The number of protons is equal to the number of electrons.
Explanation
An atom is the fundamental unit of matter, consisting of subatomic particles: protons, neutrons, and electrons. The overall electrical state of an atom is determined by the arithmetic sum of the charges of its constituent particles.- Neutrons balance the charge of protons. is incorrect: Neutrons are located in the nucleus but are electrically neutral (charge = 0). Therefore, they play no role in balancing the positive charge of the protons.
- The number of protons is equal to the number of electrons. is correct: Protons, located in the nucleus, carry a positive charge (+1). Electrons, located in orbitals surrounding the nucleus, carry an equal magnitude of negative charge (-1). For an atom to be electrically neutral, the total number of protons must exactly equal the total number of electrons, resulting in a net charge of zero.
- The nucleus shields the positive charge from the electrons. is incorrect: The nucleus does not shield positive charge from electrons; rather, it exerts an electrostatic force of attraction on them. Shielding refers to the repulsion inner electrons exert on outer electrons, which is a different concept unrelated to the definition of neutrality.
- Electrons are embedded in the nucleus to neutralize it. is incorrect: Electrons are not embedded in the nucleus. According to the nuclear model of the atom, protons and neutrons reside in the nucleus, while electrons revolve around the nucleus in specific energy levels.
Key Takeaway: An atom is electrically neutral solely because the number of positively charged protons is equal to the number of negatively charged electrons.