Naming Elements with Z>100

Transcript

0:00Introduction

Hello everyone! Okay, one small puzzle before we start. Here is a strange word for you: ununquadium. It sounds like a spell from a fantasy film, right? But it is a real chemistry name, the temporary name of an element. Do not worry if it means nothing to you yet. By the end of this video, you will read names like this in a few seconds, and build one for any element whose atomic number, Z, is greater than one hundred, just as the title says. And these names do come up in JEE as quick questions. So, let's begin.

0:36Temporary names from the atomic number

So, first, the capital letter Z on screen. Z is the atomic number of an element, the number of protons in its nucleus, okay? Now, for elements with Z greater than one hundred, that is the greater-than sign you see, IUPAC gives a temporary name, made directly from the digits of the atomic number. IUPAC is the international union that sets the naming rules of chemistry. Temporary, because later the element gets a permanent name; you will meet two of those in our first example. Right? And how is the name built? It is really simple. Each digit of Z is changed into a short root, the roots are written side by side, and at the end we add the letters i, u, m, the ium in quotation marks on screen. Got it? And the symbol? Take just the first letter of each root. So three digits give three roots, and a three-letter symbol, with only the first letter written as a capital. Clear?

1:36Ten roots, one for each digit

Alright, now the ten roots, one for every digit. Zero is nil, one is un, two is bi, three is tri, and four is quad. Say them with me: nil, un, bi, tri, quad. Okay? Now, before I show the next line, let me ask you this. Think of a shape with five sides. What do you think the root for five will be? Pent, yes, exactly, as in pentagon! So five is pent, six is hex, seven is sept, eight is oct, and nine is enn. Ten digits, ten roots. With me? Now here is a topper's trick for remembering them. Most of these roots are hiding in words you already know: bi in bicycle, tri in triangle, quad in quadrilateral, pent in pentagon, hex in hexagon, and oct in octagon. So you already know six of the ten! That leaves only four to learn by heart: nil for zero, un for one, sept for seven, and enn for nine. Four little roots, two minutes of practice, and you are done. Right?

2:42Two spelling rules, and a common trap

Now, two small spelling rules, and this is exactly where students lose easy marks. Suppose the last root of a name is bi, and we add ium. We would get b, i, i, u, m, with two i's side by side. Let me ask you: does that look right to you? No, it does not! The i of bi is dropped before ium. So bi plus ium becomes bium, with only one i. The arrow on screen means becomes, and the brackets show the wrong spelling to avoid, okay? It is the same story with tri. Tri plus ium becomes trium, again with just one i. Clear? The second rule is about enn, the root for nine. If enn comes just before nil, we would get three n's in a row. So enn drops one n, and enn plus nil becomes ennil. Right? But careful, these are the only drops. When un comes before nil, nothing is dropped: un plus nil gives unnil, with two n's. Many students write it with a single n and lose the mark. Don't do that, okay?

3:53Example 1: names and symbols for elements 101 and 104

Let's put it to work. Give the IUPAC name and symbol for Z equals one hundred and one, and for Z equals one hundred and four. Pause the video and try it first. Done? Okay, let's check. One hundred and one has the digits one, zero, one. So the roots are un, nil, un, and then we add ium. So the name is unnilunium. And look, un before nil keeps both n's, just as we said. Right? For the symbol, take the first letter of each root: u, n, u. Capital U, then small n, small u, so the symbol is U n u, with only the first letter a capital. And in brackets, the permanent name it has today: mendelevium. Now one hundred and four. This time, you do it in your head. The digits are one, zero, four. What is the name, and what is the symbol? Un, nil, quad, plus ium, which gives unnilquadium, very good! Quad for four, as in quadrilateral, remember? And the symbol is U n q, from the first letters of un, nil and quad. This element is now named rutherfordium. See how quick that was? Name and symbol in a few seconds, without memorising any list of elements.

5:21Example 2: ununquadium (114), its period, block and group

Now the harder one. Element one hundred and fourteen has been named flerovium. Give its systematic name, and its position in the periodic table. Pause the video and try it. Here is a hint: use the rules for periods, groups and blocks; the figure shows the blocks of the table. Done? Okay, let's check, the name first. The digits are one, one, four, so the roots are un, un, quad, plus ium. Ununquadium, and in brackets, its symbol, U u q, from the first letters of the roots. Hey, remember our strange word from the start? This is it! Ununquadium is simply element one hundred and fourteen. So the mystery is solved. Now the position. We need its electron configuration, shown on screen. The R n in square brackets is the radon core, the eighty six electrons of radon. Then five f fourteen, six d ten, seven s two, and seven p two; the small raised numbers count the electrons. Check: eighty six plus fourteen plus ten plus two plus two gives one hundred and fourteen. So it all adds up. First, the period. The period is the highest value of n, the principal quantum number, in the configuration. Here the highest is seven. The double arrow on screen means therefore, so this is period seven, the bottom row of the main table in the figure, just above the separate f block strip. With me? Next, the block. The last electron went into seven p, so flerovium is a p block element, on the right of the figure. Now the group. Seven s two and seven p two make four outer electrons. So it is in group four, right? No, no, careful, that is exactly the trap! For the p block, the group is ten plus the electrons in n s and n p, here seven s and seven p. So ten plus the bracket, two plus two, gives fourteen. Flerovium sits in period seven, group fourteen. Got it?

7:31Quick revision: digit roots, ium ending, spelling rules

So, quick revision. First, change each digit of Z into its root, write the roots side by side, and add ium; the symbol is their first letters. Second, the ten roots: nil, un, bi, tri, quad, pent, hex, sept, oct, enn. And third, the spelling rules: bi and tri lose an i before ium, and enn loses an n before nil. Now go and try the two practice problems on this page. You will find them easy, I promise. All the best!