Question

Determine the charge of each of the following: a. a rubidium atom that has lost one electron b. an iodine atom that has gained one electron c. an iron atom that has lost two electrons

Short answer

a. Rubidium after losing one electron has a charge of +1. b. Iodine after gaining one electron has a charge of -1. c. Iron after losing two electrons has a charge of +2.

Step-by-step solution

- Determine the Charge of Rubidium after Losing an Electron

Rubidium (Rb) has an atomic number of 37, meaning it has 37 protons and, when neutral, 37 electrons. If a rubidium atom loses one electron, it will have one more proton than electrons. The charge of an ion is determined by the difference between the number of protons and electrons. Therefore, a rubidium ion after losing one electron will have a charge of +1.

- Determine the Charge of Iodine after Gaining an Electron

Iodine (I) has an atomic number of 53, meaning it has 53 protons and, when neutral, 53 electrons. If an iodine atom gains one electron, it will have one more electron than protons. As a result, an iodine ion after gaining one electron will have a charge of -1.

- Determine the Charge of Iron after Losing Two Electrons

Iron (Fe) can have multiple oxidation states, but if it loses two electrons, which is common for iron, it will typically be in the +2 oxidation state. This is because the neutral iron atom with an atomic number of 26 has 26 protons. After losing two electrons, the iron ion will have 26 protons and 24 electrons, resulting in a charge of +2.

Key concepts

Oxidation States

Understanding oxidation states is vital when determining the charge of ions. In chemistry, the oxidation state, often referred to as oxidation number, is a value that indicates the degree of oxidation of an atom in a chemical compound. The oxidation state of an atom is the charge that atom would have if all bonds to atoms of different elements were completely ionic.

Oxidation states are assigned based on a set of rules. For example, the oxidation state of an atom in its elemental form is zero, while for a monoatomic ion, the oxidation state is equal to the charge of the ion. In compounds, the usually more electronegative element is assigned a negative oxidation state. In the case of iron losing two electrons, as mentioned in the original exercise, its common oxidation state is +2, indicating that the iron ion has lost two electrons and thus has a positive charge. Correctly identifying oxidation states can help predict how atoms will interact during chemical reactions.

Atomic Number

The atomic number is a fundamental concept in understanding the charge of ions. It is defined as the number of protons present in the nucleus of an atom. Since protons are positively charged, the atomic number also reflects the positive charge of the nucleus. A neutral atom has the same number of electrons as protons, balancing the overall charge.

However, when atoms gain or lose electrons, they become ions and their charge changes. For instance, rubidium (Rb) with an atomic number of 37 usually has an equal number of 37 electrons to maintain neutrality. But when a rubidium atom loses an electron, as described in our exercise, the number of protons remains unchanged while the number of electrons decreases, creating a positively charged ion with a charge of +1.

Charge of Ions

The charge of ions is determined by the difference in the number of protons and electrons in an atom. When an atom gains or loses electrons, it becomes an ion—a charged particle. If the number of electrons exceeds the number of protons, the ion is negatively charged; conversely, if the number of protons exceeds the number of electrons, the ion is positively charged.

The concept of such ionic charge is illustrated by the iodine atom in our exercise solution. Iodine normally has 53 protons and 53 electrons, but upon gaining an electron, the negative charge increases, leading to a net charge of -1 for the iodine ion. Understanding the creation of these charges is crucial for many areas of chemistry, including electrochemistry and the study of electrolytes.

Electron Gain and Loss

Electron gain and loss are processes that transform neutral atoms into charged ions. Electrons have a negative charge, and when an atom gains an electron, it becomes negatively charged, known as an anion. Conversely, when an atom loses an electron, it becomes positively charged, and is referred to as a cation.

The concept of electron gain and loss is demonstrated in the case of the iron atom from the exercise, which becomes a cation with a +2 charge after losing two electrons. These processes are fundamental in chemical reactions and play a significant role in the formation of compounds. For example, when sodium (Na) loses an electron and chlorine (Cl) gains an electron, they form the ionic compound sodium chloride (NaCl), also known as table salt.