Short answers, pulled from the story.
A chloride ion measures 181 picometers in diameter while a neutral chlorine atom measures only 99 picometers. This size difference exists because the anion holds one extra electron compared to its atomic form.
Seawater contains 19400 milligrams per liter of chloride ions. Smaller quantities exist within inland seas like the Dead Sea in Israel and subterranean brine wells near Utah's Great Salt Lake.
Kidneys regulate serum chloride levels by filtering and reabsorbing ions along the nephron. Mammalian blood plasma maintains a concentration of 100 millimolar through this process.
The chlor-alkali industry converts concentrated sodium chloride solutions into chlorine gas and sodium hydroxide using membrane cells. Chloride ions lose electrons to become chlorine gas at the anode while water molecules gain electrons at the cathode to produce hydrogen gas and hydroxide ions.
Aquatic environments suffer when increased concentrations alter stream acidity levels and cause mortality rates to rise among plants and animals. Natural lake mixing patterns become disrupted by dense saline layers and microbial species composition shifts even at relatively low salt concentrations.