Final answer:
An atom is electrically neutral because it has equal numbers of positively charged protons and negatively charged electrons, which cancel each other out. The atomic number determines the number of electrons, which defines many of the atom's properties. Ions occur when this balance is disrupted with an unequal number of protons and electrons. Correct option is A.
Step-by-step explanation:
An atom is electrically neutral because it contains the same number of positively charged protons and negatively charged electrons. These charges cancel each other out, resulting in no net charge. Electrons, designated as e, have a negative charge, while protons, designated as p+, have a positive charge. Neutrons have no charge and are electrically neutral. The number of protons and electrons within a neutral atom are equal, keeping the atom's overall charge balanced. The atomic number of an atom tells you how many electrons the atom has, which also determines many of the atom's chemical properties.
Atoms become ions when they have a disparity in the number of protons and electrons. An atom with more electrons than protons has a negative charge, and an atom with fewer electrons than protons has a positive charge. Protons and neutrons are bound in the nucleus due to the strong nuclear force, while electrons are attracted to the positively charged nucleus by the electromagnetic force.