Non-metals in the periodic table

The non-metals in the periodic table are greatly outnumbered by the metals. There are many negatively charged polyatomic ions, however, to make up for this. In fact, polyatomic anions are commonly found in everyday chemicals. Refer back to Table 3.4 for the names of the most common polyatomic anions. 

Problem 1.4 Would you consider Ps a metal or a non-metal in the Periodic Table of the Elements ... 

Nickel is classified as a transition metal. Transition metals are elements between Groups 2 (metals) and 13 (non-metals) in the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Nickel is closely related to iron, cobalt, copper, and zinc. These metals are close to nickel in the periodic table. 

There is, in fact, no clear-cut distinction between metals and non-metals. In the periodic table, there is a change from metallic to non-metallic properties across the table, and an increase in metalUc properties down a group. Consequently there is a diagonal around the center of the table (B, Si, As, Te) in which there is a borderline between metals and non-metals, and the metalloids are the borderline cases. Elements such as arsenic, germanium, and tellurium are semiconductors, but other elements are often said to be metalloids according to their chemical properties. Tin, for instance, forms salts with acids but also forms stan-nates with alkalis. Its oxide is amphoteric. Note also that tin has metallic (white tin) and non-metallic (gray tin) allotropes. 

Figure 21.1 Nonmetals and the periodic table. The location of all non-metals in the periodic table is shown in yellow. Symbols are given for the nonmetallic elements discussed in this chapter.

Nonmetals are the opposite of metals. Thus, while metals give cations (positive ions) nonmetals will yield anions (negative ions), which are the opposite of cations. We can predict the charge on an anion from the position of the non-metal on the periodic table. Since nonmetals are the opposite of metals, we will need to count in the opposite direction. The noble gases are zero. The next column to the left will be -1, then -2, and then -3. The nonmetals on our list should form the following anions ... 

In a compound containing a metal and a nonmetal, the nonmetal is an anion. The anionic charge of a nonmetal is predictable from the position of the non-metal on the periodic table. You begin on the far right and count towards the left until you get to the column containing the nonmetal of interest. The noble... 

The position of non-transition metals in the periodic table is shown in the following figure. 

Figure 1 shows the position of non-transition metals in the periodic table. They fall into two classes with significantly different chemistry. The pre-transition metals comprise groups 1 and 2 and aluminum in group 13. They are typical metals, very electropositive in character and almost invariably found in oxidation states expected for ions in a noble-gas configuration (e.g. Na, Mg, ... 

Situated between the solid and gaseous states as the only non-metallic element liquid at ambient temperature, bromine is sandwiched in the periodic table between the ubiquitous chlorine and the rather rare iodine. In terms of production volumes it is neither a bulk commodity chemical like chlorine, nor a speciality chemical like iodine. And commercially, bromine is beset by uncertainty. Until the 1970s, the major market forbromine was in dibromoethane - a co-additive for leaded petrol. The phase-out of lead in petrol could have spelled the collapse of the bromine industry, but alternative bromine markets developed and the industry both rationalised and flourished. However, although world bromine production continues to increase slowly, fresh environmental concerns have emerged and the industry is once more under threat. Details are given. 19 refs. 

Perhaps all the elements present in the periodic table might be excited to yield respective emission spectra by employing a huge energetic source. However, it has a serious drawback because most of the spectral lines invariably fall within the vacuum-ultraviolet region thereby rendering their critical studies rather difficult. Hence, the emission spectroscopy is exclusively limited to metals and metalloids. The non-metals, for instance Phosphorus, Sulphur, Carbon etc. are not limited to these studies. 

Figure 4.6. Blocks of the Periodic Table. The names (symbols) of the so-called blocks are indicated. In the p block two types of elements can be considered, roughly separated by the Zintl line semi-metals in the left-hand part and non-metals in the right-hand part.

So that is why an element s location in the Periodic Table - its row and column - tells us a lot about its chemical behaviour. Metals fall to the left, non-metals to the right. The column number is a predictor of the valency. As a general rule, chemical reactivity declines as one progresses down the rows... and so on. The table is the best crib sheet a young aspiring chemist, sweating through a summertime exam, could wish for. 

But it took us a very long time to figure out what this pure silicon is good for. It occupies that curious no man s land in the Periodic Table where metals (to the left) give way to non-metals (to the right). Silicon is not a metal, but it does conduct electricity - albeit poorly. It is a semiconductor. 

Carbides. As might he expecled from its position in the periodic table, carbon forms binary compounds with the metals in which it exhibits a negative valence, and binary compounds with the non-metals in which it exhibits a positive valence. A convenient classification of the binary compounds of carbon is into ionic or salt-like carbides, intermediate carbides, interstitial carbides, and cuvalent binary carbon compounds. 

From a true catalytic point of view, what is looked for are so-called synergetic effects , i.e., a reciprocal influence between two or more components so as to obtain a material whose activity exceeds that of the pure components [74]. This usually involves intimate electronic interaction between the various components so that their electronic structures become profoundly modified. It is well possible that a metal deprived of part of its valence electrons may behave as the element on its left in the Periodic Table [75]. However, the theory of synergetic effects is still in its infancy in electrochemistry. Predictions for a bimetallic catalyst with two non-interacting sites obtained by combining two metals with different adsorption energies are that... 

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