Problem 34 - Chemistry The Molecular Nature of Matter

Question

How many electrons has a titanium atom lost if it has formed the ion \(\mathrm{Ti}^{4+}\) ? What are the total numbers of protons and electrons in a \(\mathrm{Ti}^{4+}\) ion?

Step-by-Step Solution

Answer

A \(\mathrm{Ti}^{4+}\) ion has lost 4 electrons. It has a total of 22 protons and 18 electrons.

Step 1: Identifying the Charge

First, we must identify the charge of the titanium ion, which is indicated by the superscript. A \(\mathrm{Ti}^{4+}\) ion has a 4+ charge, meaning it has lost 4 electrons compared to a neutral titanium atom.

Step 2: Determining Number of Electrons Lost

Since the charge is 4+, this means the titanium ion has lost 4 electrons. A neutral titanium atom would have the same number of protons and electrons, which is equal to its atomic number.

Step 3: Calculating Total Number of Protons

The atomic number of titanium (Ti) is 22, which means a neutral titanium atom has 22 protons. The number of protons does not change when an atom forms an ion. Therefore, the \(\mathrm{Ti}^{4+}\) ion also has 22 protons.

Step 4: Calculating Total Number of Electrons in the Ion

To find the total number of electrons in the \(\mathrm{Ti}^{4+}\) ion, subtract the number of electrons lost (4) from the atomic number of titanium. This gives you \(22 - 4 = 18\) electrons in the \(\mathrm{Ti}^{4+}\) ion.

Key Concepts

Ionic Charge

When we talk about ionic charge, we are referring to the electrical charge of an ion. An ion is an atom or molecule that has lost or gained one or more electrons, giving it a net positive or negative charge. This happens because electrons, which have a negative charge, are either removed from or added to an atom.

In the case of a titanium ion with a 4+ charge, denoted as \(\mathrm{Ti}^{4+}\), this means that the ion has lost four electrons. If an atom loses electrons, it becomes positively charged since it now has more protons, which are positively charged, than electrons. The number after the plus sign indicates exactly how many electrons have been lost.

Atomic Number

The atomic number of an element is incredibly important in chemistry. It is denoted by a whole number and represents the number of protons found in the nucleus of an atom of that element. Every element has a unique atomic number that defines its identity.

For example, titanium has an atomic number of 22, which means that every neutral atom of titanium will have 22 protons in its nucleus. It is this number of protons that determines the element's position in the Periodic Table of Elements. The atomic number is also equal to the number of electrons in a neutral atom, which is critical when discussing ions and their charges.

Protons in Ions

Protons are the positively charged particles within the nucleus of an atom, and their number is sacrosanct when it comes to the identity of an element. When an atom becomes an ion, the number of protons does not change. Instead, what changes is the number of electrons.

For instance, the \(\mathrm{Ti}^{4+}\) ion still has the 22 protons that a neutral titanium atom would have because the atomic number of titanium is 22. Hence, the number of protons in ions remains unchanged, regardless of the ion's charge. This constancy provides a solid foundation in understanding the properties and behavior of ions.

Electrons in Ions

An ion's charge largely depends on the number of electrons surrounding an atom's nucleus. In a neutral atom, the number of electrons equals the number of protons; however, ions are formed when an atom loses or gains electrons, resulting in an imbalance.

In the case of the \(\mathrm{Ti}^{4+}\) ion, we know from its charge that it has lost four electrons. If we start with the atomic number of titanium (22), representing the number of electrons in a neutral titanium atom, and we subtract four—the number of electrons lost—we find that the \(\mathrm{Ti}^{4+}\) ion has 18 electrons. So, while the number of protons stays the same, the number of electrons in an ion directly correlates with its ionic charge.