In basic atomic structure, atoms have no net electric charge because they contain which balanced combination of subatomic particles?

Introduction / Context:
This question tests your understanding of why ordinary atoms are electrically neutral. In atomic physics and chemistry, neutrality means that the total positive charge and the total negative charge in an atom cancel each other. The positive charge comes from protons in the nucleus, while the negative charge comes from electrons in the surrounding electron cloud. Neutrons are electrically neutral particles and do not contribute to the net charge. Recognising that neutrality arises because the number of electrons equals the number of protons is fundamental for understanding ions, isotopes, and periodic trends.

Given Data / Assumptions:
- Atoms are said to have no net electric charge under normal, neutral conditions.
- Three types of subatomic particles are involved: protons, electrons, and neutrons.
- Proton charge is positive, electron charge is negative, neutron charge is zero.
- The question asks which equality between particle counts explains atomic neutrality.

Concept / Approach:
The atomic number of an element equals the number of protons in its nucleus. In a neutral atom, the number of electrons equals the number of protons. Because each proton has a single positive charge and each electron has a single negative charge of the same magnitude, equal numbers of these particles result in zero net charge. Neutrons do not affect charge because they are electrically neutral and only contribute to the mass number. The correct conceptual approach is therefore to link neutrality to the equality between the number of electrons and the number of protons, not to any relationship involving neutrons.

Step-by-Step Solution:
Step 1: Recall that each proton carries a positive charge of +1 (in elementary charge units) and each electron carries a negative charge of -1. Step 2: Understand that neutrons have no electric charge and therefore do not change the total charge of the atom. Step 3: For an atom to have no net charge, the sum of positive and negative charges must be zero. Step 4: This happens only when the number of electrons equals the number of protons, so that total positive charge equals total negative charge in magnitude. Step 5: Therefore, the condition that explains why atoms are electrically neutral is that they have the same number of electrons and protons.

Verification / Alternative check:
Consider a simple example such as a neutral hydrogen atom. It has one proton and one electron. The charges are +1 and -1, which add up to zero, confirming neutrality. If the hydrogen atom loses its electron, it becomes an H+ ion with a net positive charge because the number of protons exceeds the number of electrons. Similarly, for a neutral oxygen atom with 8 protons and 8 electrons, the charges again cancel. Changes in neutron number create isotopes but do not affect the total charge. These examples confirm that equality between protons and electrons, not any involvement of neutrons, is what ensures zero net charge in a neutral atom.

Why Other Options Are Wrong:
Having the same number of electrons and neutrons does not guarantee neutrality, because neutrons are uncharged and do not balance positive charge. Having the same number of protons and neutrons only affects the mass number and isotopic form, not the net electric charge. Having the same number of protons, electrons, and neutrons is an unnecessary and often incorrect condition; many elements do not have equal numbers of all three. Only the equality between protons and electrons is required for neutrality, so the other options are misleading and incorrect.

Common Pitfalls:
Students often confuse mass number (protons plus neutrons) with atomic number (protons only) and may think that neutrons play a role in balancing charge. Another common mistake is to assume that a stable atom must have equal numbers of all three particles, which is false for most elements. Remember that charge neutrality is purely about balancing positive and negative charges, so neutrons do not enter into that calculation. Once you internalise that protons give positive charge and electrons give negative charge of equal magnitude, it becomes easy to see why their counts must be equal in neutral atoms.

Final Answer:
Atoms have no net electric charge because they have the same number of electrons and protons.