, so paramagnetic.












How do Molecules Bond|Chemical Bond Form

How do Molecules Bond|Chemical Bond Form

How do Molecules Bond

Hello friends, welcome to our blog, today we are going to discuss formation of molecule on the basis of the valence bond theory(VBT).This theory  based on the concept of atomic orbital and also the orbital configuration of atoms.Whenever word chemical bond to hear bond it means tie something together and chemical means that is irreversible by physical means. Lets explain the formation of hydrogen(molecule) as an example. When the hydrogen atom combine to form molecule of hydrogen, energy is released. This shows that the energy of hydrogen molecule is less than as compared to the hydrogen atom.
In general, whenever atom combined to form molecule there is always decrease in the energy which leads to increase the stability. Actually, when atoms of are far separated,they do not have any force of interaction(attraction or repulsion).As they come closest that different forces operate.

1.The nucleus of one atom is attracted towards the electrons of other end and vice versa. Energy is released in a attraction.

2. The nucleus of atom as well as the electrons repel each other.Energy is needed to overcome the force of repulsion.


Formation of hydrogen(H2) molecule


If the magnitude of attractive forces is more than the repulsive forces, then stable molecule will be formed. However if the repulsive forces are more than attractive forces, then the atoms will not combine with each other.

 In the light of above discussion, let us consider the combination between the atoms of hydrogen Ha
and Hb .if Eand Eb are the respective electrons, then the attraction and the force of repulsion may be shown as

Although the number of new attractive and repulsive forces is the same, but the magnitude of attractive forces is more. Thus, when two hydrogen atoms approach each other the overall potential energy of system decreases. Therefore, a stable molecules of hydrogen gets formed.

The potential energy changes which takes place in the formation of hydrogen molecule may be also shown graphically as follow

When the two hydrogen atoms are far separated (at infinite distance) the potential energy is zero. As they start coming closer to each other from infinite distance, energy lost correspondingly. Ultimately, a point of minimum energy is attained when the attractive and repulsive forces are balance each other. At this stage, the hydrogen atoms are bonded together to form a molecule of hydrogen. The distance between the centre of the their nuclear is called bond length.
In case of hydrogen molecule, H-H bond is74 pm. It may be kept in mind start that  two hydrogen atom cannot be brought closer then 74pm.

If it happens then the repulsive forces become more than attractive forces. As a result, potential energy will increase as shown by line. The total decrease in the potential energy when one mole of bond of particular type are formed between the atoms in gaseous state is called bond energy. For example the bond energy of hydrogen hydrogen is 433 kilo joule per mole. It may be noted that the same energy is needed to break the molecules into the atoms is known as bond dissociation energy Thus,bond dissociation energy of hydrogen is also 433 kilo joule per mole.
How did Ernest Rutherford discover the nucleus|Rutherford Model of atom

How did Ernest Rutherford discover the nucleus|Rutherford Model of atom


How did Ernest Rutherford discover the nucleus

Hello friends,  welcome to our blog, today we are going to discuss how did Sir Rutherford discovered the nucleus. In 1911, Rutherford performed alpha
(α) ray scattering experiment to know about the position of fundamental particles electron, proton in an atom. The alpha(α) particles were obtained form the radioactive element radium enclosed in the box of lead. After passing through a slit, the particles in the form of rays were made to strike against the very thin foil(4*10-5 cm thick) of heavy metal like gold. These particle got scattered and were made to fall on circular screen coated with zinc sulphide(ZnS). They produce flashes of light (also known as scintillation) on screen this help in identifying these particles.

From the experiment, Rutherford made the following observations

1. Most of the alpha particles (99%) passed through gold foil undeflected.

2. Some of these particles be deflected by small angles.

3. A very few alpha particles (one out of 20,000 particles) suffered major deflections by more than 90° and even came back in same direction.

Conclusion from the observation 

The scattering experiment was performed on the gold foil consisting of atoms of gold closely packed in a space and arranged in layers. Rutherford was of the opinion that
most of the alpha particles passed through atom of gold.This means that did not come across any path interrupt.

