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fig. 200. tartaric acid

TARTARIC ACID COOH. CHOH. CHOH. COOH

In Tartaric acid we have a symmetrical molecule, the two halves being similar. Fig. 200. The two Carbon atoms are joined by using two funnels from each Carbon. The two Hydroxyl (OH) groups place themselves over two funnels as usual, the Oxygen being drawn down into the funnels as in Methyl Alcohol. The well-known Carboxyl group. COOH, is shown here in the form in which it appears in other acids. It will be seen that the four central Anu of the Carbon make a grand centre for the group, and the eight funnels of the Carbon atom place themselves at the ends of the Oxygen atoms. The triplets of the Hydrogen atom come between the two Oxygen atoms and push them apart. These two triplets are over the two funnels of a central Carbon atom. The remaining four triplets of the Hydrogen atom float over the funnels of the Carbon atoms which are attached to the Oxygen, but the description is not clear as to the exact distribution of these four triplets.

MALEIC ACID COOH. CH - CH. COOH

fig. 201. maleic acid

This compound has a double bond in the centre, which means that four of the funnels of each central Carbon are engaged in making this bond. Fig. 201. The octahedrons may be visualized as standing parallel with one complete side used in these bonds. The remaining valencies point to two corners of a tetrahedron. One pair of funnels in each central Carbon is used in holding a Hydrogen atom, this Hydrogen dividing into its two triangles as usual. The other pair of funnels, completing the four valencies, is used to hold a Carboxyl group. This Carboxyl group is arranged just as is the Carboxyl group in Tartaric acid. It is shown making an angle with the Hydrogen to indicate that the whole is in three dimensions and that the valencies point to the corners of a tetrahedron.

di-ethyl ether <c,hs)30

di-ethyl ether <c,hs)30

fig. 202. di-ethyl ether

In the Ethers a group of the ethyl type is attached to another by means of an Oxygen atom. The example given here is Di-ethyl ether, but the other Ethers are on the same plan.

In Fig. 202 the molecule is shown lying on its side like a fallen column, the two groups of C,H, being linked by the Oxygen atom. In the case where two Carbon atoms are joined together four funnels take part, the negative funnel of one Carbon being linked by lines of force to the positive of another.

In the Ethers the tail ends of the double Oxygen snake open out and point to a negative and a positive funnel respectively. The Oxygen atom is thicker and shorter than usual, and the two parts of the molecule hold together because the snakes are pulled in opposite ways because one is negative and the other positive. Four funnels of Carbon are occupied by the Oxygen.

In their natural free state there is a normal position for the atom and its parts. The Carbon atom, for instance, naturally points up and down as in an octahedron. Here the Oxygen pulls the Carbon atoms askew so that they are leaning a little forward. If it were not held strongly the molecule would fall apart.

In the diagram an attempt has been made to show the octahedron as if we were looking direct at one face. Four funnels are shown and the other four indicated.

The Hydrogen atoms break up into half-Hydrogens, as in Methane, and float over the funnels not occupied by the Oxygen, or are used to link the Carbons together.

BENZENE C.H.

Benzene is the first member of the closed chain, or ring, series. It consists of six Carbon and six Hydrogen atoms and can be represented diagrammatically as a single ring. Fig. 203.

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