Question

Write the electron configuration for each of the following atoms and for the simple ion that the element most commonly forms. In each case, indicate which noble gas has the same electron configuration as the ion. a. aluminum, \(Z=13\) b. bromine, \(Z=35\) c. calcium, \(Z=20\) d. lithium, \(Z=3\) e. fluorine, \(Z=9\)

Short answer

a. Aluminum: Electron configuration: \[1s^2 2s^2 2p^6 3s^2 3p^1\]. Common ion: \[1s^2 2s^2 2p^6\] (Neon) b. Bromine: Electron configuration: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5\]. Common ion: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6\] (Krypton) c. Calcium: Electron configuration: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2\]. Common ion: \[1s^2 2s^2 2p^6 3s^2 3p^6\] (Argon) d. Lithium: Electron configuration: \[1s^2 2s^1\]. Common ion: \[1s^2\] (Helium) e. Fluorine: Electron configuration: \[1s^2 2s^2 2p^5\]. Common ion: \[1s^2 2s^2 2p^6\] (Neon)

Step-by-step solution

a. Aluminum, Z=13

1. Find the electron configuration for aluminum. Aluminum has 13 electrons, so its electron configuration will be: \[1s^2 2s^2 2p^6 3s^2 3p^1\] 2. Determine the electron configuration of the most common ion of aluminum. Aluminum most commonly forms a +3 ion by losing three electrons. The electron configuration of the ion is then: \[1s^2 2s^2 2p^6\] 3. Find the noble gas with the same electron configuration. Using the periodic table, we can determine that the noble gas with this electron configuration is Neon.

b. Bromine, Z=35

1. Find the electron configuration for bromine. Bromine has 35 electrons, so its electron configuration will be: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5\] 2. Determine the electron configuration of the most common ion of bromine. Bromine most commonly forms a -1 ion by gaining one electron. The electron configuration of the ion is then: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6\] 3. Find the noble gas with the same electron configuration. Using the periodic table, we can determine that the noble gas with this electron configuration is Krypton.

c. Calcium, Z=20

1. Find the electron configuration for calcium. Calcium has 20 electrons, so its electron configuration will be: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2\] 2. Determine the electron configuration of the most common ion of calcium. Calcium most commonly forms a +2 ion by losing two electrons. The electron configuration of the ion is then: \[1s^2 2s^2 2p^6 3s^2 3p^6\] 3. Find the noble gas with the same electron configuration. Using the periodic table, we can determine that the noble gas with this electron configuration is Argon.

d. Lithium, Z=3

1. Find the electron configuration for lithium. Lithium has 3 electrons, so its electron configuration will be: \[1s^2 2s^1\] 2. Determine the electron configuration of the most common ion of lithium. Lithium most commonly forms a +1 ion by losing one electron. The electron configuration of the ion is then: \[1s^2\] 3. Find the noble gas with the same electron configuration. Using the periodic table, we can determine that the noble gas with this electron configuration is Helium.

e. Fluorine, Z=9

1. Find the electron configuration for fluorine. Fluorine has 9 electrons, so its electron configuration will be: \[1s^2 2s^2 2p^5\] 2. Determine the electron configuration of the most common ion of fluorine. Fluorine most commonly forms a -1 ion by gaining one electron. The electron configuration of the ion is then: \[1s^2 2s^2 2p^6\] 3. Find the noble gas with the same electron configuration. Using the periodic table, we can determine that the noble gas with this electron configuration is Neon.

Key concepts

Ions

Atoms can gain or lose electrons to form ions, which are charged particles crucial in many chemical reactions. When an atom loses electrons, it forms a positively charged ion called a cation. For example, aluminum, with an atomic number of 13, loses three electrons to become an Al³⁺ ion. This involves shedding electrons from its outer shell, adjusting its electron configuration to resemble that of a noble gas, thus stabilizing it energetically.

Conversely, when an atom gains electrons, it forms a negatively charged ion known as an anion. Bromine, for instance, with its atomic number of 35, typically gains one electron to complete its outer shell and forms a Br^- ion. In doing so, its configuration mimics the nearest noble gas. This process often leads to the formation of stable compounds in nature and industrial applications.

• Cations: Positively charged ions, formed by losing electrons.
• Anions: Negatively charged ions, formed by gaining electrons.
• Electron gain or loss leads to a more stable, noble gas-like electron configuration.

Noble Gas Configuration

The concept of noble gas configuration describes the tendency of chemical elements to emulate the electron configuration of the nearest noble gas. Noble gases, characterized by their full valence electron shells, are inherently stable and rarely reactive.

When elements form ions, they often gain or lose electrons to achieve a configuration identical to that of a noble gas, facilitating stability. For example, the Al³⁺ ion has the same electron configuration as neon, \(1s^2 2s^2 2p^6\). Similarly, when fluorine becomes F^-, it mirrors the electron configuration of neon. This drive to achieve noble gas stability explains many ionic and chemical behaviors.

• Noble gases have full outer electron shells, making them non-reactive.
• Elements tend to form ions to achieve a similar stable electron configuration.
• This configuration minimizes energy and increases stability.

Periodic Table

The periodic table is a vital tool for understanding the properties of elements and their ions. Each element is positioned based on its atomic number, which corresponds to the number of protons in the nucleus. This arrangement not only illustrates trends in element properties but also helps predict ion formation and electron configurations.

Within the table, groups or columns signify elements with similar properties and electron configurations in their outermost shell. For example, elements in Group 1, like lithium, typically form +1 cations by losing one electron. This periodic trend assists in predicting how an element might gain or lose electrons to attain a noble gas configuration.

• Arranged by atomic number, showing periodic trends.
• Reflects similar properties within groups/columns.
• Helps predict ion formation and electron configurations based on position.

Chemical Elements

Chemical elements are pure substances that consist entirely of one type of atom, identifiable by their specific number of protons. They are the building blocks of matter and constitute the periodic table. Elements can form ions by accepting or donating electrons, a characteristic that significantly influences their chemical behavior and reactivity.

For instance, lithium, with three protons, often forms a Li⁺ ion by losing its lone outer electron. This alters its behavior and allows it to engage in chemical reactions to form compounds. Understanding these elemental traits is essential for comprehending broader chemical reactions, material science, and molecular interactions.

• Defined by their unique number of protons, unique chemical identity.
• Participate in forming ions by losing or gaining electrons.
• Their ability to ionize guides their chemical behavior and reactivity.