Question

The successive ionization energies for an unknown element are $$\begin{aligned} I_{1} &=896 \mathrm{kJ} / \mathrm{mol} \\ I_{2} &=1752 \mathrm{kJ} / \mathrm{mol} \\ I_{3} &=14,807 \mathrm{kJ} / \mathrm{mol} \\\ I_{4} &=17,948 \mathrm{kJ} / \mathrm{mol} \end{aligned}$$ To which family in the periodic table does the unknown element most likely belong?

Short answer

The unknown element most likely belongs to Group 2 - the alkaline earth metals family, as it has 2 valence electrons indicated by the significant jump in ionization energy between \(I_2\) and \(I_3\).

Step-by-step solution

Identify the significant jump in ionization energy

The first step involves identifying where the significant jump in ionization energy occurs. Comparing the given ionization energy values, we can see that the jump between \(I_2\) and \(I_3\) is greater than the others.

Determine the number of valence electrons

As there is a considerable increase in ionization energy after the second ionization, it indicates that we have removed the valence electrons after the second ionization. Therefore, our unknown element must have 2 valence electrons.

Identify the family in the periodic table

Now that we know that the unknown element has 2 valence electrons, we can identify the family in the periodic table it most likely belongs to. Elements with 2 valence electrons belong to the family of alkaline earth metals, which is Group 2 in the periodic table. In conclusion, the unknown element most likely belongs to Group 2 - the alkaline earth metals family.

Key concepts

Ionization Energy

Ionization energy is a vital concept in understanding how elements interact with each other. It represents the amount of energy required to remove an electron from an atom. This concept helps us identify how stable an atom is and how it may react chemically. For instance, the first ionization energy refers to the energy needed to remove the first electron, while the second ionization energy applies to the removal of a second electron, and so on.

When considering successive ionization energies, a significant increase typically indicates the removal of electrons from a filled or stable electron shell, which is closer to the nucleus. For instance, in the example provided, a sizable leap is noticeable between the second and third ionization energies. Such a jump signifies that the element lost its valence electrons after the second ionization, hinting at the presence of two valence electrons initially. This pattern is critical for determining the chemical family's group to which the unknown element belongs.

Valence Electrons

Valence electrons are the electrons located in the outermost shell of an atom. They are crucial in determining how an element will bond and interact with other elements. An element's reactivity is often driven by its desire to attain a full valence shell, typically achieved by losing, gaining, or sharing electrons.

In the case of the unknown element, the identification of a large jump between the second and third ionization energy indicates that it initially has two valence electrons. Once these electrons are removed, the atom reaches a more stable electronic configuration, suggesting that it now has a full inner shell. Recognizing the number of valence electrons is key to understanding the chemical behavior and placement of an element in the periodic table, placing elements with similar valence electrons into specific families or groups.

Alkaline Earth Metals

The alkaline earth metals consist of elements in Group 2 of the periodic table. These elements, including beryllium, magnesium, calcium, strontium, barium, and radium, are characterized by having two valence electrons. This characteristic shapes their chemical and physical properties.

Alkaline earth metals are typically less reactive than their Group 1 counterparts, the alkali metals, but still react by losing their two valence electrons to achieve a full outer electron shell. This action results in the formation of +2 charged ions, giving rise to various stable compounds.

The periodic jump in ionization energy seen in the unknown element, specifically after the removal of two electrons, aligns perfectly with the behavior of alkaline earth metals. Therefore, based on its ionization energy pattern, the unknown element is likely to belong to this family, highlighting the vital role ionization energy and valence electrons play in predicting an element's position in the periodic table.