Gram Molecular Mass

Gram Molecular Mass

The Molecular Mass of a Molecular substance expressed in grams is known as  Gram Molecular Mass .

It is also known as Gram Molecular Mass or gram atom or simply moles of substances.

 Formula

No of grams of molecular substance = Mass of molecular substance/Molecular mass of the substances

For example

• 1 gram molecules (moles ) of Hydrogen (H) = 2.016g of Hydrogen = 1 moles of Hydrogen molecules

• 1 gram molecules (moles ) of Carbon dioxide (CO₂) = 44.006g of Carbon dioxide  = 1 moles of Carbon dioxide molecules

•  1 gram molecules (moles ) of Nitric Acid (HNO₃) = 63.006g of Nitric Acid  = 1 moles of Nitric Acid  molecules

A moles of every  compound has 6.02x10^-23 molecules.

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Gram atomic mass (Gram atom)

Gram atomic mass (gram atom)

The atomic mass of an element expressed in grams is called gram atomic mass. I s is known as gram atom or simply  mole.

 Formula

So number of gram atom (moles) of an element = massof the element/atomic mass of the element

For example

•                       1 gram atom (moles )of Hydrogen (H) =1.008 0f hydrogen (H)

•                         1 gram atom (moles )of Nitrogen (N) =14 0f Nitrogen (N)

•                         1 gram atom (moles )of Calcium (Ca) =40.00 0f Calcium (Ca)

Reason

The reason is that atomic mass of hydrogen is 1.007µ, of nitrogen is 14.00µ and calcium is 40.00 µ . so  one moles of every element has 6.02x10^-23

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Moles

Moles

         It is the amount of a substance which contains the same number of chemical units as they are atom in excatly 12 grams of pure carbon -12
unit
its unit is mol.

For example
                   We say that two moles if water is 36 g . It is written as 36g of water =2mol.

Gram Atomic Mass
                               concept of moles are related with mass of substance .

1.  In the case of element we consider atomic mass.
2. In the case of covelent compound  we consider molecular mass.
3. In the case of ionic compound we consider formula  mass.

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Molecules

Molecules

A molecules is the smallest particles of a substance which has independent existence.it consist of a single or more similar or more different atoms.

Types

There are four types of molecules:

1. Monoatomic molecules
2. Homoatomic molecules
3. Hetroatomic molecules 
4. Polyoatomic molecules 

 Monoatomic molecules

                                      A molecules that contain single types of atom of the same elements is called Monoatomic molecules

For example
                    hydrogen, nitrogen etc.

Homoatomic molecules 
                                     When two or more of atom of the same elements combined to form a molecules then we call them homonuclear molecules 

For example
                    water, nitrogen, ozone etc.
            
Hetroatomic molecules
                     
                                      When two or more  atom of the different elements combined to form a molecules or hetroatomic molecules 

 For example
                     hydrogen Beomine, water, chloroform etc

Polyoatomic  molecules   
                                       
                                      A molecule having  two or more  atom of the different or same elements combined to form a molecules or polyatomic molecules 

For example
                   hydrogen, nitrogen etc.
                 

                                     

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Avogadro's number

Avogadro's number

                                Avogadro's number  number of units in one mole of any substance (defined as its molecular weight in grams), equal to 6.022140857 × 10²³. The units may be electrons, atoms or ions, or a molecules, depending on the nature of the substance and the character of the reaction . 

 

Significance 

  Avogadro's number is a proportion that relates molar mass on an atomic scale to physical mass on a human scale. Avogadro's number is defined as the number of elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is equal to 6.022×10²³ mol^-1.

Representation 

                         It is expressed as the symbol N_A.

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Molecular ion and Free Radical

 Molecular ion

                        Molecular species having positive or negative charge.Molecules is a neutral species and have  same number of electrons and protons.but in  Molecular ions number of electrons and proton are not same.

 

Free Radical

                    A free radical is an atom or ions or a molecules containing odd number of electrons .
 they are very reactive and short lifetimes because they reacts with other substance with which they come in contacts 

 

For example 

                    Methyl chloride 
                    Hydroxyl radical

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Chemical species

Chemical species 

 

Chemical species are atoms, molecules, molecular fragments, ions, 

 etc., being subjected to a chemical process or to a measurement. Generally, a chemical species can be defined as an ensemble of chemically identical molecular entities that can explore the same set of molecular energy levels on a defined time scale.

 

The  common chemical species are :

1.  Ions 
2. Molecular Ions
3. Free radical
4. Neutral molecules

Ions

      An atom or group of atom having positive or negative charge is called ion.

 

Positive Charge

                         When atoms lose one or more electron  positive ion are formed.

                                       

                                              A                                     A⁺   + Ie^-

                                              H                                     H⁺  +  Ie^-

^{Charge on cation depends upon the number of electrons lost.}

^{Negative charge} 

                          ^{When atom add one or more electrons , anion are formed.}

                                                  A   + Ie^-                       A^-

                                                  H  +  Ie^-                       H^-

 ^{Charge on cation depends upon the number of electrons added.}

                          

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