Question

Using the periodic table, predict the charge of the most stable ion of the following elements: \((\mathbf{a}) \mathrm{Li},(\mathbf{b}) \mathrm{Ba},(\mathbf{c})\) Po,(d) I, \((\mathbf{e})\) Sb.

Short answer

Li: +1, Ba: +2, Po: -2, I: -1, Sb: -3.

Step-by-step solution

Understanding Ion Charges from Group Numbers

Elements in groups 1 and 2 lose electrons to form positively charged ions, corresponding to their group number. Elements in groups 15, 16, and 17 gain electrons to form negatively charged ions making a total of 8 electrons in their outer shell.

Predicting the Charge of Li

Lithium (Li) is in group 1 and will lose 1 electron to achieve a stable electronic configuration. This results in a +1 charge: Li → Li⁺ + e⁻.

Predicting the Charge of Ba

Barium (Ba) is in group 2. It will lose 2 electrons to become stable, which results in a +2 charge: Ba → Ba²⁺ + 2e⁻.

Predicting the Charge of Po

Polonium (Po) is often in group 16. It typically gains 2 electrons to achieve a full outer electron shell, resulting in a -2 charge: Po + 2e⁻ → Po²⁻.

Predicting the Charge of I

Iodine (I) is in group 17. It usually gains 1 electron to complete its valence shell, resulting in a -1 charge: I + e⁻ → I⁻.

Predicting the Charge of Sb

Antimony (Sb) is in group 15. It commonly forms a -3 charge by gaining 3 electrons: Sb + 3e⁻ → Sb³⁻. However, Sb can also exhibit a +3 charge depending on the context and oxidation state.

Key concepts

Periodic Table

The periodic table is a systematic arrangement of all known chemical elements. These elements are organized by increasing atomic number and are grouped into vertical columns, known as "groups," and horizontal rows, called "periods." This structure helps in predicting element properties and behaviors.

Each group in the periodic table represents a family of elements with similar chemical properties. For example, elements in Group 1, also known as the alkali metals, share the tendency to lose one electron to form positive ions. On the other hand, elements in Group 17, the halogens, tend to gain an electron to form negative ions.

• Group 1: Lose 1 electron; form +1 ions
• Group 2: Lose 2 electrons; form +2 ions
• Group 16: Gain 2 electrons; form -2 ions
• Group 17: Gain 1 electron; form -1 ions

The periodic table is a powerful tool in chemistry as it helps predict how different elements will react and bond with one another.

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It is crucial for understanding how elements will interact to form ions.

Atoms want stability, and achieving a full outer electron shell is one way to reach this. When only using the periodic table to predict the most stable ion charge, knowing the electron configuration can complete the picture.

In simple terms, each element aims for a noble gas configuration—a filled outer shell which is energetically favorable. For instance:

• Lithium (Li), which loses an electron to complete its orbital resembling Helium’s configuration, turns into Li⁺.
• Iodine (I), on the other hand, gains an electron to resemble Xenon's configuration, forming I⁻.

Recognizing patterns from electron configurations allows prediction of how elements form ions and their respective charges.

Ion Stability

Ion stability refers to how likely an ion is to maintain its charge and retain electrons in its valence shell. This stability is often reached when an ion achieves an electron configuration similar to that of the noble gases.

Noble gases have full outer shells, resulting in minimal reactivity and high stability. Other elements will lose, gain, or share electrons to mirror this stable, unreactive structure. For example:

• Lithium loses one electron, achieving the electron configuration of Helium, and forms a stable +1 ion.
• Polonium gains two electrons to mirror the electron configuration of Radon, resulting in a stable -2 ion.

The concept of ion stability is pivotal in predicting the behavior of elements and their ions in chemical reactions.

Element Groups

Element groups in the periodic table are vertical columns that hold elements sharing similar characteristics and valence electron numbers. This similarity leads to common trends observed in their chemical behavior. For example:

In Group 1, the alkali metals such as Lithium (Li) have one valence electron. They tend to lose this electron, forming a +1 ion.

Meanwhile, Group 2 elements, like Barium (Ba), have two valence electrons, leading them to form +2 ions.

In contrast, elements in Group 15, such as Antimony (Sb), commonly gain electrons to achieve a stable electron configuration, potentially forming a -3 charge, though they may also exhibit different charges depending on surrounding factors. Finally, Group 17 elements, like Iodine (I), readily gain an electron due to their seven valence electrons, forming a -1 ion in the process.

• Groups define predictable trends and charges.
• Similarities within groups aid in predictions and understanding element behavior.

Understanding these groups enhances our ability to predict ionic charges and chemical reactivity.