1. Most of the space inside the atom is expected to be empty. The electrons are negligible mass was supposed be present in this space.
2. As a few of alpha particles suffered from minor deflections and are very few even major deflections, this means that they must have come across some obstruction in their path which must be very small(nucleus contains charge that repel positive charge alpha particle).

Rutherford regarded this(nucleus) small, heavy and positively charged portion inside the atom as a nucleus.All the positive charge protons was supposed to be present in the nucleus and they also accounted for its mass.Some of the space around the nucleus is called extra nuclear portion and all the electrons were supposed to be present in it.


 Rutherford further stated the electron present in extra nuclear portion did not offer any objection to alpha particles and therefore most of them could pass undeflected.

Rutherford Model of atom

In the light of alpha Ray scattering experiment, Rutherford gave the following picture of an atom.

1. An atom consists of two parts nucleus and extra nuclear portion

2.Nucleus is present in the centre of atom. It is massive positively charged also extremely small in size. The radius of nucleus is about 10-15 m. while the atom is about 10-10 m. The size of nucleus is very small as compared to that of atom.

3. Positive charge of the nucleus is due to protons in the atoms. Since the atoms differ in  number of protons therefore,  the magnitude of positive charge on nucleus differ from atom to atom.

4. Extra nuclear portion is a space around the nucleus in which all the electrons are present.

5. Total positive charge of the nucleus is equal to the total net charge of  electrons and the atom as a whole electrically neutral.

6. Electrons in the extra nuclear portion are not stationery but are revolving around the nucleus at a very highest speed in a circular path called orbits. The revolving electrons have certain centrifugal force acting away from the nucleus which balance  the force of attraction directed towards nucleus.

The model of an atom is similar to the solar system where the nucleus is like a sun and electrons may be compared to the planets. The electrons are therefore, called as planetary electrons.
Covalent bond With Examples

Covalent bond With Examples

                   Covalent bond

Hello friends, welcome to our blog, today we are going to discuss the covalent bond. We know that bond means two or more things tie together.Bond may be of different types.

Electrons in a covalent bond

In the formation of molecule only the electrons present in outermost shell or valence shell of atoms normally participate while the electron belongs to inner energy shell are mostly not involved in the bond formation.

Remember: A bond will form only when combining atoms have minimum energy and maximum stability.This will possible if the atom complete the octet (8 electrons in outermost shell) and achieve the electronic configuration of nearest noble gas atom.

In  covalent bond the combining atoms mutually contribute one, two or three electrons depending upon their requirement the bond formed.This leads the formation of single double and triple bond.

Covalent nond is generally present in the atoms of non metal. This may be either same or different. In case of atoms are same the covalent molecule is known as homoatomic and if the combining atoms are different then it is called as heteroatomic molecules

Homoatomic molecules(non polar covalent): The simplest among them is hydrogen Hmolecule in which both the participating atoms have one electron each initially, share there electron and both achieve the stable electronic configuration.

Another example:Chlorine molecule  Cl2 .In this case both the chlorine atoms that is equals to (atomic no 17) have 7 valance electron and a short of one electron each.They share one electron pair which is an electron is contributed by both the atoms to achieve nearest noble gas configuration.


The electron pair belonging to individual atoms not involving sharing called as lone pair (example:oxygen molecule).

Homoatomic molecules(polar covalent): In this case the atom taking part in bond formation belongs to different elements. A few examples of heteroatomic molecules are:
 



It should be noted that this the structure of  molecules or ions in which shared electrons are represented by the dots are known as Lewis dot structure. While those in which these are indicated by line or dashed are called as Couper structures.

How do ionic bonds form|With Examples|Factor Influencing

How do ionic bonds form|With Examples|Factor Influencing

Ionic bond

Hello friends, welcome to our blog. Today we are going to discuss ionic bond. An ionic bond is also called as electrovalent bond.

How do ionic bonds form

In the formation of molecules only electrons present in outermost shell or valence shell of atom normally participate while the electrons belonging to inner energy shell are mostly not involved in the formation of bond.

An ionic bond is formed when there is complete the transfer of one or more electrons from one atom to another.

Bond between metal and nonmetal

 It is generally formed between the metals and non-metals.The metal atom loses one or more electrons present in its valence shell and these electrons are taken up by the non-metallic atom.

