collect information about periodical development of fundamental particles and structure of atom with different atomic models and display them in information chart
Answers
many scientists and philosophers did continuous research for understanding the concept of atom and its structure. we can't forget their hard work. but for brief explanation, we just take some very important theory and concepts which are fruitful to understand atomic model.
development of fundamental structure of atoms can be understood by five steps.
1. JJ Thomson modal of atom : JJ Thomson discovered the electron while experimenting with cathode rays. he said " the electrons
were like plums embedded in a positively charged “pudding,” thus it was called the “plum pudding” model.
2. Ernst Ratherford scattering experiment : Rutherford experiment is so famous and more precise. he discovered proton. he said " All of the positive charge, and most of the mass of an atom are concentrated in a small core, called the nucleus.
he gave the evidence from his awesome experiment : (a) The atom is mostly empty space.
(b). All the positive charge, and almost all the mass is concentrated in a small area in the center. He called this a “nucleus”.
(c). The nucleus is composed of protons and neutrons (they make the nucleus).
(d). The electrons distributed around the nucleus, and occupy most of the volume His model was called a “nuclear model.
3. Discovery of neutron :- James Chadwick was discovered neutron. Chadwick bombarded alpha particles (He nuclei) at Beryllium. Neutrons were emitted and in turn
hit parafin and ejected protons from the parafin.
4. Bohr's atomic model :- Bohr was the first scientist who set atomic model in mathematical operations. he define the shape and size by using mathematical terms. according to him, the electron moves in circular orbits around the proton under the influence of the attractive electric field.
5. Scrödinger's model of atom :- his model most precise and are used in the present days.
according to him,electron shells don’t have the same amounts of energy. Scrödinger called for sub-shells. Each shell is divided into subshells
(also called sub-energy levels) - regions within a shell that have a similar amount of energy
These have characteristic shapes and different amounts of energy.
s < p < d < f < g
Periodical development of fundamental particles :
- About 2600yrs ago, an Indian sage called Kanada actual called by name Kasyapa proposed that all forms of matter are composed of very small particles called as Anu and each anu may be made up of still smaller particle called Parmanu.
- Later Democritus called these atoms [ greek Word "Atomio " meaning indivisible "
- John Dalton atomic theory described elements in terms of atoms which he believed to be small , indivisible particles.
- Later John Dalton's Postulate Atom is indivisible is disproved because through various experiments conducted by scientist three fundamental particles were discovered
- Electron --- By J.J Thomson in 1897
- Proton --- By Gold Stein in 1920
- Neutron --- By James Chadwick in 1932
Structure of Atom:
Thomson Atomic model:
After the discovery of electrons J.J Thomson proposed his Plum Pudding model which shows electrons embedded through out the mass of positively charged material.
Rutherford alpha scattering experiment led to discovery of atomic nucleus.
Neil Bohr modified Rutherford Model of the atom by stating that electrons move in specific energy levels around Nucleus of atom.
Later Bohr Sommerfeld model though successful in accounting for the spectral line of H2 spectra but did not provide satisfactory picture of the structure of atom in general.
At last A quantum mechanical model of atom was developed by Erwin Schrodinger. According to this model, electrons are present in a particular region or space around the nucleus called as Orbital where probability of finding electrons are more.
