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 Globe with Meridians

Chapter 3 - Classification Of Matter

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Atom Symbol

Chapter 1 - Models Of The Particulate Nature Of Matter

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Chapter 2 - Models Of Bonding & Structure

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Fire

Chapter 4 - What Drives Chemical Reactions?

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Rocket

Chapter 5 - How Much, How Fast & How Far?

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Test Tube

Chapter 6 - What Are The Mechanisms Of Chemical Change?

<ul>
	<li>Electron Affinity (EA) is the energy released when an extra electron is added to a neutral atom or molecule.</li>
	<li>Here&#39;s the reaction that represents it: X(g) + e&minus; &rarr; X&minus; (g) + EA</li>
	<li>If an element has a higher EA, it means adding an electron to it is more favorable and releases more energy.</li>
</ul>

<ul>
	<li>
	Across a Period (Horizontal)

	<ul>
		<li>As you move across a period in the periodic table, the nuclear charge (number of protons in the nucleus) increases.</li>
		<li>This leads to a stronger pull on the electrons, so when you add an electron, more energy is released.</li>
		<li>So, the trend is that EA generally increases across a period.</li>
	</ul>
	</li>
	<li>
	Down a Group (Vertical)

	<ul>
		<li>As you go down a group, you would predict that less energy is released when an atom gains an electron due to increased shielding of the nucleus.</li>
		<li>However, the data does not show a clear trend: this is true for group 1 elements but not for other groups.</li>
	</ul>
	</li>
</ul>

<ul>
	<li>For some elements, adding an electron to an atom results in a less stable electron configuration, which will reduce the energy released.</li>
	<li>For example, the drop in EA between silicon and phosphorus is due to phosphorus having a half-filled 3p sublevel, which is less stable.</li>
	<li>We don&#39;t always have accurate data for an element&#39;s EA, especially for elements with full or half-filled sublevels like beryllium, nitrogen, magnesium, manganese, zinc, and noble gases. In these cases, adding an electron is not favorable.</li>
</ul>

<ul>
	<li>A Real-World Analogy: Think of electron affinity like people getting into an elevator. If the elevator is empty (the atom doesn&#39;t have a lot of electrons), people (electrons) are more likely to get in because there&#39;s plenty of space. As more people get in, it gets crowded, and it&#39;s harder for others to join. The energy released when people get in at first is higher than when it gets crowded.</li>
	<li>Group 1 Elements: Group 1 elements are like a club with a bouncer (the nucleus) that&#39;s easily distracted. As more and more people (electrons) come into the club, the bouncer can&#39;t pay attention to everyone, so less energy is released when new people come in.</li>
	<li>Silicon and Phosphorus: Imagine two adjacent rooms, one with silicon and one with phosphorus. In the silicon room, there are seats (electron slots) evenly spread out. In the phosphorus room, the seats are clustered together. When a new person (electron) enters, they prefer to sit in the silicon room, where there&#39;s more space. The energy released in the silicon room is higher than in the phosphorus room, where the person has to squeeze in between others.</li>
</ul>

Remember, these are just analogies to help understand the concept. The actual process is governed by quantum physics and atomic interactions!

Unlocking Electron Affinity: Trends & Anomalies Explained

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Standard Level

Chemistry SL

Chapter 3 - Classification Of Matter

Unlocking Electron Affinity: Trends & Anomalies Explained

Table of content

What is electron affinity (EA)?

Trends in electron affinity

Unlock the Full Content!

Chapter 3 - Classification Of Matter

Unlocking Electron Affinity: Trends & Anomalies Explained

Table of content

What is electron affinity (EA)?

Trends in electron affinity

Unlock the Full Content!