Since, the atoms are electrically neutral (electrons and proton are equal in number),by losing electrons,the metal atom changes to positive ion or cation.Similarly, the non-metal atom gaining the electrons, get converted to negative Ion or anion. The opposite charged ions are attracted towards each other and therefore,  come closer resulting the formation of ionic bond (electrovalent Bond).Thus, ionic or electrovalent bond may be defined as :

Definition

 The coulombic or electrostatic force of attraction which hold the opposite charged ions together.

NaCl bond

Formation of sodium chloride (NACl). Sodium atom (Z=11) has one valence electron(2, 8, 1). Similarly chlorine atom (Z=17) has a 7 valance electron (2,8,7). Sodium atom loses its only valence electron and changes  Na+ ion(cation). This electron is taken up by chlorine atom which changes to a Cl- ion(anion).Both of these ions are mutually attracted to form NaCl molecule.


Na +  ion has the configuration of Ne while Cl- ion represent configuration of Ar. Both are inert gas atoms.These the atoms take part in chemical combination or bond formation in order to complete the octet( 8 electron in valance shell) and achieve the electronic configuration of nearest noble gas atom.

Formation of calcium fluoride(CaF2 ).Calcium atom (Z=20) has two valence electron (2,8,8,2). while fluorine atom (Z=9) has seven valence electron in its valence shell (2,7).Now,Ca atom wants to get rid of both valence electrons but each fluorine atom is in position to take up one electron only, This means that these electrons are accepted by two fluorine atoms as shown below.



Ca 2 + ion has electronic configuration of inert gas argon while F- ion has the electronic configuration of neon.

Electrovalency:

It is defined as the number of electrons which an atom lose or gain in the formation of ionic bond.

Actually, electrovalency of an atom is in number of unit charges(positive or negative) on the ion in an ionic bond. If the unit charges are positive, electrovalency is positive. Similarly, electrovalency is negative in case these are the negative. for example in CaF2 electrovalency of calcium is 2(positive) and the fluorine is 1 (negative)

Factor influencing the ionic bond formation

We have learnt that in bond formation one atom loses one or more electrons while the other accept them. As a result cation and anion formed .They mutually attracted by the electrostatic force of attraction result the formation of ionic bond. According to Kossel's scientist ionic bond depends upon the following factors:

Ionization enthalpy

 The amount of energy required to remove the loosely bound electron from an atom is called ionization enthalpy.

 Lesser the ionization enthalpy required easy form of cation.The alkali metals and alkaline earth metals present in s- block normally form cation since they have comparatively low ionization enthalpy.

Electron gain enthalpy

The electron released  in the formation of cation are to be accepted by the other atoms taking part in the ionic bond formation.The electron accepting tendency of an atom depends upon electron gain enthalpy. It may be defined as:
 energy released when an isolated (gaseous) atom take up electron to form anion.

Greater the negative electron gain enthalpy , easier will be the formation of anion. The Halogen present in group 17 have the maximum tendency to form anions as they have very high negative electron gain enthalpy.
The members of group 16 oxygen family such as Oxygen also forms in anion. It has lesser negative electron gain enthalpy then group 17 because it has lesser tendency to form anion.

Lattice energy or enthalpy

The ionic compound exist as crystalline solid and arrangement is called as crystal lattice. Since the ions of charged species, energy (known as lattice energy) is released in the attraction of ions so it may define as:

Energy released when 1 mole of crystalline solid is formed by the combination of oppositely charged ions.

 Greater the magnitude of lattice energy more will be the stability of ionic bond. Ionic compounds

the lattice energy depends upon the following factors:

Size of ion:- The size of ion influence the lattice energy. Smallest size lesser will be the internuclear distance and thus, greater will be the lattice energy. For example: lattice energy of NaCl is more than KCL because the radius of Na + is smaller as compared to K+ ion.

Charge on the ion:-Greater the magnitude of charge on ions higher will be the inter ionic attraction and thus,greater will be the higher value of lattice energy.

So, we conclude that if the magnitude of lattice energy and the negative electron gain enthalpy is greater than that of the ionization enthalpy required, a stable chemical bond will be formed in case it is less than the bond will not form.

