50 PRESIDENTIAL ADDRESS SECTION B. 



hydride is a salt-like non-metallic material made from lithium metal 

 and hydrogen gas, both of which are electrically neutral (not posi- 

 tive) : we must therefore assume the equation Li v + H+' = 

 (Li ' J H+) in which the arrangement of the electrons is the same 

 as in hydrogen gas. It is stated, however, that when LiH is 

 melted and electrolysed, lithium metal appears at the kathode and 

 hydrogen gas at the anode.* Now the kathode is negative, hence 

 the appearance of lithium metal (Li ' ; ) is normal, but at the anode 

 we must assume that (H+)" forms a negative ion attracted 

 there, and that it then loses an electron to the positive 

 anode, giving H +/ which is nascent hydrogen. We are thus again 

 led to the assumption that hydrogen gas consists of the positive 

 (H+) joined to the negative (H+)". The only possible reconcilia- 

 tion of all the facts is to assume that (H+)" has not got its electrons 



at a distance 7 



close together. Thus hydrogen gas is (H+ H + )- 



/ 



(See Fig. 2.) Some writers get over the difficulty by 

 dissecting the electron itself into a repulsive electric part 

 and an attractive magnetic part, but this is at present 

 scarcely credible. Similarly in methane and other inactive 

 hydrogen compounds one has to assume that carbon parts 

 with 4 electrons to 4 neutral H atoms giving 4 distant (H+)' r 

 groups round the carbon kernel ; whereas on the contrary in a 

 hydrogen-compound which is a tetrabasic acid (e.g., H 4 Si 4 ) the 

 hydrogen outside consists of plain hydrions (H+) and the 8 

 electrons left over are pushed inside close to the kernel, thus 

 (H+) 2 SiO /""" (H+) 2 . 



Having now dealt full) 7 with hydrogen in its different 

 phases let us now consider what is the nature of another 

 simple monovalent element. Taking lithium as the simplest 

 case, we remember that we have arrived at the conclusion 

 that it consists of a small nucleus composed of 7 hydrions 

 held together by 4 electrons, giving a total positive nucleus charge 

 of 3. Since lithium metal is neutral, and lithium in the ionised 

 state positively monovalent, we see that the nucleus must carry two 

 negative electrons just outside it. This combination of nucleus 

 and close electrons is called the "kernel" of the atom. The 



"kernel" is the same as the "ion" when there are not many out- 

 side electrons. Thus lithium ion Li ' is 0(411 + + 40 + 3H+)0, 

 in which is the electron. It has 7 plus and 6 minus charges, 

 therefore has + 1 valency. (See Fig. 3.) Lithium metal is the 

 foregoing Li ■ with a seventh electron at a comparatively great 

 distance, viz., [0(411+40 3H+)0 0] making it electrically neutral. 

 Now the number 3 in the case of lithium, which is both the nuclear 

 charge and the total of the number of external electrons (in this 

 case 2 + 1) coincides with the fact that in the Periodic Law as 

 ordinarily written lithium is the third element in order. Similarly 

 beryllium, the fourth element in the ordinary Periodic Law, has a 



* Hydrogen appears at the katho le in the electrolys's of water, etc. 



