Element Bromine, Br, Halogene. The vapour of bromine is very heavy. If a small bulb filled with bromine be broken, or if, by means of a pipette, a drop of bromine be placed at the bottom of a large, empty bottle, it is seen that the brown-yellow vapour produced remains at the bottom and sways heavily when the bottle is moved. Only after standing undisturbed for a considerable time does the bromine.

Element Krypton, Kr, Noble Gas. From Greek κρυπτον, krypton. Abundance in air is about 1. Of air contains 1 sm.

Element Polonium, Po, Metalloid. 7 natural metalloid polonium isotopes. With mass numbers 210-212, 214-216 and 218 are found as members of radioactive decay series of uranium, actinouranium and thorium. Is a rare element; its crustal abundance is 2x10. Is a soft metal with silver luster, density 9. Outer electron shell configuration is 6 s. As well as hydroxide PoO.

Element Selenium, Se, Non Metal. Whereas the amorphous selenium does not conduct the electric current to a measurable extent, the property of conductivity is possessed by the crystalline form. Hydrogen selenide is the hydrogen acid of selenium in the same sense as hydrogen sulphide is the hydrogen acid of sulphur; its aqueous solution contains the ions Se. By heating selenium with iron filings, and to treat this with hydrochloric acid. In a manner perfectly analogous to the prep.

Element Tellurium, Te, Metalloid. While iodine is very similar to bromine, if not in external appearance, at least in the nature of the corresponding compounds, the differences between selenium and tellurium are more pronounced, so that it has repeatedly been regarded as doubtful whether these two elements ought to be regarded as members of the same family. The combining weight of tellurium, Te. Combines with the metals to form tellurides; these correspond to the sulphides.

From a Greek word meaning strange one or stranger; it was a stranger indeed in krypton fraction. Abundance in atmosphere is 0. By volume; deposits are estimated as 1.