In their standard form, atoms are not positive or negative; they are electrically neutral. An atom is the basic building block of all matter, composed of even smaller particles that carry distinct electrical charges. Understanding the fundamental nature of the atom begins with recognizing this initial state of balance.
The Standard Atom: A State of Neutrality
The electrical charge of an atom in its most stable state is zero. This neutrality is not a lack of charge, but a perfect cancellation of opposing charges within the structure. Every atom contains an equal amount of positive charge and negative charge.
This precise balance ensures that the net electrical force exerted by the atom is zero. This inherent electrical balance defines the atom as a stable, uncharged entity.
The Role of Subatomic Particles
The electrical properties of an atom are determined by its three main subatomic particles: protons, neutrons, and electrons. These particles differ in location, mass, and electrical charge. The central core of the atom, called the nucleus, contains the protons and neutrons.
Protons are the source of positive charge, each carrying a charge of positive one (+1). The number of protons is unique to each element and is known as the atomic number, which determines the element’s identity. Neutrons reside in the nucleus but are electrically neutral, carrying no charge.
Electrons orbit the nucleus in an electron cloud, each carrying a negative one (-1) charge. This charge is equal in magnitude but opposite to the proton’s charge. In a neutral atom, the number of electrons is exactly the same as the number of protons, achieving the net zero charge.
The Exception: When Atoms Gain or Lose Charge
Atoms become electrically charged, either positive or negative, when they are no longer in their standard, neutral state. This change occurs through ionization, which involves the atom gaining or losing electrons. The number of protons in the nucleus never changes during this process, as that would transform the atom into a different element.
Cations (Positive Charge)
When an atom loses one or more electrons, it loses negative charge but retains the same number of positive protons. This imbalance results in a net positive charge, and the resulting charged particle is called a cation.
Anions (Negative Charge)
Conversely, an atom can gain one or more electrons. By adding negatively charged particles, the atom acquires an overall net negative charge. This negatively charged particle is known as an anion.