Which ionic compound is expected to form from combining the following pairs of elements? (d) aluminum and selenium.

Verified step by step guidance

Identify the charges of the ions formed by each element. Aluminum (Al) typically forms a cation with a charge of +3, denoted as Al^{3+}. Selenium (Se) typically forms an anion with a charge of -2, denoted as Se^{2-}.

Determine the ratio of cations to anions needed to balance the overall charge of the compound. The goal is to have the total positive charge equal the total negative charge.

To balance the charges, find the least common multiple of the charges. The least common multiple of 3 and 2 is 6.

Calculate the number of each ion needed to achieve charge balance. You will need 2 Al^{3+} ions to provide a total positive charge of +6, and 3 Se^{2-} ions to provide a total negative charge of -6.

Write the formula of the ionic compound by combining the ions in the ratio determined. The formula is Al_2Se_3, indicating two aluminum ions for every three selenium ions.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

55s

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ionic Bonding

Ionic bonding occurs when atoms transfer electrons to achieve full outer electron shells, resulting in the formation of charged ions. Metals, like aluminum, tend to lose electrons and form cations, while nonmetals, such as selenium, gain electrons to form anions. The electrostatic attraction between these oppositely charged ions leads to the formation of ionic compounds.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial in determining how an element will react chemically. For aluminum, which has three valence electrons, it typically loses these electrons to form a +3 cation. Selenium, with six valence electrons, tends to gain two electrons to achieve a stable octet, forming a -2 anion.

Chemical Formula of Ionic Compounds

The chemical formula of an ionic compound reflects the ratio of the ions that combine to achieve electrical neutrality. In the case of aluminum and selenium, the aluminum ion (Al^3+) and the selenium ion (Se^2-) combine in a 3:2 ratio to form the compound aluminum selenide, represented as Al2Se3. This formula indicates that two aluminum ions balance three selenium ions to maintain charge neutrality.

Recommended video:

Guided course

02:11

Ionic Compounds Naming

Related Practice

Textbook Question

Predict the chemical formula of the ionic compound formed between the following pairs of elements: (b) Mg and O (c) Zn and Cl

views

rank

Textbook Question

Predict the chemical formula of the ionic compound formed between the following pairs of elements: (d) Li and O.

views

Textbook Question

Which ionic compound is expected to form from combining the following pairs of elements? (a) calcium and nitrogen (b) cesium and bromine (c) strontium and sulfur

Textbook Question

Write the electron configuration for each of the following ions, and determine which ones possess noble-gas configurations: (a) Be2+, (b) Mn2+, (c) Cd2+, (d) Fe3+, (e) Tl+, (f) At-.

Textbook Question

(a) Is lattice energy usually endothermic or exothermic?

Textbook Question

(b) Write the chemical equation that represents the process of lattice energy for the case of NaCl.