What is Electron Affinity?

Summary

This transcript explores the concept of electron affinity, illustrating it through the analogy of Mr. Tom purchasing a cell phone. It defines electron affinity as the energy released when an electron is added to a gaseous atom, exemplified by chlorine, which releases energy upon gaining an electron. The discussion highlights that non-metals typically exhibit higher electron affinities compared to metals, and explains periodic trends: electron affinity increases across a period due to decreased atomic size and decreases down a group as atomic size increases, making the added electron further from the nucleus.

Takeaways

• 😀 Electron affinity refers to the energy released when an electron is added to a gaseous atom, forming a negative ion.
• 😀 The term 'affinity' means love; thus, electron affinity indicates an atom's tendency to gain electrons.
• 😀 Chlorine, for example, has a high electron affinity because it requires one additional electron to complete its octet.
• 😀 When an atom gains an electron, it loses energy, which is quantified as its electron affinity, typically expressed in kilojoules per mole.
• 😀 A negative value for electron affinity indicates that energy is released into the surroundings, signifying an exothermic reaction.
• 😀 Higher electron affinity means an element easily gains electrons and releases more energy; lower electron affinity means the opposite.
• 😀 Non-metals generally exhibit higher electron affinities compared to metals, which have lower electron affinities.
• 😀 Electron affinity trends can be illustrated with analogies, such as proximity to heat; atoms closer to their nucleus exhibit higher affinities.
• 😀 Electron affinity increases across periods in the periodic table as atomic size decreases and the nucleus attracts electrons more effectively.
• 😀 Conversely, electron affinity decreases down groups as atomic size increases, moving injected electrons further from the nucleus.

Q & A

What is electron affinity?

Electron affinity is the energy released when an isolated gaseous atom gains an electron to form a negative ion.

How does electron affinity relate to energy?

When an atom gains an electron, it releases energy, which is termed electron affinity. This process is exothermic, meaning it releases heat.

What does the negative sign in electron affinity indicate?

The negative sign indicates that energy is lost to the surroundings during the process of gaining an electron.

Why do non-metals generally have higher electron affinity?

Non-metals have higher electron affinity because they readily gain electrons and release significant energy.

What is the trend of electron affinity across a period in the periodic table?

Electron affinity generally increases across a period due to the decrease in atomic size, which allows the added electron to be closer to the nucleus.

What happens to electron affinity as you move down a group in the periodic table?

Electron affinity generally decreases down a group because the atomic size increases, placing the added electron further from the nucleus.

Can you give an example of an element with high electron affinity?

Chlorine is an example of an element with high electron affinity, as it has a strong tendency to gain an electron.

What distinguishes higher electron affinity from lower electron affinity?

Higher electron affinity means an element readily gains electrons and releases a lot of energy, while lower electron affinity means an element does not gain electrons easily and releases less energy.

How does the concept of heat energy relate to electron affinity?

The concept of heat energy relates to electron affinity in that gaining an electron releases heat to the surroundings, making the process exothermic.

What is the significance of electron affinity in chemical reactions?

Electron affinity is significant because it helps predict how atoms will interact, especially in forming negative ions and understanding reactivity patterns in elements.