How many electrons does an atom of each of the following elements need to gain to achieve a noble gas configuration? By gaining that many electrons, which noble gas configuration is achieved?
(b) Iodine

Verified step by step guidance

1. Determine the group number of iodine in the periodic table. Iodine is in Group 17 (halogens), which means it has 7 valence electrons.
2. Recall that atoms achieve a noble gas configuration by having a full octet (8 valence electrons) in their outermost shell. Iodine needs to gain electrons to complete its octet.
3. Calculate the number of electrons iodine needs to gain to reach 8 valence electrons. Since iodine has 7 valence electrons, it needs to gain 1 electron.
4. Identify the noble gas configuration iodine will achieve after gaining 1 electron. By gaining 1 electron, iodine will have the same electron configuration as xenon (Xe), the noble gas in Period 5.
5. Summarize: Iodine needs to gain 1 electron to achieve a noble gas configuration, specifically the configuration of xenon (Xe).

Key Concepts

Noble Gas Configuration

Noble gas configuration refers to the electron arrangement of noble gases, which have full outer electron shells, making them stable and unreactive. Atoms tend to gain, lose, or share electrons to achieve this stable configuration, typically resembling the nearest noble gas in the periodic table.

Electron Affinity

Electron affinity is the energy change that occurs when an atom gains an electron. Elements with high electron affinity tend to gain electrons easily, which is crucial for understanding how many electrons an atom like iodine needs to gain to reach a noble gas configuration.

Periodic Table Trends

Periodic table trends, such as electronegativity and ionization energy, help predict how elements will behave in terms of gaining or losing electrons. For example, elements in Group 17, like iodine, typically gain one electron to achieve a stable noble gas configuration, which in this case is that of xenon.