, family B; what properties would it have?

3. Sulphur and oxygen both belong in Group VI, although in different
families; in what respects are the two similar?

CHAPTER XVI

THE CHLORINE FAMILY

==================================================================
| | | |
| ATOMIC | MELTING | BOILING | COLOR AND STATE
| WEIGHT | POINT | POINT |
______________|________|_________|_________|______________________
| | | |
Fluorine (F) | 19.00 | -223 deg. | -187 deg. | Pale yellowish gas.
Chlorine (Cl) | 35.45 | -102 deg. | -33.6 deg. | Greenish-yellow gas.
Bromine (Br) | 79.96 | -7 deg. | 59 deg. | Red liquid.
Iodine (I) | 126.97 | 107 deg. | 175 deg. | Purplish-black solid.
==================================================================

~The family.~ The four elements named in the above table form a strongly
marked family of elements and illustrate very clearly the way in which
the members of a family in a periodic group resemble each other, as well
as the character of the differences which we may expect to find between
the individual members.

1. _Occurrence._ These elements do not occur in nature in the free
state. The compounds of the last three elements of the family are found
extensively in sea water, and on this account the name _halogens_,
signifying "producers of sea salt," is sometimes applied to the family.

2. _Properties._ As will be seen by reference to the table, the melting
points and boiling points of the elements of the family increase with
their atomic weights. A somewhat similar gradation is noted in their
color and state. One atom of each of the elements combines with one atom
of hydrogen to form acids, which are gases very soluble in water. The
affinity of the elements for hydrogen is in the inverse order of their
atomic weights, fluorine having the strongest affinity and iodine the
weakest. Only chlorine and iodine form oxides, and those of the former
element are very unstable. The elements of the group are univalent in
their compounds with hydrogen and the metals.

FLUORINE

~Occurrence.~ The element fluorine occurs in nature most abundantly as the
mineral fluorspar (CaF_{2}), as cryolite (Na_{3}AlF_{6}), and in the
complex mineral apatite (3 Ca_{3}(PO_{4})_{2}.CaF_{2}).

~Preparation.~ All attempts to isolate the element resulted in failure
u