History of Atomic Models: Democritus to Quantum Wave Functions

What did Democritus contribute to atomic theory?

He proposed the existence of atoms as indivisible particles, but his ideas were philosophical and lacked experimental evidence.

What are Dalton's four postulates regarding atoms?

1. Matter is made up of tiny, indivisible atoms (later proven partially incorrect). 2. All atoms of a given element are identical (proven incorrect). 3. Atoms are rearranged in chemical reactions but are never created or destroyed. 4. Atoms combine in whole number ratios to form compounds.

What model did J.J. Thomson propose and what did he discover?

He discovered electrons and proposed the 'plum pudding model', which suggested that atoms are composed of a positive 'goo' with electrons embedded in it.

What significant experiment did Ernest Rutherford conduct and what did he discover?

He performed the gold foil experiment, which led to the discovery of the nucleus of the atom, forcing a revision of atomic structure.

What did James Chadwick discover and how?

He discovered neutrons by bombarding beryllium with alpha particles and observing the resulting radiation.

What is the planetary model of the atom and who created it?

The planetary model, created by Niels Bohr, describes electrons traveling in well-defined orbits around the nucleus.

What concept did Erwin Schrödinger introduce regarding electrons?

He introduced the idea that we cannot know the exact position of an electron, leading to the concept of wave functions.

What was the main flaw in Dalton's postulate that all atoms of a given element are identical?

This was proven incorrect as isotopes of elements exist, which have different numbers of neutrons.

What is the significance of the gold foil experiment conducted by Rutherford?

It demonstrated that atoms have a small, dense nucleus at their center, leading to a new understanding of atomic structure.

What does the term 'plum pudding model' refer to?

It refers to J.J. Thomson's model of the atom, where electrons are embedded in a positively charged 'goo'.

What did Democritus believe about the divisibility of matter?

He believed matter was not infinitely divisible but made up of tiny, indivisible atoms.

What did Dalton's postulate about matter state?

Matter is made up of tiny atoms that are indivisible.

How did Rutherford's findings challenge previous atomic models?

Rutherford's findings challenged the plum pudding model by introducing the concept of a dense nucleus.

What is the importance of the concept of energy levels in atomic theory?

Energy levels describe the fixed orbits in which electrons can exist around the nucleus, as proposed by Niels Bohr.

What is the relationship between chemical reactions and atoms according to Dalton's postulates?

In a chemical reaction, atoms are rearranged but are never created or destroyed.

What did Schrödinger's wave function imply about electrons?

It implies that the exact position of an electron cannot be determined, only the probability of finding it in a certain area.

What was the primary limitation of Democritus's theory?

It lacked experimental evidence and was purely philosophical.