Electro-positive

The electro positive nature of silicon, coupled with its larger size and availability of the empty cf orbital affects its reactivity. 

Cerous iodates and the iodates of the other rare earths form crystalline salts sparingly soluble in water, but readily soluble in cone, nitric acid, and in this respect differ from the ceric, zirconium, and thorium iodates, which are almost insoluble in nitric acid when an excess of a soluble iodate is present. It may also be noted that cerium alone of all the rare earth elements is oxidized to a higher valence by potassium bromate in nitric acid soln. The iodates of the rare earths are precipitated by adding an alkali iodate to the rare earth salts, and the fact that the rare earth iodates are soluble in nitric acid, and the solubility increases as the electro-positive character of the element increases, while thorium iodate is insoluble in nitric acid, allows the method to be used for the separation of these elements. Trihydrated erbium iodate, Er(I03)3.3H20, and trihydrated yttrium iodate, Yt(I03)3.3H20,... 

Another reason for the priority of this metal is that in many cases the more electro-positive and morn chemically active potassium proves to be too violent... 

Basic Oxides.—It is characteristic of the metallic elements that each forms at least one oxide which will react with acids producing salts, the valency of the metal remaining unaltered. Such oxides arc termed basic oxides or sometimes merely bases. Some metals yield more than one oxide, and it is then generally observed that the oxide richer in oxygen possesses a more feebly basic character. In the case of the most electro-positive metals, for example the alkali metals, the oxides will combine with water, producing soluble hydroxides which are strongly... 

Reduction of Iron Salts to Metallic Iron.—Both ferrous and ferric salts can be reduced to the metal in a variety of ways. In solution many of them are reduced by the introduction of more electro-positive metals such as magnesium, zinc, or aluminium, as also by electrolysis. In the dry way they are reduced by heating in a current of hydrogen... 

The colloid, as usually prepared, is electro-positive in character, and may be precipitated from solution by electrolysis, by the addition of small quantities of electrolytes, or by the action of an oppositely charged colloid, such, for example, as (negative) arsemous sulphide, whereby the two electrical charges neutralise each other.7 The smallest quantities of a few electrolytes required to precipitate colloidal ferric hydroxide from solution are given in the following table —8... 

Chromates, dichromates, etc., are readily reduced, e.g. by hydro-clrloric acid (with evolution of chlorine), by sulphurous acid (ivith formation of sulphate and dithionatc), by hydrogen sulf>hide (ivith separation of sulphur), by ferrous salts, by alcohol, etc., the solution simultaneously becoming green owing to the formation of a chromic salt. The chromates of the more feebly electro-positive elements decompose w hen strongly heated, with formation of chromium sesquioxide dichromates of other metals yield normal chromates, chromium sesquioxide, and oxygen. ... 

This is a particular case of a general law because it can be seen, according to this theory, how the electro-positive or electro-negative value of the elements mutually modifies and conditions the electropositive or electro-negative value of the other elements. 

Although the silicon atom has the same outer electronic structure as carbon its chemistry shows very little resemblance to that of carbon. It is true that elementary silicon has the same crystal structure as one of the forms of carbon (diamond) and that some of its simpler compounds have formulae like those of carbon compounds, but there is seldom much similarity in chemical or physical properties. Since it is more electro-positive than carbon it forms compounds with many metals which have typical alloy structures (see the silicides, p. 789) and some of these have the same structures as the corresponding borides. In fact, silicon in many ways resembles boron more closely than carbon, though the formulae of the compounds are usually quite different. Some of these resemblances are mentioned at the beginning of the next chapter. Silicides have few properties in common with carbides but many with borides, for example, the formation of extended networks of linked Si (B) atoms, though on the other hand few silicides are actually isostructural with borides because Si is appreciably larger than B and does not form some of the polyhedral complexes which are peculiar to boron and are one of the least understood features of boron chemistry. 

Protein fibres are usually dyed with acid dyes under conditions where there will be mutual attraction between the fibre and the dye ion. The problem, therefore, is to retard the sequence of events. The mechanism of dyeing protein fibres with acid dyes is extremely complex, but it is believed that faster moving anions from the added acid temporarily occupy the electro-positive sites in the fibre, and they are replaced at a retarded rate... 

A young English scientist recently promulgated the theory that the atomic number corresponds with the electro-positive charges that form the nucleus of any atom. In other words, if the atomic number corresponds to the number of units of positive electricity that go to make up the atomic nuclei, there must be one electron or negative unit. Thus, the hydrogen atom contains one electron, the helium atom two electrons, lithium three electrons and so on through the entire list. 

As first noted by Seki and coworkers [12] and later confirmed by Kahn and coworkers [13] even in the most simple cases this approximation does not hold. When saturated hydrocarbons, which are among the least reactive molecules in organic chemistry, are deposited onto the most inert metal, Au, a reduction of the work function on the order of 1 eV can be seen. It is interesting to note that this work function lowering has about the same amount encountered when an electro-positive element like Cs is deposited on a metal surface. These changes of the work-function even in the absence of any chemical interaction (like charge transfer or bond formation) are attributed to the formation of an interface dipole located between the molecule and the metal substrate. 

Silicon is less electronegative (more electro positive). 

An acid is a compound of an electro-negaiim elemeni or residue with ky drogen xdhich hydrogen it can part wUh in exchange for an electro-positive Yemeni urithoui formation of a base. An acid may also be defined aa a compound body which evolves toater by its action upon pure caustic potash or soda. 

Compounds consisting of two elements, or of an element and a radical only, binary compounds, are designated by compound names made up of the name of the more electro-positive, followed by that of the more electro-negative, in which the termination ide has been substituted for tbe terminations ine. on, ogen, ygm, orus, turn, and ur. For example the compound of potassium and chlorine is called potassium chloride, that of potassium and oxygen, potassium oxide, that of potassium and phosphorus, potassium phosphide. 

The names of the oxysalts are derived from those of the acids by drop ping the word acid, changing the termination of the other word from cm into th , or from tc into afe, and prefixing the name of the electro-positive element dr radical thus ... 

In this class are included the more strongly electro-positive metals... 

The hydrates of the electro-negative elements and radicals are acids most of tuoee of the electro-positive elements and radicals are basic hydrales,... 

In general terms, therefor, Uie atomicity of an organic acid may be greater tb its basicity, the former representing the number of H atoms contained in its molecde, which are capable of being displaced by alcoholic radicalsi, while the latter represents tbe number of H atoms replaceable by electro-positive elements or radicals, with formation of salts or of ethers. 

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