A catchy Bollywood tune begins with the phrase “While this world is made pital I am made of pure gold”. ,pital,Hindi is for brass, yellow metal You often see it on doorknobs, jars for holding water, or even sometimes in decorative items placed on shelves in your homes. The woman in the song is teasing that although brass is ubiquitous, it cannot really be a substitute for authentic gold.
Is brass on the periodic table?
On your smartphone, search for “periodic table of elements”. A monstrous creature should appear, containing rows of boxes with letters and maybe a lesser number of numbers. Each of these boxes represents an element – hydrogen (H), iron (Fe), silver (Ag), and so on. You’ll also find a number written inside each box: this is the number of protons and electrons in an atom of that element.
Protons, neutrons, and electrons are the fundamental particles that make up every element. For example, hydrogen (H) has one proton, carbon (C) has six, and iron (Fe) has 26! The size of an atom is roughly larger if it has more protons, so an iron atom is much larger than a carbon atom, which is in turn larger than a hydrogen atom, and so on.
the periodic table is atableOf All elements in the universe; In fact, the periodic table is one of many people’s most astonishing achievements, the culmination of many painstaking searches.
Now, go through the table and look for brass. If you look at Br, that’s bromine, a rather toxic liquid, not what you’re looking for. You’ll soon realize that even the brass isn’t there.
What is brass?
brass is notConsidered in the periodic table because it is not an element. It is an alloy, a mixture of elements. Brass is an alloy of copper and zinc in some percentage. Copper and zinc are both elemental metals with their own properties, but if you mix them, like you mix spices in a bowl, you can get new ‘tastes’ of the metals. In fact, you can keep experimenting and with enough tries, you might even come up with a new recipe that will surprise everyone!
For example, consider iron – present in the weight standards used by vegetable vendors. Add a pinch of carbon (C) and mix, and you get steel, which you may have seen Sunny Deol advertising as the “highest form” of strength. But then steel can rust, so add a spoonful of chromium and you get stainlessSteel, which does not rust. No wonder we use stainless steel spoons in our homes, which last for many years.
Why, empty your wallet and put the pennies on the table, and you’ll find a bunch of alloys. The gray colored coin of one or two rupees is made of stainless steel. The new ten rupee coin has a copper-tin (bronze) alloy on the outer, yellow rim; And the yellow five-rupee coin is the ubiquitous brass, which is where our story began.
Why is brass useful?
You might wonder why we use brass for so many things and not just copper. Why add a little zinc to it? This is because the copper atoms are quite large. The internal structure of copper metal is actually an array of copper atoms arranged in a neat order, like rows of trolley cars in an airport or supermarket.
But as we know from our own experiences, and sometimes accidents do happen, it is relatively easy to push an entire row of trolley cars. Because of their neat arrangement, cars do not cross each other’s paths. This is why copper is ductile: it can easily change shape under pressure, allowing us to make the copper wires that are ubiquitous in electrical transmission cables.
As it happens, the zinc atom is slightly larger than the copper one. If you go back to the periodic table, you’ll find zinc (Zn) sitting just to the right of copper (Cu). It has one more proton and is therefore slightly larger. So a few zinc atoms, in place of copper atoms, are like misshapen trolley cars that exist among otherwise neatly arranged well-ordered cars.
Add zinc to it and it can surprisingly change some of its properties. These few misshapen trolley cars obstruct the flow of the rest of the ‘copper’ trolley cars. This is not unlike a traffic jam, where a few misaligned SUVs can completely derail regular traffic. Now, it becomes very difficult to move the series of trolley cars anywhere under pressure as they all get stuck in each other. If we try to move one, we soon find that we need to exert enough force to move them all.
While traffic jams like this can really hurt on a vacation drive, material-wise it’s great: The metal has grown stronger. If you fall on the floor, if you jump or sit on it, it will not easily bend under the pressure. The same physics occurs in steel, where you jam the iron atoms with the very small carbon atoms, preventing smooth movement.
Remember the Beauty of Alloys
That’s why it’s no surprise (or maybe it Is One wonder), when we want to make utensils or durable items like door knobs, where there is a lot of roughness, we use a material that is a good survivor, and go for brass. As it happens, pure gold, as an elemental metal, is often quite soft and can deform easily under pressure.
So the next time you’re grooving to a popular Bollywood song that compares brass unfavorably to gold, remember the beauty of alloys, jam trolleys and that simple yellow metal.
Adheep Agarwal is Assistant Professor of Physics at IIT Kanpur.