General characteristics of ionic bond

1. Melting and boiling point: Because of strong inter ionic forces the ionic compound have generally high melting and boiling point.

2.Solubility: Ionic compounds generally dissolve in polar solvent (like water). Actually in such solvent the polar(water) molecule interact with the ions of crystalline solid(NaCl salt) energy is released. Then the energy released is known as hydration energy and the energy released overcome(weakened) electrostatic force between ions thus get separated and go into the solution. The ionic compound do not dissolve in organic solvent like Benzene carbon tetra chloride because they are non polar in nature.

3.Ionic reactions :The ionic compound the reacts each other through ions which are formed in the solution. Therefore,these take part in ionic reaction which are very fast and do not required any specific condition. For example aqueous solution of NaCl and AgNO3 are mixed a white precipitate of AgCl is immediately formed.

Metallic Bond and types|A metallic bond is a bond between

Metallic Bond and types|A metallic bond is a bond between

Metallic Bond

Hello friends, welcome to our blog, today we are going to discuss metallic bond. Most metal crystallize in close- packet structures. Strong electron interaction among 8 to 12 nearest neighbour atoms (called as coordination number) develop the ability in metals to conduct electricity and heat.


A metallic bond is a bond between

 Bonding in metals is called as metallic bonding. Bonding in metals result from electrical attraction among  positive charge metal ions and mobile, delocalised electrons belonging to Crystal as a whole.

Two models are considered to explain metallic bonding:

1.Band model
2.Electron Sea model

Band Model.

The interaction of two atomic orbitals, say 3s- orbitals of  two sodium atoms,produces two molecular orbitals, one bonding orbitals and one antibonding orbitals .If N atomic orbitals interact , N molecular orbitals are formed. Atoms interact more strongly with nearby atoms than those of farther away. The energy that separates bonding and antibonding molecular orbitals decreases as the interaction (overlap) between the atomic orbital decreases. When we consider all the possible interactions among one mole of  Na atoms, there is a formation of series of very close spaced molecular orbitals(3σ s and 3σ*s (sigma star)). This consists of nearly continuous band of orbitals belonging to crystal as a whole. One mole of Na atoms contributes one mole(6.022×10 23 )of Valence Electrons thus,6.022×10 23 orbitals in the band are half filled.

The empty 3p  atomic orbitals of sodium atoms also interact to form a wide band of 
3* 6.0710 23  orbitals.The 3s and 3p atomic orbitals are quite close in energy, so that these bands of a molecular orbital overlap. The two overlapping band contains 4 *6.0710 23 orbitals. Because each orbital can hold two electrons, the resulting  combination of full bands is only one eighth full.


According to the band theory, the highest energy electrons of metallic crystals occupy  either fully band or partially band that overlap an empty band. A band within which(or into which) electrons must move to allow electrical conduction is called conduction band. The electrical conductivity of metal decreases as temperature increases. The increase in temperature causes  thermal agitation of metal ions.This impends the flow of electrons when an electric field is applied.
Crystalline nonmetals ,such as diamond and phosphorus are insulators, they do not conduct electricity if it is due to the fact that their is highest energy electrons occupy filled bands of molecular orbitals that are separated from the lowest empty band (conduction band) by the energy difference called the band gap.In insulated ,this band  is in an energy different that is too large for him to jump to get the conduction band.


Elements that are semiconductors have filled  bands that are only slightly below, but do not overlap with empty band.They do not conduct electricity at low temperature but small increase in temperature sufficient to excite some of the electron and jump into the highest energy band conduction band.

Electron Sea model

Metals have ability to conduct electricity, ability to conduct heat, formation into sheet drawn, into wires and lustrous appearance. One over simplified model that can account for some of the properties is electron sea model. The metals picture as a network of positive ions immersed in a "sea of electrons". In Lithium  the ions would be Li+ and one electron per atom would be contributed to sea. These free electrons account for the characteristic meal properties. If metals ends are connected to the external source of electric current, one end free electron cross through metal and leave the other end at the same rate in thermal conductivity in electron .

By hammering the internal structure remain unchanged as a sea of electrons rapidly adjust to new situation.

