Periodic Table: Classifications - Online Tutor, Practice Problems & Exam Prep

The periodic table classifies elements into three categories: metals, nonmetals, and metalloids. Metals, which are the most abundant, exhibit properties like luster, conductivity, opacity, and malleability. Nonmetals, contrastingly, are dull, poor conductors, and brittle. Metalloids, positioned along an imaginary staircase, display characteristics of both metals and nonmetals, functioning as semiconductors. Understanding these classifications is crucial for grasping the behavior and applications of elements in chemistry, particularly in technology, where semiconductors like silicon play a vital role.

Periodic Table: Classifications

When observing the elements of the periodic table, realize that they can be separated into three classifications. Now, the first classification has to do with all of the elements that are marked as red. And as you can see, a majority of the elements of the periodic table are red. Now, before we actually talk about these elements, realize here that these last two rows, they're actually found in between here. So from La, we actually go to Ce all the way to Lu, and then come back around to Hf. And then after Ac, we go to Th, and then we go all the way down to Lr, and then back to Rf. Typically, this row is taken out of the periodic table just to make it look better and more organized. But realize that these two last rows here on the bottom, they're actually within the periodic table. They just pull it out for appearance's sake. Now, these elements in red are called our metals. So, all these elements in red are metals.

Next, we're going to see that we have the elements in blue. So H over here, which stands for hydrogen, is all by itself, but then all the other blue ones are found on the far right here. So these elements that are on the right side of the periodic table, majority-wise, they are our nonmetals. And then finally, we have those in green. Now, to help us remember where those in green are, imagine that there is an invisible staircase. Now, whatever periodic table that you might be using as a sheet, try to color in this staircase that's in dark black lines here on our example of the periodic table. It'll help you remember where these elements in green are located. So there's this invisible staircase starting from B and it goes all the way to At. So, these are on the staircase, these five elements. Then, below the staircase are these two elements, Ge and Sb. So in total, we have seven of these green elements. These green elements are called our metalloids. So just remember, we have elements of the periodic table. They can be thrown into three classifications: metals, nonmetals, and metalloids. Now that we know these three classifications, let's continue onward and let's talk a little bit more about each one.

Periodic Table: Classifications

Now the metals represent the largest classification for elements on the periodic table. We can see a lot more elements in red than in either blue or green. So they greatly outnumber the nonmetals and metalloids. Now, with these metals come metallic properties, and these metallic properties can be explained through physical properties.

For the first physical property of a metal, we have here, this piece of metal. And what we're trying to convey in this image is that metals possess a luster. When we're talking about luster, we're talking about how shiny they are. Metals tend to be extremely shiny. For the next one, we have 2 wires and between them we have electricity. What this is trying to tell us is that metals are conductors, good conductors. So we're talking about their conductivity. When we refer to conductivity, we're talking about how we're able to run a current of electricity through any typical metal. Later on, we'll learn about why that is when it comes to the surface of metals. But for now, just realize that metals are good conductors of electricity.

For the next one, we're gonna say that metals are opaque. Opaque just means that you cannot see through them, they're not transparent. And then finally, another great physical property for metals is that they are malleable. Now, if we're talking about malleability, that means that we can hammer them into different shapes or into thin sheets without them breaking apart. Okay? So, if you've seen Renaissance movies, knight movies, you might see the blacksmith hammering away at a sheet of metal. That can only happen with metals. Metals are highly malleable. You can flatten them into thin sheets without having to worry about them crumbling and falling apart.

So again, when it comes to metals, they represent the largest classifications and these are the most important physical properties associated with them. Now that we've looked at metals, let's move on to the other classifications of the periodic table.

Periodic Table: Classifications Example 1

So here in this example question it says, "Which of the following elements has physical properties most similar to barium?" So we have carbon, which is represented by the symbol C, calcium, which is Ca, arsenic, which is As, xenon, which is Xe, and chlorine, which is Cl. Now, to understand which one has physical properties similar to barium, we need to know the classification of barium. Is barium a metal, a nonmetal, or a metalloid?

If we go up here, we've highlighted the element barium in black, and then the other five choices in blue. We can see here that barium is shaded red, so barium represents a metal. Therefore, we're looking for another element that is a metal because then they would share similar physical properties, such as opaqueness, malleability, and conductivity. Now, calcium looks like the only other one that's red. Right? So calcium is our metal. Arsenic is a metalloid because it's shaded green. Carbon, chlorine, and xenon are nonmetals because they're shaded blue. So coming back down to our question, we see that calcium is our answer, so option B would be the correct choice.

Just remember, when they're giving you an element and asking you to determine which one has similar physical properties, look for the classification of the element. Is it a metal, a nonmetal, or metalloid? Use that to guide you to the right answer.

