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The periodic table

The periodic table organizes elements into groups and periods based on their chemical and physical properties. Elements in the same group share similar characteristics, like reactivity. The table is divided into metals, nonmetals, and metalloids, each with distinct properties. Key groups include alkali metals, alkaline earth metals, halogens, and noble gases. Created by Jay.

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  • starky sapling style avatar for user D Morales
    Why are they called "noble" gasses?
    (8 votes)
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    • old spice man green style avatar for user Matt B
      Because unlike every other atom, noble gases are too cool to undergo any sort of bonding and prefer to go solo. They are "noble" because they don't need the help of others.
      All of this is because they already have a full outer shell of electrons and are fully stable already.
      (88 votes)
  • piceratops seed style avatar for user ananya.bhattacharya
    What is the difference between alkaline metals and alkaline earth metals?
    (9 votes)
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    • leaf blue style avatar for user Manoj
      Difference between alkaline metals and alkaline earth metals:
      ~Electron configuration: Alkali metals have the electronic configuration of [Noble gas] ns1 and alkaline earth metals have, [Noble gas] ns2 electronic configuration.
      ~valance : All the alkali metals have an electron in their outermost shell and all the alkaline earth metals have two outer electrons. To achieve the noble gas configuration, alkali metals need to lose one electron (valence is “one”), whereas alkaline earth metals need to remove two electrons (valence is “two”).
      ~Reactivity: Both alkali metals and alkaline metals are very reactive. Alkali metals are more reactive than alkaline earth metals.
      ~Ionic charge: Alkali metals have +1 ionic charge in their compounds and alkaline earth metals have +2 ionic charge in compounds.
      ~Hardness: Alkali metals are very soft and they can be cut with a sharp knife. Alkali earth metals are harder than the alkali metals.
      (23 votes)
  • purple pi teal style avatar for user Siddesh Minde
    Is gallium a semi metalliod
    (6 votes)
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  • starky tree style avatar for user Max Adair
    What is the rest of the elements and what do all the symbols stand for?
    (6 votes)
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  • aqualine tree style avatar for user Kate Fug
    I notice the narrator did not select Aluminum as a metalloid. Why is Aluminum not considered to be a metalloid?
    (6 votes)
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    • leafers seed style avatar for user Travis Bartholome
      Aluminum acts as a metal; it is conductive, malleable, and ductile. So it is classified as a metal because of its actual properties, despite its position near the other metalloids in the periodic table. I have occasionally seen aluminum classified as a metalloid, though, and from what I understand this is because it does sometimes exhibit chemical properties that are metalloid-like, such as the way it bonds in some compounds. Generally, it is classified as a "post-transition metal" along with the other metals in the p-block.
      (12 votes)
  • purple pi teal style avatar for user Badge Collector
    Just out of interest if I wanted to be a scientist would I have to memorize/know the periodic table by heart?
    (5 votes)
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  • blobby blue style avatar for user 😑
    When going through my 9th grade NCERT textbook, I came across an element called ‘platina’. When I googled it, I didn’t get proper results and instead got results for platinum. Does anyone know what platina is? Thanks, Richard!
    (6 votes)
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  • scuttlebug blue style avatar for user Prisha
    Could you combine two elements to make a whole new element, or would the combination be a solution rather than a brand new element?
    (3 votes)
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    • leaf red style avatar for user Richard
      So elements are different types of atoms which are differentiated by their atomic number (the number of protons). So in practice we're not really combining elements rather atoms of different elements. Combining two atoms of different elements together depends on how much energy you put into such a collision.

      1) At low energies (think low temperatures essentially) putting together two samples composed of atoms of different elements doesn't usually create a reaction. You just get a mixture of different types of atoms. For example, if I combine hydrogen and oxygen gas together at low temperatures then I just have a vessel filled with unreacted gas.

      2) At higher energies we start creating the situation suitable for reactions to occur. Now there is enough energy to break chemical bonds and conduct a chemical reaction where the atoms of different elements can combine into a compound composed to atoms from both elements. Using the hydrogen and oxygen gas example, if we added those gases together and introduced a source of heat like a flame, they would react and combine to form water. Which as we know is a chemical compound composed of the elements hydrogen and oxygen. With a chemical reaction even though chemical bonds have been broken and reformed to create a new chemical, we haven't touched the protons in the nucleus and therefore haven't changed the elements involved. This is the most common case you will encounter in chemistry.

      3) At very high energies we can get the atoms of different elements moving so fast so that when they collide their nuclei can fuse into one larger nucleus. Since our new nucleus has a different number of protons than the original nuclei, we have created a new element different from the original two. Anytime you want to change an atom into a new element you must change the number of protons in the nucleus either by adding or removing them. This types of changes involve the nuclei of atoms and are therefore in the realm of nuclear chemistry which is a more specialized field of chemistry which is rarer to encounter. Hope that helps.
      (9 votes)
  • aqualine ultimate style avatar for user talatisaumil
    What is perhaps the easiest way to remember to periodic table
    (3 votes)
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  • blobby green style avatar for user sanjey
    why was the periodic table made or created ?
    (3 votes)
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    • purple pi purple style avatar for user Rifah Sanjida
      The periodic table was made for the chemists so that they could easily remember the properties of any element. It's not easy for anyone to keep all things in memory. You can easily guess any thing about an element by comparing with tthe other elements. So, it can be very useful for both the chemistry students and the scientists.

