So for the periodic table, we can further organize the elements in terms of periods and groups. Now when we're talking about periods, we're referring to the 7 horizontal rows that start from the far left of the periodic table. So if we take a look here, we have hydrogen which is H2He, which is helium. This is our first row, so this is period 1. From lithium to neon, that's row 2 or period 2, and we can see that we have in total 7 rows on the periodic table. Now remember, here where we have this thicker black line, we're going to say in between La and Hf resides this entire row in yellow, and between Ac and Rf resides this entire bottom row that's in gray. Remember, to make the periodic table more presentable, we tend to take those 2 rows out and put them on the bottom. Now, what you also need to realize is that currently there are 7 rows of the periodic table, but the periodic table itself is not static. That means it's not going to be this way forever. In fact, some of the elements in the 7th row, such as these 4 here, they've only recently been named and placed on the periodic table, so within this century they were discovered and synthesized within labs. This means that there are 7 rows right now, but maybe in a 100 years. As our technology gets better, as we explore the universe, we may stumble upon new elements and they're going to be added to an 8th row and then maybe to a 9th row and then so on and so forth. So the number of rows is really based on our capacity to create and find new elements in the universe. So just realize that periods are rows. Currently, there are 7 of the periodic table. In the future, there may be more. Now where our periods are rows are groups are the vertical columns of the periodic table, and they can also be called series or families. Now we're going to say there are 18 groups with many of them having their own names. So when we're talking about columns, so for example, H all the way down to Fr is 1 column, Be all the way down to Ra is a column. So this goes from 1 to 18. So we're just numbering here, 8, 9, 10, 11, 12, and then 13 to 18. So there are 18 different columns known as groups, families, or series. Now we're going to say because of electron arrangements, elements in the same groups have similar chemical properties. We'll learn more about what these electron arrangements mean in much later chapters. Just realize for now, if elements are found in the same group, for the most part, they're going to have similar chemical properties.
Now some of these groups have special names. If we take a look here, what's shaded in brown, which is from lithium to fr, we call these our alkali metals. Then what's shaded in red from Be down to Ra, we call these our alkaline earth metals. Then what's shaded in green from N to Mc, these are known as our nyctogens. O to Lv, these are called chalcogens. In purple, those are named as halogens, so F to Ts. And then from He to Og, they have 2 different names. They're called our noble gases or our inert gases. So noble and inert kind of go hand in hand with each other. They were called inert gases at one point because it was believed that they were so stable that nothing would react with them, so they would be called inert. But upon further experiments, they found out that some of them are reactive and some of them do form compounds. So they have to basically, instead of saying inert gases, they said noble gases. But again, oftentimes, chemists will use them interchangeably. They'll say the noble gases are the inert gases, even though some of them are not inert. Now, the last 2 are not columns, but actual rows. So this row here, this top yellow row here, these are known as our lanthanides. Okay. And they're called lanthanides because they come right after La. And this row here that's in gray, they're right after Ac, so they're called our actinides. So these are the different names for the groups of the periodic table. So I know I presented a lot of information to you right now, but just keep in mind, we have our periods and we have our rows which are the periods, and then we have our groups which are our columns. This is how we further break down the periodic table.
