chair form

as the steric repulsions is minimum

electron domains in the valence shell of an atom will arrange themselves so as to minimize repulsions

When an electron is added to an atom, its size increases due to increase in repulsions between the electrons.

This is the maximum distance the atoms can be placed away from each other. If you change any of the angles, some of the atoms will be closer together and will experience steric repulsions. By placing the atoms 109.5 degrees apart, you minimize steric repulsions and free energy. ------------------------------------------------------ Edit (AY12345): You know the shape of the molecule. Draw it out. Use a little trigonometry, and the angles can be calculated mathematically.

Yes, a charge is the fundamental electric property to which the mutual attractions or repulsions between electrons or protons is attributed. Electric charges are constantly flowing.