Characteristics of Bond |Bond Length|Bond Enthalpy|Bond Angles

Characteristics of Bond |Bond Length|Bond Enthalpy|Bond Angles

Bond Characteristics

Hello friends welcome to our blog, Today we are going to discuss the various bond characteristics.we know that the chemical bond is possible only if atoms will acquire minimum energy and maximum stability. If it is not having minimum energy than the bond will be very much unstable.

Bond length 

Bond length may be defined as:
                 The average equilibrium distance between the centres of two bonded atoms.

It is also called as Bond distance. The bond length of different covalent bonds are determined by X-Ray diffraction methods.
For covalent bond, It is sum of covalent radii of bonding atoms.For example, Bond length of C-CL bond is cl +  c.
The value of Bond length is expressed in picometre(1 pm=10  -12metre). The various factors such as resonance, electronegativity,hybridization,steric effect etc influence the bond length.

Factor Effect Bond length

1. Size of atoms. The bond length is directly linked with the size of bonding atoms.The bond length of Polar bond is smaller than non polar bond length. For example H-Br bond length(141 pm) is more than H-Cl Bond (127 pm)

2.Multiplicity of bond. The length of double bond(C=C) is less than the length of single bond(C-C) between the same atoms(homo atomic) and the triple bonds(C≡C) even shorter than double bond .

Triple Bond<Double Bond<Single Bond

C≡C            <   C=C               <    C-C

The Multiplicity of the bonds between two atoms brings them close to each other. As a result, the bond length decreases. For example, bond length of C-C bond is 154 pm and the value of C=C bond is 134 pm.

3.Type of hybridisation. The value of  bond length is also influenced by the type of  hybridization.Since s orbital is smaller in size as compared to p orbital,Therefore,greater the s- character smaller will be the bond length.
Example: The alkanes (C-C) have 25% of s character.33.3%  s character  in alkenes(C=C) and
50% as character in alkynes (C≡C).
                   


4.The bond length of same type of two atoms diatomic molecules are twice the covalent radius.

Bond length table

                     Bond Length of Some Common Bonds








Bond Enthalpy

When atoms combine to form bond a certain amount of energy is released.Same amount of energy is needed to break Bond into atoms.Bond enthalpy or bond energy may be defined as

the amount of energy required to break one mole of bond of a particular type in between the atoms in gaseous state of a substance.

Factor Effect Bond Enthalpy

1.The magnitude of bond energy depends upon the type of bonding. Most of the covalent bonds have energy between 50 to 100 kcal per mole.The strength of sigma bond is more than than that of pi bond.

2. If a molecule contains more than one bond of same type, then their bond enthalpy are not same because of the presence of different neighbouring atoms. In such cases, bond enthalpy is the average of bond enthapies of all these bonds.
For example, Cl-Cl Bond enthalpy is 239 kJ per mole while H-H  bond is 433 kJ per mole.

3.If a diatomic molecule contains triple C≡C bond,then it has higher bond energy than that of double bond.Similarly,double bond carbon atoms has higher bond enthalpy than single Bond between the same atoms.

Order

C≡C           >   C=C             >    C-C

4. The bond energy is depend upon the bond length.Shorter the bond length higher is the bond energy

5. The bond energy decreases with the increase in lone pair(lp) on bonded atoms.Electrostatic repulsion of lone pair electrons with  the bonded atoms.

Lp-Lp>Lp-Bp>Bp-Bp

6.Bond energy is also affected by the resonance structured.
Resonance structure. It is a phenomenon of which a molecule expressed in different forms none of which can explain all the properties of molecules.

7.In case of similar molecules bond energy decreases down the group

8. In hybridization the order of energy is

Sp3>sp2>sp>p>s


C H bond energy

The bond dissociation energy of all C-H bonds in methane is not same. Actually when one C-H bond breaks away the electron environment for the remaining C-H Bond change. The carbon atom is now linked with the three C-H bond and not four. Therefore bond dissociation energy changes.

CO bond Energy

The carbon oxygen bond is strongly polarized towards oxygen beacuse  oxygen has much higher electronegative value  than that of carbon.Therefore, the bond length between carbon and oxygen shortens and hence cause the greater bond energy.Bond energy is increasing when going from single to double(CO2) to triple bond(CO)

Bond Angles

Angle between the two adjacent bond of an atom in a molecule made up of three or more atoms is known as bond angle. Bond angle mainly depends upon three factors.

