Arrange the following groups of atoms in order of increasing size. a. Te, S, Se b. K, Br, Ni c.

Arrange the following groups of atoms in order of increasing...

Key Concepts

Atomic Radius

The atomic radius is a measure of an atom's size, usually defined as the distance from the nucleus to the boundary of the surrounding cloud of electrons. It is influenced by the number of electron shells and the effective nuclear charge acting on the outermost electrons.

Periodic Trends

Periodic trends refer to the regular changes in the properties of elements, such as atomic size, as you move across a period or down a group in the periodic table. These trends are primarily determined by the increase in electron shells and the rise in effective nuclear charge, which in turn affect how tightly electrons are held and influence the overall atomic size.

Transcript

00:01 So to show you the trend with size, i'm going to very roughly draw out a little sketch of the prior table.

00:12 So as we go from left to right, size increases.

00:28 And this is because the number of protons are increasing as we go from left to right, which means there is a greater effective nuclear charge.

00:39 So over here on this side, the protons in the nucleus are able to tighter, more tightly pull in the electrons.

00:49 Side, so they're pulling them in closer, which means the overall size is smaller.

00:55 So size increases from right to left.

00:58 It also increases from up down because down here we've got a lot more electrons that are being added to larger shells.

01:10 So the nucleus can't attract them as tightly, so the overall atom is larger.

01:16 Okay, so knowing these trends, we can go about answering the question.

01:27 So for t -e, s, and s -e, looking at your periodic table, these elements are all in the same column, different rows.

01:35 So the row with the greatest electrons in the outermost shell is going to be the largest, which if you look at your periodic table, that is t .e.

01:46 And then you can also see that sulfur is in the smallest row, row three, so it will have the least electrons, which is why tillerium is going to be the largest.

02:07 You can also write it like this if that's easier to understand.

02:19 So now we're looking at these.

02:23 And if you go back to your table, you'll see that they are in the same row in different columns...

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