Question

A metal ion with a \(2+\) charge has 23 electrons and forms a compound with a halogen ion that contains 17 protons. a. What is the identity of the metal ion? b. What is the identity of the halogen ion and how many electrons does it contain? c. Determine the compound that it forms and name it.

Short answer

The metal ion is manganese (Mn) with a 2+ charge. The halogen ion is the chloride ion (Cl-) with 17 protons and 18 electrons. The compound formed is manganese (II) chloride (MnCl2).

Step-by-step solution

Determine the protons in the metal ion

Since the metal ion has a 2+ charge, it means that it has lost 2 electrons. To find its number of protons, we need to add 2 to its electron count: Protons in the metal = 23 + 2

Identify the metal and its symbol

The metal ion has 25 protons, which corresponds to the element manganese (Mn) according to the periodic table.

Determine the electrons in the halogen ion

We know that the halogen ion has 17 protons. In a neutral state, the number of electrons is equal to the number of protons. However, halogens typically gain one electron to achieve a more stable electron configuration. So, the halogen ion would have 18 electrons due to the gained electron.

Determine the identity of the halogen ion

A halogen with 17 protons is chlorine (Cl). Since it has gained an electron, the halogen ion is the chloride ion (Cl-).

Write the chemical formula for the compound

Now, we need to determine the chemical formula for the compound formed between the metal and halogen ions. To create a neutral compound, the charges must cancel out. Since the manganese ion has a 2+ charge and the chloride ion has a 1- charge, two chloride ions are needed to balance the charge. The compound is: MnCl2

Name the compound

To name an ionic compound, we simply combine the name of the metal and halogen ions. In this case, the compound is manganese (II) chloride. The (II) is used to indicate the charge on the manganese ion since manganese can form ions with different charges.

Key concepts

Metal Ions

Metal ions are atoms that have lost one or more of their electrons, resulting in a positive charge. This occurs because the number of protons, which are positively charged, exceeds the number of electrons. The charge on a metal ion is often denoted as a superscript after the element symbol, indicating how many electrons have been lost.

Consider the exercise where a metal ion has a \(2+\) charge and 23 electrons. This means the ion originally had 25 electrons, matching the number of protons for it to be neutral. With 25 protons, this element is manganese, as found in the periodic table. Manganese can often display different charges, but in this instance, it bears a \(2+\) charge as it forms compounds with halogens.

Common characteristics of metal ions include:

• High melting and boiling points
• Good electrical conductivity in their solid and liquid states
• The capacity to form metallic bonds and ionic bonds with non-metals

These properties are vital for understanding how metal ions interact to form compounds.

Halogen Ions

Halogens are a group of elements found in Group 17 of the periodic table. They are known for being highly reactive, especially with metals. This high reactivity is due to their tendency to gain one electron, filling their outer electron shell and achieving a stable electron configuration. When halogens gain this electron, they form negatively charged ions known as halide ions.

In the given exercise, the halogen ion contains 17 protons, identifying it as chlorine. Chlorine, when it gains an electron, becomes the chloride ion ( Cl^- ), which has 18 electrons. Halide ions, such as the chloride ion, are frequently found in various compounds due to their ability to readily bond with metal ions.

Key points about halogen ions include:

• They are highly electronegative, meaning they have a strong tendency to attract electrons.
• Halogen ions like fluoride, chloride, bromide, and iodide play essential roles in both biological and industrial applications.
• They often form ionic bonds with metals, resulting in compounds like sodium chloride (table salt) and manganese (II) chloride.

Understanding these properties is important for recognizing how halogens function in compound formation.

Chemical Formula

A chemical formula represents the proportions of atoms in a compound. It gives insight into the elemental composition and the ratios in which these atoms combine. In ionic compounds, positively charged metal ions balance the charges of negatively charged non-metal ions to create a neutral structure.

For the exercise, we explore the combination of manganese (Mn^{2+}) and chloride (Cl^-) ions. Manganese has a \(2+\) charge, and each chloride ion has a \(1-\) charge. To balance the charges, two chloride ions are needed for every manganese ion, resulting in the chemical formula MnCl_2.

When writing chemical formulas for ionic compounds:

• Identify the charges of the involved ions.
• Combine ions in ratios that neutralize the overall charge.
• Provide the simplest whole number ratio of ions, as in MnCl_2.

Writing accurate chemical formulas is fundamental for naming compounds and understanding their properties, as in manganese (II) chloride, where the (II) indicates the manganese ion's charge.