Which is better: to be steadfast and consistent or to be a colorful chameleon? This lesson compares and contrasts the main group elements and the transition metals. Then make your own decision!
The transition metals are found in groups 3 through 12 of the periodic table.
You can thank the main group elements for a lot of things. They are the major elements found in living organisms (that's you). They make up most of the Earth, solar system and even universe! And they play important roles in industry and economics. So what are these elements and what are some of their features?
Just like locations on a map, different areas of the periodic table have elements with different traits. In this lesson we are going to compare and contrast two of the largest areas on the periodic table: the main group elements and the transition metals. Both of these large regions have distinct features and qualities, but before we go into their characteristics, let's locate these regions on the table. First off, the main group elements consist of the first two columns (the hydrogen and beryllium columns) and the last six columns (the boron through helium columns). Using correct periodic table terminology, we would say these are elements found in groups 1, 2 and 13 through 18. The transition metals are found in groups 3 through 12. You may notice that we are leaving out that 'island' of elements down below. The top row of that island makes up the lanthanides and the bottom row makes up the actinides. We are leaving these out because they are neither main group elements nor transition metals.
Main Group Elements
The main group elements are by far the most abundant elements - not only on Earth, but in the entire universe. For this reason, they are sometimes called the 'representative elements.' The main group elements are found in the s- and p-blocks, meaning that their electron configurations are going to end in s or p. Remember the s- and p-blocks are responsible for providing the valence electrons, those super-important electrons that are involved in chemical bonding. Both the electron configurations and the number of valence electrons are very predictable as we move across the main group elements. Group 1 has elements with one valence electron, group 2 has elements with two, group 13 has elements with three valence electrons and so on to group 18, with eight valence electrons.
Non-metallic gases, with the exception of the noble gases, tend to gain electrons.
Let's use sodium as an example of how the main group elements are chemically predictable. Sodium, which has one valence electron, will almost always exist in one of two forms: its unstable, electrically neutral, metallic form (with the one valence electron), or in its stable, positively charged, ionic form (without that one valence electron). That's it. Just two forms of sodium. This predictability in the number of valence electrons creates predictability in chemical bonding - something you will be very thankful for later on. Who doesn't like a little consistency in chemistry?
Aside from the predictability of bonding and their high abundances, these elements couldn't be more different from each other. Because the main group elements consist of both metals and nonmetals, their physical properties are going to be quite different. For example, elements on the left (in groups 1, 2 and 13) are going to be solid, very metallic and tend to lose electrons, whereas many of the elements on the right are non-metallic gases that will tend to gain electrons. Well, the full shells of the noble gases will cause them to not want to gain electrons, but the rest of the non-metals would like to.
The transition metals are aptly named: they provide a bridge, or transition, between the main group metals and the nonmetals. They are all metals, and they are found in the d-block, meaning that their electron configurations are going to have unfilled d orbitals. These unfilled d orbitals make the elements much less predictable and consistent, which gives rise to some very interesting properties.
Let's take chromium as an example. Chromium can come in many forms depending on what it's bonded with. First, it occurs in its original, neutral, metallic form. Sometimes it will lose one electron; sometimes it will lose two; sometimes three, four, five or even six electrons! And each of these forms is a different color, ranging from dark purple to bright yellow to bright red. The transition metals are by far the most colorful and attractive in their many different forms.
Paperclips becoming temporarily magnetic after exposure to a magnet is an example of paramagnetism.
Finally, those unfilled d orbitals of the transition metals cause them to have many paramagnetic properties. As you may know from experience, paperclips are not normally magnetic; if you pick up one of them, the rest don't come with (unless, of course, they're linked together). However, if you bring a magnet near a group of paperclips, you may notice that they will temporarily act magnetic. This is an example of paramagnetism, which is when an external magnetic field will induce a magnetic field on a substance. That induced magnetic field is weak and temporary, but it exists.
So is it better to be predictable and consistent or chameleon-like, coming in many forms and colors? You decide! The main group elements have distinct and specific trends in number of valence electrons, which leads to an overall predictability when it comes to chemical bonding (something that will come in handy later on down the road). They will exist as either neutral elements or stable ions, and if they do lose or gain electrons to achieve full outer shells, it will be a gain or loss of the same number of electrons every time (depending on what is needed for full s and p shells). Transition metals, on the other hand, can lose varying numbers of electrons - if they even lose any at all! These elements with partially filled d orbitals can exhibit extremely bright colors (depending on which form they are in), and some can become temporary magnets if they're surrounded by a magnetic field.
After watching this lesson, you should be able to:
- Identify the main group elements and the transition metals
- Compare and contrast the characteristics of the main group elements and transition metals
- Define paramagnetism