Structure of atoms

Rutherfords model?

an atom is like a solar system with electrons orbiting around the nucleus.

Bohrs Postulate 1?

Electrons can be found on certain orbits and only radiate there.

Bohrs Postulate 2?

Electrons can jump between shells to emit radiation.

JJ Thomson’s experiment?

performed experiments with cathode ray tubes and concluded that it consisted of identical particles independent of the element used for the cathode or filling gas, so the particles must be present in atoms of every element.

Thomson’s model?

said an atom is a homogeneous, positively charged liquid- like substance completely filled with tiny, negatively charged electrons in it (Plum- pudding model)

Franck Hertz experiment?

Electron collision with Hg atoms, electrons are accelerated by the electric field between the cathode (C) and the grid (G) in a tube filled with Hg vapour. When they pass through a field of opposite voltage they slow down and are not able to reach the anode is they don’t have enough K.E .

Frequency of light emitted in changing energy levels?

hf = E2 - E1 E1 = -13.6ev

Rutherfords experiment deduced that?

Some particles pass straight through, some scattered at low angles and some scattered back

Balmer formula?

hv = hc/wavelength

Bohrs model?

Atoms radiate only when electrons jump from one level to another.

Line spectra of atoms?

Excitation of atoms to emit light at different wavelengths corresponding to different colours.

Line spectra for hydrogen?

Emission spectrum

Rydberg formula?

1/wavelength = R(1/n2 -1/k2)

What is h in Balmer formula?

Planck constant

What is the formula for v?

v= c/wavelength

Angular momentum formula?

L = mvr

Problems of Rutherfords model?

An atom with constantly accelerating electrons will not be stable cause they will radiate and lose energy.

What did Franck Hertz experiment prove?

Evidence of energy quanta

What happens to the electrons that reach the anode?

Form a measurable current (I)

Energy is quantized means?

Energy can only change by certain values

What was the plum pudding model?

Thomson’s model of atom