The atomic model that describes an atom as a spherical object containing a certain number of electrons trapped in a mass of positive charge is often called model.

This atomic model was developed in 1904 by the British scientist J.J. Thomson, from his discovery of the existence of the electron in 1897.

Taking into consideration that at that time there was still no evidence of the atom nucleus, Thomson thought the electrons (with negative charge) were immersed in a substance (the atom) of positive charge that counteracted the negative charge of the electrons. Just like the raisins embedded in a pudding or bread.

That is why this model was called the raisin pudding atomic model

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.