Question

Which of the following particles always are present in equal number in a neutral atom? A. protons, neutrons B. electrons, neutrons c. protons, electrons D. electrons, ions

Short answer

Protons and electrons (option C) are always equal in number in a neutral atom.

Step-by-step solution

Understanding Neutral Atoms

A neutral atom has no overall electrical charge, which means that the total number of positive charges (protons) must be equal to the total number of negative charges (electrons). Neutrons, however, are neutral and do not affect the electrical charge.

Explanation of Particles

- *Protons* are positively charged particles found in the nucleus. - *Electrons* are negatively charged particles orbiting the nucleus. - *Neutrons* are neutral particles found in the nucleus. - *Ions* are atoms that have lost or gained electrons, thus carrying a charge, which doesn't relate to a neutral state.

Analyzing the Answer Choices

A. Protons (positive) and neutrons (neutral) do not always equal each other in number. B. Electrons (negative) and neutrons (neutral) also do not always have equal numbers. C. Protons (positive) and electrons (negative) must always be equal in number for the atom to be neutral. D. Electrons and ions are not directly comparable, as ions result from an imbalance in electrons.

Solution Verification

Based on the requirements for a neutral atom, the only pair that is always equal is that of protons and electrons. This is necessary to ensure that the total positive charge is balanced by an equal total negative charge, leading to no overall charge.

Key concepts

Protons

Protons are fundamental particles that reside in the nucleus at the core of an atom. They have a positive electrical charge, represented by the symbol $+1$. This charge is crucial because it determines the identity of the element. Each element has a unique number of protons, known as its atomic number. For instance, carbon always has six protons. This is what makes it carbon.

Not only do protons define an element, but they also combine with neutrons to contribute to the atom's mass. Although they exist in the dense nucleus, the forces binding them together are strong enough to overcome their mutual repulsion due to similar charges. In a neutral atom, the number of protons is always balanced by an equal number of electrons, ensuring the atom's neutrality.

• Protons define the element's identity.
• Each element's atomic number is determined by its protons.
• Protons carry a +1 charge and reside in the nucleus.

Electrons

Electrons are negatively charged particles that orbit the nucleus of an atom. The charge of each electron is $-1$. Their movement around the nucleus is not random but instead constrained to certain energy levels, often referred to as electron shells.

Electrons are key players in chemical bonding and reactions. In a neutral atom, the number of electrons equals the number of protons. This equality ensures that the atom has no overall charge. When atoms gain or lose electrons, they become ions, carrying either a positive or negative charge and ceasing to be neutral.

• Electrons are responsible for the negative charge in atoms.
• They orbit the nucleus in specific energy levels.
• Equal number of electrons and protons make an atom neutral.

Neutrons

Neutrons are fascinating particles that, as their name suggests, carry no charge, making them electrically neutral. They reside alongside protons in the atomic nucleus. While they don't influence the atom's charge, they play a critical role in its stability.

The number of neutrons in an atom can vary, which leads to different isotopes of an element. Isotopes have the same number of protons but different numbers of neutrons, resulting in varying atomic masses. Despite their lack of charge, neutrons' presence is crucial in keeping the protons bound within the nucleus, counteracting the repulsive forces between the positively charged protons.

• Neutrons are neutral particles in the nucleus.
• They influence atomic stability rather than charge.
• Isotopes vary in the number of neutrons.