The periodic table. The periodic table organizes the elements by atomic number. Remember that the atomic number of an element is unique to that element and represents the number of electrons in that element. We can predict an element's chemical properties based on where it is on the periodic table. Russian chemist Dmitry Mendelayev is considered the father of the periodic table because he was able to predict elements and their properties that had not been discovered yet. Other scientists at the time had created a similar organization, but Mendelayev was the first to leave empty spaces, predicting the later discovery of those elements that would fit into the table. That picture is a picture of his original periodic table. The first thing to notice on the periodic table is the group numbers at the top. Groups are vertical columns on the periodic table. Groups are also called families. They are written from left to right, so the left most column is group 1, then group 2, then 3. It goes all the way to group 18. The labels A and B refer to main group elements versus transition metals. The transition metals are groups 3 through 12. And there it shows 3B, 4B, 5B, 6B. The transition metals are not part of the main group elements, and neither are the rare earth elements. Those are the ones at the bottom. Main group elements are groups 1 and 2, and then 13 through 18. They're more abundant on earth, meaning that they're more common. They make up more stuff. They also correspond to different orbitals and things that we won't discuss in regular chemistry. For now, just be able to label columns 1 through 18. Periods on the periodic table are the rows. There are only 7 periods on the periodic table. It looks like there's 9, but there's not. There's only 7. The bottom ones, the bottom 2 rows, are actually just bumped down there to save space. So if you actually look at the atomic numbers, they'll all line up. Period 6. It goes from cesium with an atomic number of 55 to barium with 56 to lanthanum with 57. And then you go down to serium with 58. And then you can keep going across. You see that those actually just fit in there. So they're bumped down really just to save space. Most of the elements on the periodic table are metals. There's actually very few 9 metals. Going to the left of that dark line shown here with the purple arrow, those are all metals. And then to the right of that dark line shown in a blue arrow, those are the very few 9 metals that there are. Models are shiny. The scientific word for shiny is lustrous. They're also malleable, which means that you can flatten them into sheets like aluminum foil. Models are ductile. Ductile means that you can draw them into wires, make wires out of them. And they conduct heat and electricity. That's why we use metals to cook our food and our electronics and stuff. Nod metals are the opposite of metals. They do not conduct heat or electricity well. So we use them as insulation to keep things the same temperature. And we wrap them around wires to keep us from getting hurt from the electricity. They're also either powdery or liquid or gaseous at room temperature. They're definitely not shiny and malleable like metals. The color of the writing on the periodic table tells us what state it is at room temperature. Bromine and mercury are both liquids at room temperature, so they're in blue. The elements in red are all gasses at room temperature. All of the rest are solids at room temperature. We can use the trends or patterns on the periodic table to tell us information about the properties of those elements. For example, the alkaline metals in group 1 all behave the same way. So did the alkaline earth in group 2 or the halogens in 17 and the noble gases in group 18? The other black solid similarity is 2, but we're going to talk about all of that in a later video. To review, the periodic table is organized by a atomic number, which is a number of protons in an element. The up and down columns are called families or groups. There are 18 groups on the periodic table. Each family or group has similar properties. The side to side rows are called periods. There are 7 periods on the periodic table. There are trends or patterns in the periods as well, but again, we'll talk about that in another video. Most of the periodic table is made up of metals. Metals are shiny or lustrous. They conduct heat and electricity. They're malleable, meaning that you can form them into sheets like aluminum foil and they're ductile, meaning you can make them into wires. Metal loids have properties that are similar to metals and non-metals, and they separate the metals from the non-metals on the periodic table. There along that dark line, if you go back and look at that slide, there's a dark line to the right on the periodic table, and that's what separates your metals and your non-metals. The non-metals to the right of that dark line are on the right side of the periodic table. They are brittle, so they're not smooth. You can't flatten them out or anything, and they also don't conduct heat or electricity.