Question

Use electron configuration notation to explain why aluminum, Al, and gallium, Ga, have similar chemical properties even though gallium has \(d\) electrons but aluminum does not.

Short answer

Aluminum (Al) and gallium (Ga) have similar chemical properties due to their similar valence electron configurations. Both Al and Ga have 3 valence electrons (2 in the s orbital and 1 in the p orbital) in their outermost shells, which are responsible for an element's chemical properties. The presence of \(d\) electrons in Ga does not affect its chemical properties, as these inner electrons do not participate in chemical reactions.

Step-by-step solution

Determine the electron configurations of aluminum and gallium

First, we will find the electron configurations for both elements. The atomic number of aluminum (Al) is 13, so it has 13 electrons. The electron configuration for Al is: \[1s^2 2s^2 2p^6 3s^2 3p^1\] The atomic number of gallium (Ga) is 31, so it has 31 electrons. The electron configuration for Ga is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^1\]

Identify the valence electrons

Now we need to identify the valence electrons of both elements. Valence electrons are the outermost electrons of an atom, which are involved in chemical reactions and bonding. For aluminum (Al), the valence electrons are found in the 3s and 3p orbitals: \[3s^2 3p^1\] For gallium (Ga), the valence electrons are found in the 4s and 4p orbitals, ignoring the 3d electrons as they're considered inner electrons and don't participate in chemical reactions: \[4s^2 4p^1\]

Explain the similarity in chemical properties

The similarity in chemical properties between aluminum (Al) and gallium (Ga) can be explained by their similar valence electron configurations. Both Al and Ga have 3 valence electrons (2 in the s orbital and 1 in the p orbital), which means they will have similar electron configurations in their outermost shells. Since valence electrons are responsible for an element's chemical properties, it can be concluded that aluminum (Al) and gallium (Ga) have similar chemical properties, despite gallium having \(d\) electrons, as these inner electrons do not participate in chemical reactions.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons in an atom and play a pivotal role in determining its chemical behavior, including the types of bonds it can form and its reactivity. They are essential in understanding how elements interact in chemical reactions. For instance, elements with similar valence electron configurations tend to exhibit similar chemical properties.

Take aluminum (Al) and gallium (Ga) as examples. Aluminum has the electron configuration \[1s^2 2s^2 2p^6 3s^2 3p^1\] with the valence electrons housed in the 3s and 3p orbitals, represented as \[3s^2 3p^1\]. Gallium, on the other hand, has the electron configuration \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^1\], with its valence electrons in the 4s and 4p orbitals, \[4s^2 4p^1\]. Despite gallium having additional 3d electrons, these are considered core electrons and do not typically participate in bonding, leaving both elements with three valence electrons.

This similarity in the distribution of valence electrons explains why Al and Ga might form similar bonds and hence have similar chemical properties.

Chemical Properties

The chemical properties of an element describe how it interacts with other substances, the kinds of chemical bonds it forms, its reactivity, and other behaviors in chemical processes. Elements are distinguished by their atomic numbers, but it's their electron configuration, specifically the valence electrons, that largely dictates their chemical characteristics.

As we see from the example of aluminum and gallium, elements do not need to have the same atomic size or number of electrons to share chemical properties. The key factor is the number and arrangement of valence electrons. Aluminum and gallium both have three valence electrons, which determines how they will bond with other elements. For instance, both tend to form +3 ions in ionic compounds and are likely to form covalent bonds with elements that need three additional electrons to complete their valence shells, such as nitrogen in aluminum nitride (AlN) and gallium nitride (GaN).

Periodic Table Trends

The periodic table is a comprehensive chart that organizes elements according to increasing atomic number and recurring chemical properties. Periodic trends are patterns observed within the periodic table that illustrate different aspects of an element's characteristics.

Some key trends include the increase of atomic size from top to bottom within a group and the decrease from left to right across a period. These trends are predictable changes in the chemical and physical features of the elements and can be explained by variations in electron configurations as one moves through the table.

When considering our previous examples of Al and Ga, even though gallium lies further down on the periodic table in the same group as aluminum, they share the same group valence electron configuration, contributing to their analogous chemical properties. However, specific trends like ionization energy, electronegativity, and atomic radius also influence the unique ways in which each element behaves. Understanding these periodic trends helps us predict how an element may react or what kinds of compounds it could form.