Depending on what the original charge of the atom is, when an e- is added, that charge will drop by one. If an atom loses an e- the charge will be one higher.
Atoms do not always contain the same number of electrons and protons, although this state is common. When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges (the electrons) and positive electric charges (the protons). The total electric charge of the atom is therefore zero and the atom is said to be neutral. In contrast, when an atom loses or gains an electron (or the rarer case of losing or gaining a proton, which requires a nuclear reaction), the total charges add up to something other than zero. The atom is then said to be electrically charged, or "ionized". There is a major difference between the neutral state and the ionized state. In the neutral state, an atom has little electromagnetic attraction to other atoms. Note that the electric field of a neutral atom is weak, but is not exactly zero because the atom is not a point particle. If another atom gets close enough to the atom, they may begin to share electrons. Chemically, we say that the atoms have formed bonds.
In multicellular organisms, the body is a system of multiple interacting subsystems. These subsystems are groups of cells that work together to form tissues and organs that are specialized for particular body functions.
Well, not always. It depends on where you're doing the boiling. In fact, water will boil at about 202 degrees in Denver, due to the lower air pressure at such high elevations
