For each of the following covalent bonds: (use the videos to help you with these steps)

Write the symbols for each element.

Draw a Lewis Dot and cross structure for the valence shell of each element.

Rearrange the electrons to pair up electrons from each atom.

Draw circles to show the sharing of electrons between each pair of atoms

Draw the bond structure using chemical symbols and lines. Use one line for each pair of electrons that is shared.

Write the chemical formula for each molecule.

Hydrogen + Hydrogen

Chlorine + Chlorine

Hydrogen + Chlorine

Hydrogen + Oxygen

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.