Problem 55 - Chemistry

Question

For each of the following ions, indicate the number of protons and electrons the ion contains. a. \(\mathrm{Ba}^{2+}\) e. \(\mathrm{Co}^{3}\) b. \(\mathrm{Zn}^{2+}\) f. \(\mathrm{Te}^{2}\) c. \(\mathrm{N}^{3-} \quad\) g. \(\mathrm{Br}^{-}\) d. \(\mathrm{Rb}^{+}\)

Step-by-Step Solution

Answer

The short answer based on the step-by-step solution is: a. Ba: 56 protons, 54 electrons b. Zn: 30 protons, 28 electrons c. N: 7 protons, 10 electrons d. Rb: 37 protons, 36 electrons e. Co: 27 protons, 24 electrons f. Te: 52 protons, 50 electrons g. Br: 35 protons, 36 electrons

Step 1: Determine the atomic number of the elements

To find the number of protons in each ion, we need to first determine the atomic number of the corresponding elements. The atomic numbers can be found in the periodic table. Here are the atomic numbers of each element: a. Ba (Barium) - 56 e. Co (Cobalt) - 27 b. Zn (Zinc) - 30 f. Te (Tellurium) - 52 c. N (Nitrogen) - 7 g. Br (Bromine) - 35 d. Rb (Rubidium) - 37

Step 2: Calculate the number of protons for each ion

Since the atomic number is equal to the number of protons, we can directly take the atomic numbers from Step 1 as the number of protons for each ion: a. Ba - 56 protons e. Co - 27 protons b. Zn - 30 protons f. Te - 52 protons c. N - 7 protons g. Br - 35 protons d. Rb - 37 protons

Step 3: Calculate the number of electrons for each ion

The charges of the ions indicate the difference between the number of protons and electrons. We can calculate the number of electrons for each ion by considering the charge on each ion: a. Ba - \(56 - 2 = 54\) electrons e. Co - \(27 - 3 = 24\) electrons b. Zn - \(30 - 2 = 28\) electrons f. Te - \(52 - 2 = 50\) electrons c. N - \(7 + 3 = 10\) electrons g. Br - \(35 + 1 = 36\) electrons d. Rb - \(37 -1 = 36\) electrons

Key Concepts

Protons and Electrons in Ions

Understanding how ions are formed and what they contain in terms of protons and electrons is a key aspect of mastering atomic structure. In essence, an ion is an atom that has gained or lost one or more electrons, causing it to be charged.

For example, when an atom loses an electron, it becomes positively charged and is known as a cation. Conversely, when an atom gains an electron, it becomes negatively charged, making it an anion. The number of protons in an ion remains unchanged and is determined by the element's atomic number.

Why is the Number of Protons Unchanged?

As the unique identifier of an element, the atomic number - the number of protons in the nucleus of an atom - stays constant, whether or not the atom is part of an ion. Changing the number of protons would transform the atom into a different element.

Calculating the Number of Electrons in Ions

To find out how many electrons an ion has, we consider the charge of the ion. If the ion is positively charged, we subtract the charge from the atomic number (protons) to get the number of electrons. If the ion's charge is negative, we add the charge to the atomic number to find the electron count.

Atomic Number

The atomic number is a fundamental concept in chemistry that defines an element's identity. It indicates the number of protons in the nucleus of an atom. Since each element has a unique number of protons, the atomic number effectively serves as its place holder within the periodic table.

Importance of the Atomic Number

The atomic number determines the chemical properties of the element and dictates its position on the periodic table. The elements are ordered in the periodic table by their atomic number, from the smallest to the largest. This organization helps categorize elements into groups with similar chemical behaviors.

When we encounter ions, the atomic number allows us to retain the identity of the ion's parent atom. Even though the number of electrons may change when an atom becomes an ion, the atomic number remains constant, ensuring we can always trace back to the original element.

Periodic Table

The periodic table is an organized display of chemical elements, arranged by increasing atomic number. Developed by Dmitri Mendeleev in the 19th century, it has become an invaluable tool for chemists and students alike, providing a framework for understanding the relationships between different elements.

Understanding the Layout

The table is structured into rows called periods and columns known as groups or families. Elements in the same group typically share similar properties and have the same number of valence electrons. The rows and groups help predict the behavior of elements during chemical reactions.

Navigating the Periodic Table

When solving exercises like identifying the number of protons and electrons in ions, the periodic table can be your best resource. The atomic number is usually located above the element symbol, allowing quick identification of how many protons and, consequently, electrons the neutral atom would have. With this information, adding or subtracting the ion's charge gives us the final electron count for the ion.