The element with highest electron affinity will belong to:

A. Period 2, group 17

B. Period 3, group 17

C. Period 2, group 18

D. Period 2, group 1

To determine which element has the highest electron affinity among the options provided, we need to understand what electron affinity means. Electron affinity is the energy change that occurs when an electron is added to a neutral atom in the gas phase. Generally, elements that are more electronegative and are closer to having a full valence shell tend to have higher electron affinities.

Analyzing the Options

Let's break down the options one by one:

• Period 2, Group 17: This group contains halogens, specifically fluorine (F) and chlorine (Cl). Fluorine, being the most electronegative element, has a very high electron affinity because it is just one electron short of a full outer shell.
• Period 3, Group 17: This group includes elements like chlorine (Cl) and bromine (Br). While chlorine has a high electron affinity, it is not as high as that of fluorine.
• Period 2, Group 18: This group consists of noble gases, such as neon (Ne). Noble gases have complete outer shells and typically do not have a significant tendency to gain electrons, resulting in very low or even negative electron affinities.
• Period 2, Group 1: This group includes alkali metals like lithium (Li). Alkali metals have low electron affinities because they prefer to lose an electron to achieve a stable configuration.

Identifying the Element with the Highest Electron Affinity

From our analysis, we can see that the halogens in Group 17 are the most likely candidates for having high electron affinities. Among them, fluorine stands out as the element with the highest electron affinity due to its small atomic size and high electronegativity. When fluorine gains an electron, it releases a significant amount of energy, indicating a strong attraction for the added electron.

Final Thoughts

Therefore, the element with the highest electron affinity will belong to Period 2, Group 17, which is fluorine. This makes option A the correct choice. Understanding the trends in the periodic table, especially regarding electron affinity, can greatly enhance your grasp of chemical properties and reactivity.