General Chemistry

Model of atoms/Historical development

The atomos concept

Proposed that matter cannot be devided infinitely.

The atomos Concept

Stated that metter is of tiny, had, indivisible aprticles called atomos.

Who proposed the “atomos concept”?

Democritus

When was the “atomos” concept proposed?

4000 BCE

What were the limitations of the Atomos Concept?

Entirely philosophical. There was no experimental evidence or testing to support his theories.

What is Dalton's atomcic theory?

Billiard ball Model (1803)

What formulated the very first conceptual framework of the atom?

The “atomos” concept

Stated that atoms are indivisible and atoms of a given elements are identical

John Dalton with his Billiard Ball Model

States that compoudns form in whole-numebr ratio

The Billiard Ball Model

Revived the atomic idea using quantitative measurements of the chemical reactions

John Dalton

Dalton claimed atoms are indivisible, what proved it wrong?

The discovery of subatomic particles: e-, p+, n

Dalton claimed that atoms for the same given element are identical, what proved it wrong?

The discovery of isotopes with different masses

What was J.J thomsons model?

The Plum pudding model (1897)

How did J.J thomson discovered electrons?

Using the cathode ray experiment

What did the cathode ray experiment proved?

That the atom has sub-particles

What is the plum pudding model?

Atom is a unifrom sphere of postive charge with negatively charged electrons embedded like raisins in pudding.

What was the limitations of J.J thomsons plum pudding model?

Lacked a nucleus, couldn't explain atomic stability and contradicted rutherfords gold foil experiment.

What was Ernest Rutherford's model?

The nuclear model

What was the Gold foil experiment?

Where Ernest Rutherford shot alpha aprticles at a thin gold foil, which majority passed through and a few deflected at extreme angles.

What did the Gold Foil experiment proved?

Most of the atom are empty spaces and That positive charge is in a dense, central nucleus.

What model is this and from who?

Plum Pudding Model from J.J thomson

What is this and from who?

Gold foil experiment from Ernest Rutherford's

What experiment or test that led Rutherford's to propose his nuclear model?

The Gold foil experiment

What was Rutherfords limitation?

He coudn't explain the atomic stability

What was the classical collapse praradox?

According to classical physics, moving charged particles must continously lose energy by emitting electromagnetic radiation.

What conclusion did John dalton come up with, with his billiard ball model?

1.) Matter consists of indivisible atoms

2.) Atoms of a given element are identical

3.) Compounds form in whole number ratio

What was the Bohr Model?

Planetary model (1913)

What was the planetary model?

That electrons traveled in a fix non radiating orbits called energy levels.

What did ernest rutherford nuclear model proved?

That a central nucleus exists

What was Niels Bohr model?

The Planetary Model

What did Niel bohr planetary model stated about electrons absorbing?

Electrons must absorb or emit the exact quanta of energy to jump between levels.

Why was his planetary model incomplete?

He assumed that electrons travelled in a strict, flat, preditable ciruclar path.

In planetary model of niel bohr, what do you call the Fixed ciruclar path that electrons traveled in?

Energy Level

Why did the planetary model failed?

Because it failed to accurately predict spectra for any multi-electron atom (anything heavier than hydrogen)

What principle did the Planetary model of Niel bohr contradicted?

The uncertainty Principle of Heisenberg

Who formulated a complex wave equation?

Erwin Schrodinger (1926)

What was the wave equation?

Described electrons behaving like standing waves rather than solid particles.

What was the heisenberg uncertainty principle (1927) ?

It impossible to know boht the exact postion and momentum of an electron at the exact same time.