11. Write the equations for all the reactions involved in Marsh's test for arsenic.
12. Write the names and formulas for the acids of antimony.
13. Write the equations showing the hydrolysis of antimony trichloride; of bismuth nitrate.
14. In what respects does nitrogen resemble the members of the phosphorus family?
CHAPTER XXI
SILICON, TITANIUM, BORON
| SYMBOL | ATOMIC WEIGHT | DENSITY | CHLORIDES | OXIDES | |
| Silicon | Si | 28.4 | 2.35 | SiCl4 | SiO |
| Titanium | Ti | 48.1 | 3.5 | TiCl4 | TiO |
| Boron | B | 11.0 | 2.45 | BCl3 | B2O3 |
General. Each of the three elements, silicon, titanium, and boron, belongs to a separate periodic family, but they occur near together in the periodic grouping and are very similar in both physical and chemical properties. Since the other elements in their families are either so rare that they cannot be studied in detail, or are best understood in connection with other elements, it is convenient to consider these three together at this point.