: Structure of an atom and much more Submitted By:-
Deepak Saxena of Class ixth ‘B’ Session : 2010-2011 People’s Public School Contents : Contents Atom
Neutrons (N0 )
5.1 J.J Thomson Modal of ATOM
5.2 Rutherford’s Modal of ATOM
5.3 Bohr’s Modal of ATOM
6. Thanks Atoms : Atoms Atom : Atom “Atoms are said to be the very tiny particles of any matter that cannot be divided any more after a certain stage “ for example :
Take a chair and keep on doing its pieces , a stage will come when there will small particle left that particle can be said to be an atom. Particles in atom : Particles in atom According to today's chemistry I know that atom has 3 types of particles and they are :
Neutron Electron’s (e-) : Electron’s (e-) “Particles with negative charges on them are said to be as Electron’s “ . Proton’s (p+) : Proton’s (p+) “Particles in atom with positive charge on them are known as Proton’s “ . Neutron’s (n0 ) : Neutron’s (n0 ) “The that do not have neither positive nor negative charge on them are named as Neutron’s .” Comparative table : : Comparative table : Finding of Proton’s, Electron’s & Neutron’s : Finding of Proton’s, Electron’s & Neutron’s There is very simple way to find that an atom contains how many Protons , Electrons , & Neutrons in it .
The only thing that we need to know is the atomic number of that atom as well as the mass number of that atom Atomic no. & Mass no. : Atomic no. & Mass no. As we all know that there are 114 known elements. So to be in an comfortable manner scientists made up the table called “ Periodic Table”. This table consist of all the elements that are founded till the date. Mass no. : Mass no. As we make it from the name that I must be talking about the mass of the atom taken. The mass is nothing but the sum of electrons Protons & neutrons . But actually mass no. can be finded through just doubling the atomic no. of the given atom if the atomic no. is even .
If the atomic no. is odd then just double the atomic no. and add 1 to the answer . Representation of atomic no. and mass no. : Representation of atomic no. and mass no. Atomic no. is denoted with ‘X’ , mass no with ‘A’ and atomic no. with say ‘Z’.
Atomic no. is written in downward and mass no. is written in upward form.
Mass no. = A
X= symbol of element
Atomic no.=z Finding Proton & electron : Finding Proton & electron Now if we know the atomic no. then we can find both of the proton & electron.
Because the no. of protons and electrons are directly proportional to the atomic no. for example :
We take sodium . The atomic no. of Sodium (Na) is 11 therefore the :-
Atomic no. = no. of Protons = no. of Electrons Finding of neutrons : Finding of neutrons There is very easy and simple way to find neutrons as we had earlier taken sodium (Na) so the formulae for finding neutrons is :-
Mass no. – Atomic no. = no. of neutrons Modals by scientists : Modals by scientists J.J Thomson Sir Rutherford Neil’s Bohr JJ Thomson modal for atom : JJ Thomson modal for atom The first person to suggest a modal for atom was the sir J.J Thomson .
He assumed that atom is a sphere filled with the positive charges with the electrons (e-)
His modal looked like a cake. Saying’s by Thomson : Saying’s by Thomson An atom consist of positive sphere and electrons in it .
The negative & positive charges balance each other .
Atom as a whole can be said to be neutral. Rutherford’s Modal of an ATOM : Rutherford’s Modal of an ATOM Rutherford made the experiment for the study of atom.
He made the alpha particles pass through the atom and observed it.
He found that some of the rays are reflected. He observed that there are some particles inside the atom. He found that he could answer some of the doubts due to Thomson’s modal Observations by sir Rutherford : Observations by sir Rutherford Nucleus of an atom is positively charged.
Nucleus of an atom is very dense, hard, and rigid .
Nucleus of an atom is very small as compared to the size of atom (10-9 nm) as a whole. Bohr’s modal for ATOM : Bohr proposed that :
Electrons revolve around nucleus on fixed circular paths known as shells .
An electron has fixed energy .
The shells are called energy levels represented by K,L,M,N or 1,2,3,4. Bohr’s modal for ATOM Conclusion : Conclusion During my project report I have seen that how was atom defined and have learnt about its structure .
That the atom has 3 particles inside it , it has 4 shells that can be written in K,L,M,N format. Slide 27: THANKS FOR BEING PATIENT