Name: Groups of the periodic table | Periodic table | Chemistry | Khan Academy
Uploaded: 2020-04-15T18:07:19.000Z
Duration: 7 min 41 s
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- [Instructor] So let's talk a little bit about groups

Now, a very simple way to think about groups

is that they just are the columns of the periodic table,

and standard convention is to number them.

This is the first column, so that's group one,

second column, third group, fourth, fifth, sixth,

seventh, eighth, group nine, group 10, 11, 12,

And I know some of y'all might be thinking,

what about these f-block elements over here?

If we were to properly do the periodic table,

everything from the d-block and p-block rightwards,

and make room for these f-block elements,

but the convention is is that we don't number them.

But what's interesting, why do we go through the trouble

Well, this is what's interesting about the periodic table,

for the most part, and there's tons of exceptions,

but for the most part, the elements in the column

and that's because the elements in a column,

tend to have the same number of electrons

They tend to have the same number of valence electrons,

and valence electrons and electrons in the outermost shell,

The valence electrons, these are the electrons

which tend to be the outermost shell electrons,

and there's actually a lot of interesting exceptions

that happen in the transition metals, in the D block,

but we're not gonna go into those details.

some of the groups that you will hear about,

just wants to get to two valence electrons, like helium has,

it's not, it doesn't share as much in common

these are referred to as the alkali metals,

and hydrogen is not considered an alkali metal,

Now why do all of these have very similar reactions?

Why do they have very similar properties?

you just have to think about their electron configurations.

So, for example, the electron configuration for lithium

you're going to go to your second shell, 2s1.

It has one electron in its outermost shell.

so once again, it has one valence electron,

So all of these elements in orange right over here,

and they're trying to get to the octet rule,

and so you can imagine is that they're very reactive,

this electron in the outermost shell, and that is the case.

These alkali metals are very very reactive,

and actually, they have very similar properties.

it's hard to find them where they haven't

Well, let's keep looking at the other groups.

these are called the alkaline earth metals.

And once again, they have very similar properties,

and that's because they have two valence electrons,

but let me write this, alkaline earth metals,

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Groups of the periodic table | Periodic table | Chemistry | Khan Academy

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