Question

Each of the following elements is capable of forming an ion in chemical reactions. By referring to the periodic table, predict the charge of the most stable ion of each: (a) \(\mathrm{Mg}\), (b) \(\mathrm{AI}\), (c) \(\mathrm{K},(\mathrm{d}) \mathrm{S},(\mathrm{e}) \mathrm{E}\).

Short answer

The most stable ion charges for each element are: - Mg: \(Mg^{2+}\) - Al: \(Al^{3+}\) - K: \(K^{+}\) - S: \(S^{2-}\) - O: \(O^{2-}\)

Step-by-step solution

Locate elements on the periodic table

We first locate the elements in the periodic table: (a) Magnesium (Mg) (b) Aluminum (Al) (c) Potassium (K) (d) Sulfur (S) (e) Oxygen (O)

Determine the number of valence electrons for each element

Valence electrons are the electrons in the outermost shell of an atom. The number of valence electrons of an element can be determined using the periodic table. The element's Group number indicates the number of valence electrons. (a) Mg is in Group 2, so it has 2 valence electrons (b) Al is in Group 13, so it has 3 valence electrons (c) K is in Group 1, so it has 1 valence electron (d) S is in Group 16, so it has 6 valence electrons (e) O is in Group 16, so it has 6 valence electrons

Determine the ion charge of each element

For elements in Groups 1-3, they tend to lose electrons to achieve a stable configuration (a fully occupied outermost shell). For elements in Groups 15-17, they tend to gain electrons to achieve a stable configuration. (a) Mg will lose 2 electrons to achieve a stable configuration, forming an ion with a charge of +2: \(Mg^{2+}\) (b) Al will lose 3 electrons to achieve a stable configuration, forming an ion with a charge of +3: \(Al^{3+}\) (c) K will lose 1 electron to achieve a stable configuration, forming an ion with a charge of +1: \(K^{+}\) (d) S will gain 2 electrons to achieve a stable configuration, forming an ion with a charge of -2: \(S^{2-}\) (e) O will gain 2 electrons to achieve a stable configuration, forming an ion with a charge of -2: \(O^{2-}\) Therefore, the most stable ion charges for each element are: - Mg: \(Mg^{2+}\) - Al: \(Al^{3+}\) - K: \(K^{+}\) - S: \(S^{2-}\) - O: \(O^{2-}\)

Key concepts

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom. They play a crucial role in determining how an element will react chemically. The number of valence electrons can often be determined using the periodic table.

For example, elements in Group 1 have 1 valence electron, while elements in Group 2 have 2. Elements in Group 13 have 3 valence electrons, and so on. Knowing the count of valence electrons helps in predicting how an element will interact with others, as atoms tend to gain, lose, or share electrons to reach a stable electron configuration, often resembling the nearest noble gas.

• Magnesium (Mg) in Group 2 has 2 valence electrons.
• Aluminum (Al) in Group 13 has 3 valence electrons.
• Potassium (K) in Group 1 has 1 valence electron.
• Sulfur (S) in Group 16 has 6 valence electrons.
• Oxygen (O) in Group 16 also has 6 valence electrons.

Understanding valence electrons is fundamental to grasp why elements form ions with specific charges.

Periodic Table

The periodic table organizes elements based on similar properties and recurring chemical behaviors. It’s a powerful tool in chemistry for predicting how elements will react with each other.

Elements are arranged in rows called periods and columns known as groups or families. The position of an element in a group can tell us a lot about its properties, especially its valence electrons. Groups are numbered from 1 to 18 and elements within the same group often have similar chemical properties due to having the same number of valence electrons.

• Group 1 elements, like Potassium (K), typically form +1 ions.
• Group 2 elements, such as Magnesium (Mg), tend to form +2 ions.
• Elements in Group 13, such as Aluminum (Al), usually lose 3 electrons to form +3 ions.
• Group 16 elements, including Sulfur (S) and Oxygen (O), often gain 2 electrons to form -2 ions.

By locating where an element falls in the periodic table, you can predict its behavior and stability in compounds.

Ion Charge Prediction

Predicting the charge of an ion is based on understanding the desire of atoms to reach a stable configuration, like that of a noble gas. In chemical reactions, atoms will either lose, gain, or share electrons to achieve full outer electron shells.

Generally, the number of valence electrons can guide this prediction:

• Elements with 1-3 valence electrons (such as Groups 1-3) will typically lose these electrons, resulting in positive ion charges. For example, Magnesium (Mg) loses 2 electrons to form a +2 ion, and Aluminum (Al) loses 3 to form a +3 ion.
• Conversely, elements with 5-7 valence electrons (like Groups 15-17) are more likely to gain electrons to fill their outer shell, leading to negative ion charges. Sulfur (S) and Oxygen (O) both gain 2 electrons, forming -2 ions.

Thus, understanding the balance of gaining or losing electrons helps predict the ionization behavior of elements.