Question

How many of each type of subatomic particle (protons and electrons) is in (a) an atom of tin? (b) a Sn \({ }^{2+}\) ion? (c) a Sn \({ }^{4+}\) ion?

Short answer

A neutral atom of tin has 50 protons and 50 electrons. A Sn \( {}^{2+} \) ion has 50 protons and 48 electrons, while a Sn \( {}^{4+} \) ion has 50 protons and 46 electrons.

Step-by-step solution

Determine the Atomic Number of Tin

Find the atomic number of tin (Sn) in the periodic table. The atomic number is the number of protons in an atom of the element and it's equal to the number of electrons in a neutral atom.

Determine the Number of Protons and Electrons in a Neutral Atom of Tin

Since the atomic number of tin is 50, a neutral atom of tin contains 50 protons and 50 electrons.

Analyze the Sn \( {}^{2+} \) Ion

A Sn \( {}^{2+} \) ion has lost 2 electrons. Therefore, it contains 50 protons, as the number of protons does not change, and 48 electrons.

Analyze the Sn \( {}^{4+} \) Ion

A Sn \( {}^{4+} \) ion has lost 4 electrons. Therefore, it contains 50 protons and 46 electrons.

Key concepts

Atomic Number

Understanding the atomic number is fundamental in chemistry, as it signifies the number of protons found in the nucleus of an atom. For any element on the periodic table, the atomic number defines the element's identity. For instance, tin (Sn) has an atomic number of 50, which means every atom of tin has 50 protons in its nucleus.
This number is crucial because it not only identifies the element, but also tells us about the number of electrons in a neutral atom. Electrons are negatively charged subatomic particles that orbit the nucleus. In a neutral atom, the number of electrons is equal to the number of protons to balance the charge. So, a neutral tin atom contains 50 electrons. When considering the atomic number, remember that it remains constant across all atoms of the same element, whether they are part of a molecule, a solid, a liquid, or a gas.

Protons and Electrons

The interplay between protons and electrons dictates an atom's charge and chemistry. Protons are positively charged particles in the nucleus, while electrons are negatively charged and are located in orbital shells around the nucleus. The number of protons is pivotal as it defines the atomic number and thus the element itself, as seen with tin's 50 protons.
Electrons are equally interesting because they can be gained or lost, leading to the formation of ions, which carry a charge. In a neutral atom, such as a neutral tin atom, the electrons mirror the number of protons resulting in a net zero charge. Exploring their behavior under various conditions helps us understand chemical reactivity and bonding. For example, chemical bonding typically involves the interactions between electrons of different atoms.

Ions

An ion is an atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons. When an atom like tin loses electrons, it becomes a positively charged ion, referred to as a cation. The tin ion with a charge of +2, denoted as Sn\( {}^{2+} \), means that tin has lost 2 electrons, having 48 electrons remaining but still maintaining 50 protons. Similarly, Sn\( {}^{4+} \) has 46 electrons due to the loss of 4 electrons.
The phenomenon of ion formation is crucial for understanding chemical reactions, electrical conductivity in materials, and the function of electrolytes in biological systems. A positively charged ion is attracted to negatively charged ions and repelled by other positive ions. This interplay of charges is the basis of the intricate dance that drives chemical interactions and the formation of new substances.