Planetarni model atoma (pasivni)

Tomsonov model atoma (model pudinga sa šljivama)
Džon Džozef Tomson, radeći na katodnim cevima, otkriva elektrone i njihovu subatomsku prirodu, pa dolazi do rušenja koncepta atoma kao realno fizički nedeljive čestice. Tomson je dao svoj model atoma, po kome su negativni elektroni ravnomerno raspoređeni po atomu, a njihovo naelektrisanje je uravnoteženo uniformnom pozitivno naelektrisanom masom. On je zapravo smatrao da je atomsko jezgro homogeno naelektrisana masa koncipirana u sferu u koju su zabodeni elektroni kao šljive u puding i da je „drhtanje“ šljiva analogno oscilacijama elektrona oko svojih položaja. Tomsonov model pudinga sa šljivama, dugo je bio u opticaju, sve dok se nije pojavio Raderford i njegov planetaran model.

Raderfordov model
Kada se metalna folija bombarduje α česticama, jedan deo pozitivno naelektrisanih čestica u sudaru sa pozitivnim naelektisanjem atoma skreće sa prvobitne putanje, dakle, rasejava se, dok drugi, veći deo, ipak prolazi kroz foliju. Međutim, poneka čestica skrene za neočekivano veliki ugao (kao da se odbije od folije). Analizirajući ovaj problem, Raderford je zaključio da su celokupna masa i pozitivno naelektrisanje atoma skoncentrisani u vrlo malom prostoru, dakle, da postoji jezgro atoma. Tako je nastao planetaran model atoma. Ulogu planeta preuzeli su elektroni, a atomsko jezgro je dobilo funkciju Sunca. Raderfordov model jhe bio revolucionaran i eksperimentalno dokaziv, ali ga je u narednim decenijama popravljala grupa naučnika, kao što su Bor, Hajzenberg, Pauli…



Planetary model of the atom (passive)

 

Thomson’s model of the atom (plum pudding model)
Sir Joseph John Thomson, working on the cathode ray tubes, discovered electrons and their subatomic nature, which led to breaking the concept of the atom as a physically indivisible particle. Thomson presented his own model of the atom, in which negative electrons were uniformly distributed in the atom, and their charge was equalled with the uniform positively charged mass. Actually, he thought that the atomic nucleus were homogeneously charged mass in the shape of a sphere in which electrons were distributed like plums in plum pudding and that “shivering” of plums is analogous to oscillations of electrons in their positions. Thomson’s plum pudding model was valid for a long time, until Rutherford appeared with his planetary model.
Rutherford’s model

When the metal foil was bombed with α particles, one part of positively charged particles in collision with the positive charge of the atom changed its original path, and thus were scattered, while the other, larger part penetrated the foil. However, some particles made unexpectedly sharp turn (as if being deflected from the foil). Analyzing this problem, Rutherford concluded that the whole mass and the positive charge of the atom were concentrated in a very small space ant that there was the nucleus of the atom. This is how the planetary model was made. Electrons took the role of planets, while the Sun was represented by the nucleus. Rutherford’s model was revolutionary and it could be proved by experiments, but it was further developed by a group of scientists such as Bohr, Heisenberg, Pauli…