1.Electronegativity. If the central atom is not high electronegative then, bond angle decreases.


2.lone pair repulsive.Lone pair plays a major role in changing the bond angle. If central atom is having lone pair of electrons then the central atom lone pair try to repel the share pair(bonded atoms) of electrons.This is how bonds are slightly displaced inside result in a decrease of bond angle.

3.Hybridization. Bond angle depends upon the state of hybridisation. If the central atom S character increases the hybrid Bond the bond angle increases.


Chemistry Chemical Bond|Types of bonds chemistry

Chemistry Chemical Bond|Types of bonds chemistry


Chemical Bond

Hello friends welcome to blog, Today we are going to discuss chemical bonding.Whenever word bond to hear it means  tie something together and chemical means that is irreversible by physical means.

                       


How are Chemical Bond Form and Defination


Normally,if atom does not complete its valance shell we call  atom is does not exist independently,To exist independently chemical Bond are formed by a force that hold together the different atoms in a molecule is called as chemical bond and number of valence electron(outermost electrons in a shell) participate decide the shape structure and characteristics of a molecule.

Atoms Form Bond To 

Atoms combine to form bond to achieve minimum energy and maximum stability. These are the two key factors that tells why atoms combine to form chemical bond.If atom does not have minimum energy then it will never have stability so bond is not possible.

How do Bond Form

Bond form with stability.Stability means atoms of different elements take part in chemical bond or bond formation in order to complete the octet (outermost shell)and have the electronic configuration of nearest noble gas atoms

Remember

The stability of noble gas elements is due to the presence of 8 electrons in the valence shell(except Helium has duplet) or due to the presence of complete octet.


How do Molecules Bond(Chemical Bond Form)

In the formation of molecule bond only the electrons present in outermost energy shell (valence shell of atom) normally participate while the electrons belong to inner  energy shell are mostly not involved in the Bond formation.we all know that except noble gas elements, the atoms of no other element exist independently. However, a group of atoms known as molecules have independent existence. The formation of chemical bond a molecule will only be formed if it is more stable and has lower energy then individual atoms.. Lewis introduced symbol to represent the valence electrons in the atoms. these are called as lewis symbol in which valence electrons are shown as dotted surrounding the symbol of an atom for example the symbol of carbon  is C while is symbol is

In the light of octet rule, Lewis and kossel have electronic theory of chemical bonding to represent dot structure.




Types of Chemical Bonding(Bond Types)

While talking about this chemical bonding.This question arises itself.

A.By Electron Transfer:- 

                  There is a transference of one or more electrons from one atom to other and the bond         formed is known as ionic or electrovalent bond.

B. By Electron Sharing :-

                  In this case combining atoms mutually contribute one.two,three electrons depending upon their requirement the bond formed is called as covalent bond.


C. Dative Bond:-



                    In some cases only one of the bonding atom contribute the electron pair while sharing is done by both called as co-ordinate Bond or dative Bond.

In addition to these in types of chemical bonding, the atoms of metal linked by metallic bond while inter molecular force of attraction arise hydrogen bonding and Van der waal forces for the formation of covalent bond.

The kind of force in chemical bonding decide the physical state, melting and boiling point, electric conductivity, solubility  and other factor influencing the formation of Chemical Bond.


Fact stated by Kossel in relation to chemical bonding

1. In a Periodic Table the higher electronegative element halogen (group number 17) and higher electropositive alkali metal (group number 1) are separated by a noble gas elements  placed on the extreme right in the periodic table .

2. The atoms of elements belongs to halogen family change to negative ion or anion by gain an electron. Similarly,alkali metals family change the positive a cation by lose an electron.

3.Both positive and negative ion acquire noble gas configuration i.e the achieved stable octet by completing its outermost shell

4. The negative and positive is  stabilized by the electrostatic force of attraction which is the experience.

Strongest chemical bond

Strong chemical bonds are the intramolecular forces which hold atoms together in molecules.Strongest chemical bond is sigma bond or Triple bond.