In Science, we study a topic called atom which is the smallest unit of ordinary matter that forms a chemical element that may be in solid, liquid & gas form.
Atomic structure refers to the structure of an atom containing a nucleus (at the center having major mass of the atom) in which there are protons (positively charged) and neutrons (neutral) and electrons (negatively charged) revolving around the nucleus.
The nucleus contains two types of subatomic particles together called nucleons. Protons and neutrons are the two types of nucleons.
Atomic model inventions: Inventor year of All atomic theory
Q. Who are the scientists who contributed to the atomic model?
Ans:- Below are the various atomic structure models invented during huge years of gaps to bring improvement into the previous atomic model proposed by the scientists for better explanation.
Scientists for atomic models:-
Dalton’s atomic theory:-
British scientist John Dalton put forth in 1803 A.D. his celebrated ‘Atomic Theory’. According to this theory, the matter is made of atoms and atoms are indivisible and indestructible. All atoms of an element are alike while different elements have different atoms with different masses.
The atom, as described by Dalton, turns out to be a hard, solid sphere with no internal structure.
According to Dalton’s atomic theory, the mass is distributed uniformly in an atom.
Thomson’s plum pudding model of the atom:-
As in the previous model, an atom is electrically neutral in spite of having negatively charged electrons in it. Thomson overcame this difficulty by putting forth the plum pudding model of atomic structure.
The plum pudding model of atom put forth by Thomson in the year 1904 is the first model of atomic structure. According to this model the positive charge is distributed throughout the atom and the negatively charged electron are embedded in it. The distributed positive charge is balanced by the
negative charge on the electrons. Therefore the atom becomes electrically neutral.
Rutherford’s nuclear model of the atom (1911):-
Rutherford studied the inside of an atom by his celebrated scattering experiment and put forth the nuclear model of the atom in the year 1911. Rutherford took a very thin gold foil (thickness: 10-4mm) and bombarded it with positively charged alpha – particles emitted by a radioactive element. He observed the path of alpha – particles by means of a fluorescent screen around the gold foil. It was expected that the a- particles would get reflected from the gold foil if the positively charged mass were evenly distributed inside the atoms. Unexpectedly, most of the alpha – particles went straight through the foil, then the small number of alpha – particles get deflected from the original path through a small angle, a still smaller number of a- particles get deflected through a larger angle, and surprisingly one alpha – particle out of 20000 bounced back in the direction opposite to the original path.
A large number of the alpha – particles that went straight through the foil indicates that there was no obstacle in their path. It meant that there must be mainly an empty space inside the atoms in the solid gold foil. The small number of alpha- particles that get deflected through a small or a big angle must have faced an obstacle in their path. It meant that the positively charged and heavy part causing obstruction would be in the centre of the atom.
Niel’s Bohr’s stable orbit atomic model (1913):-
In the year 1913 Danish scientist Niels Bohr explained the stability of atoms by putting forth a stable orbit atomic model. The important postulates of Bohr’s atomic model are as follows.
(i) The electrons revolving around the atomic nucleus lie in concentric circular orbits at a certain distance from the nucleus.
(ii) Energy of an electron is constant while it is in a particular orbit.
(iii) When an electron jumps from an inner orbit to an outer orbit it absorbs energy equal to the difference of its energy level and when it jumps from an outer orbit to an inner orbit it emits energy equal to the difference of its energy level.
Here I sum up the topic atomic structure model based on their progress in the theory & concept with a better version to explain atomic structure fundamental principles.
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