Periodic Table: Classifications

So nonmetals represent the second largest classification for elements. So they're the ones shaded in blue like we said up above. Now, a key way to remember the physical properties of nonmetals is by comparing them to metals. Just remember here that nonmetals tend to have the opposite trend of metals when it comes to their physical properties. Metals have a luster; they're shiny. Nonmetals are dull. Metals are good conductors, but nonmetals are poor conductors. Metals are opaque because they're not see-through, but nonmetals, some of them are transparent and see-through. And then finally, we said that metals have malleability where we can hammer them without them falling apart. The opposite of being malleable is being brittle. If you were trying to hammer some nonmetals, they would literally crumble in your hands. So just remember, if you can remember the physical properties of metals, nonmetals are basically the opposite trend.

Periodic Table: Classifications

Now we've finally reached our 3rd classification, the metalloids. Now the metalloids, we're going to say, they have characteristics of both metals and nonmetals, and because of this, we call them semi metals or semiconductors. Now we're going to say here that the metalloids lie on an imaginary staircase starting from boron, which is B, to astatine, which is At. So if you come back up here to our periodic table, remember those in green represent our metalloids. So from boron all the way down to astatine, they lie on the staircase, above the staircase, and then below the staircase we have Ge, which is germanium, and Sb, which is antimony. So here we have 7 metalloids. We're going to say here that they act as a border with the metals lying to the left, and most of the nonmetals lie to the right. Remember, on the periodic table, hydrogen is in the top left corner, but then all the rest of the nonmetals were here on the right side. Okay. So most of the nonmetals are found on the right side except for hydrogen, which is on the far left over there.

Now, here it says, which of the following is a metalloid for this example question? So out of the choices that we saw up above, go back up, we have what? We have boron, silicon, arsenic, tellurium, astatine, germanium, and antimony. So these are the names for these different types of metalloids. Again, we'll get to names and symbols later on, but realize these are our 7 metalloids. Now based on our options, only A, as we can see all the choices, so we have A as the only option because here we have Sb, Pb, and C. The other 4 are not metalloids. Now, Si stands for silicon. You might have heard of that term when it comes to Silicon Valley. So we know that Silicon Valley exists in California. It's a hub for major tech companies, in the country.

So it's a place of innovation and technology, but Silicon Valley isn't named after those tech companies. In actuality, it's named after original settlers there who were developing silicon chips. So that's where the name Silicon Valley comes from. Now these silicon chips are incredibly important because they're found in so many of our technology. They're found within our computers, our laptops, even our phones. And the reason for this is because silicon is a metalloid. It works as a semi-metal or semiconductor. So it's the ideal type of element that can function properly within all of these pieces of technology. So again, you might have heard of Silicon Valley, you've definitely heard of different tech companies, you know what microchips are, so this is real day applications that are based in chemistry, and that's going to happen from time to time. You might think something is boring but then realize that, oh, it has a real-world use that you benefit from every day. So just remember, when it comes to the classifications of the periodic table, we have our metals, our nonmetals, and, of course, our metalloids.

Here’s what students ask on this topic:

What are the three main classifications of elements on the periodic table?

The three main classifications of elements on the periodic table are metals, nonmetals, and metalloids. Metals, which are the most abundant, exhibit properties such as luster (shininess), high conductivity, opacity, and malleability (ability to be hammered into thin sheets). Nonmetals, in contrast, are typically dull, poor conductors of electricity, and brittle (easily broken). Metalloids, which are positioned along an imaginary staircase on the periodic table, display characteristics of both metals and nonmetals, making them useful as semiconductors in technology. Understanding these classifications helps in grasping the behavior and applications of different elements in chemistry.

What are the physical properties of metals?

Metals exhibit several key physical properties. They have luster, meaning they are shiny. They are good conductors of electricity, allowing electric current to pass through them easily. Metals are also opaque, meaning they are not transparent. Additionally, metals are malleable, which means they can be hammered into thin sheets without breaking. These properties make metals useful in a variety of applications, from electrical wiring to construction materials.

How do the physical properties of nonmetals compare to those of metals?

Nonmetals have physical properties that are generally opposite to those of metals. While metals are shiny (luster), nonmetals are dull. Metals are good conductors of electricity, but nonmetals are poor conductors. Metals are opaque, whereas some nonmetals can be transparent. Lastly, metals are malleable, meaning they can be hammered into thin sheets, while nonmetals are brittle and will crumble if hammered. These contrasting properties help in distinguishing between metals and nonmetals on the periodic table.

What are metalloids and where are they located on the periodic table?

Metalloids are elements that exhibit properties of both metals and nonmetals, making them useful as semiconductors. They are located along an imaginary staircase on the periodic table, starting from boron (B) to astatine (At). This staircase includes elements like silicon (Si) and germanium (Ge), which are crucial in technology, particularly in the production of semiconductors. Metalloids act as a border between metals, which are to the left, and nonmetals, which are mostly to the right of the staircase.

Why is silicon important in technology?

Silicon is important in technology because it is a metalloid, which means it has properties of both metals and nonmetals, making it an excellent semiconductor. Silicon is used in the production of microchips, which are essential components in computers, smartphones, and other electronic devices. The ability of silicon to conduct electricity under certain conditions makes it ideal for controlling electrical currents in these devices, leading to its widespread use in the tech industry, particularly in places like Silicon Valley.