Question

[02.01]In the 1800s, John Dalton's atomic theory proposed that atoms are indivisible. Later, subatomic particles such as neutrons, electrons and protons were discovered. What happened to the indivisible part of Dalton's atomic theory and why?

Answer 1

After the discovery of subatomic particles, the indivisible part of the theory was discarded as the accord of data must prevail for the theories to be valid.

John Dalton is famous for his atomic theory that illustrates that matter is formed of indivisible atoms. The discovery of the sub-atomic particles was first done by JJ Thomson in 1897 when he found electrons. In 1920 discovery of protons was done by Rutherford, and in 1932 discovery of neutrons was done by James Chadwick.

This resulted in the shifting of the pattern that atom is imperishable as novel discoveries led to modifications in the accord data that opposed the atomic theory. This disapproved the indivisible atomic theory.

Answer 2

There came other atom models: Thompson’s model, Rutherford’s model, Bohr’s model… and finally, Schrödinger’s theory.

Besides, keep in mind that:
-When an atom loses an electron, that electron has to end up in another atom, and then you have cations and anions… and a cation always has to be near an anion… so they are sort of keeping an eye on their missing electrons.
-The only situation where we find isolated neutrons is during nuclear reactions… and remember those are dangerous chain reactions! The atomic bomb is an example of that.
-We can have isolated protons and we call them H+ - so it works as any other cation. You can find H+ in water, where we also have OH-.

Let’s talk about Thompson’s model: They call it the “plum pudding”. It consisted on a large positive charge (the pudding) filled with little negative charges (the plums).

And this is Rutherford’s model: He found out negative charges (electrons) were actually spinning around the positive nucleus. But he didn’t say anything about the shapes or sizes of their orbits.

Then you have the Bohr’s model, also known as the planetary model. Bohr said that there are smaller orbits, closer to the nucleus, and larger orbits, in the outer part of the atom, and did propose a lot of detail about the orbits. But it still wasn’t enough accurate.

Schrödinger’s focused on finding more details about where in the atom you can find each electron, its velocity, its momentum, etc.