      I hope, you got this.... :)
      (5 votes)

Video transcript

In this video, we're going to look at the periodic table. We're going to classify the elements into groups. And so as we go through these terms, I'm going to be checking them off. The groups are the vertical columns on the periodic table. And so, if I go over here, I can see that all of these elements are in the same vertical column. So all these elements are in the same group. And we call this group 1. I can see that all of these elements are also in the same column. So all these elements are in the same group, and we call this group 2. I can continue labeling my groups. This would be group 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. And then I go back up to here, and I can see I have another vertical column, so group 13, 14, 15, 16, 17, and finally 18. So that's one way to number your groups. There is another way to number your groups, and that would be to say that group 1 is group 1A, group 2 is group 2A. And then kind of ignoring groups 3 through 12, continue on with your numbering system. So 1A, 2A-- that would make this group 3A, group 4A, group five 5A, group 6A, 7A, and finally 8A. And this second way of numbering your groups is useful when you're thinking about valence electrons. And so let's move on to the concept of periods. A period is a horizontal row on the periodic table. And so, if I look at period 1, and I just move across my periodic table, hydrogen is in the first period and so is helium. I move on to the second period, so lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. And so I can continue with numbering my periods, so this would be period 3, 4, 5, and 6. Now notice I don't have the entire periodic table on this video. I didn't have enough room, and we're not really going to talk about all of those elements anyway. So let's go ahead and focus on metals next. Let's talk about the alkali metals. When I'm talking about metals, I'm going to try to write it in red here. The alkali metals are found in group 1, or group 1A, so things like lithium, and sodium, potassium. So here are my alkali metals. The alkali metals are soft, silvery metals that are extremely reactive. And one nice thing about organizing elements into groups is elements in the same group have similar chemical properties. And so the alkali metals react in similar ways. For example, all the alkali metals will react with water. And the alkali metals turn out to be so reactive that you're not going to find them in their pure state in nature. You're not going to walk outside and find some sodium lying on the ground. They're found in nature in combination with other elements. Let's talk about hydrogen, because hydrogen is also in group 1, but hydrogen is not an alkali metal. Hydrogen is a nonmetal. So let me go ahead and draw that in green here. I will represent nonmetals in green. Hydrogen is the exception in group 1. Next, let's talk about the alkaline earth metals. You find those in group 2, or group 2A, so right in here. Things like magnesium and calcium and strontium are your alkaline earth metals. Your alkaline earth metals are reactive-- not quite as reactive as the metals in group 1, but you don't find these in the pure state, either. You find them in combination with other elements. And so once again, the alkaline earth metals are going to react in similar ways. They have similar chemical properties, and so that's, again, a convenient way of organizing the periodic table into groups. For right now, let's just go ahead and say-- groups 3 through 12-- these are all metals in here. And let's just talk about metals in general for a minute. Metals, the properties of metals. Metals are solids at room temperature, except for mercury. So here is mercury down here, which is a liquid at room temperature. Metals are very malleable, which means you can form them into different shapes. They're very workable. They're not brittle. Metals are also ductile, which means you can draw them into wires. You can form them into wires. For example, like copper. Here's copper right here. Copper wires, of course, carry current in homes. So metals are good conductors of heat and electricity. And so those are the properties of metals that most textbooks will talk about. Let's contrast those with nonmetals. Nonmetals-- if you have a solid nonmetal, those solids would tend to be brittle, not malleable like metals. Nonmetals are poor conductors of heat and electricity. So you find nonmetals in different states of matter. Let's talk about one of the nonmetals now, and that would be the halogens. Let's find the halogens on our periodic table. You find them in group 7A, or group 17, things like fluorine, chlorine, bromine. Here are your halogens right in here. Halogens are very reactive nonmetals. So they're often very colorful, very, very corrosive, and the name halogen actually means salt former. We're actually going to come back to that in the next video when we look at some electron configurations and we talk about why these things are so reactive. And so those are the halogens. Next, let's find the noble gases. The noble gases are found in group 8A, or group 18. Some of these are very famous, like helium, neon, argon, krypton. Here are your noble gases. They're colorless gases, and they're generally very unreactive. Once again, we'll talk about why in the next video when we talk about some electron configurations. There are some other nonmetals on here, which I will identify in a minute. But first I want to talk about the fact that you pretty much find metals on the left side of the periodic table. So let me go back to the red color. And you can see I have all these metals over here on the left side. And then for my nonmetals, in green, you're going to find those over here on the right side of your periodic table. The dividing line between those-- let me go ahead and draw it in there-- it's kind of a zigzag line. Let me see if I can sketch it in here. The dividing line would go something like this. We're going to go a zigzag line down our periodic table. And some of the elements that you find on this zigzag line have properties in between those of metals and nonmetals, and we call those metalloids. Let's go ahead and talk about metalloids now. Metalloids-- oid, of course, being like a metal, so it's similar to metals, but, again, the properties are in between those of a metal and a nonmetal. Some of the elements that are considered to be metalloids would be boron-- right in here-- silicon, germanium, arsenic, antimony, tellurium, and sometimes you'll see astatine listed as one. It depends on which textbook that you're looking in. So you can see that some of the elements along this zigzag line are considered to be metalloids. And there's no official, one definition for which elements are considered to be metalloids, and so you might see a little bit of a discrepancy there for some of these elements. But in general, those are the ones that are considered to be metalloids, silicon probably being the most famous one. Silicon is a semiconductor. It's a metalloid, so it's like a metal, so it does conduct electricity, but not to the same extent that a metal would. And so these intermediate properties are sometimes useful. Let's go ahead and mark some of the rest of these. These would be some other metals. And then over here on the right would be the rest of your nonmetals here. Carbon is nonmetal, nitrogen is nonmetal, oxygen is nonmetal, phosphorus, sulfur. So that's just a quick way to divide the periodic table up with some simple definitions. In the next video, we'll talk more about the electronic structure, and we'll get into definition of transition metals.