The charge on an electron is:
positive
negative
neutral
unknown

negative

Firstly it is best to describe the shape and structure of an atom, an atom's system and structure is like of the solar planet, the heliocentric view where the sun is the neutrons and protons and the planets are the electrons. Moreover, the electrons are outside these neutrons and protons surrounding the entire system of its atomic structure. Its movement is like of a planet. 

An energy level also known as electron shell, or just shell is a location around an atom where electrons with a specific  energy value,  or quantum number may be found.

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.