Chemical element of metals. Cu comes from Cuprum, Fe comes from Ferrum, Ag from Argentum. The symbols were not followed by a period (full stop) as with abbreviations. Later chemical elements were also assigned unique chemical symbols, based on the name of the element, but not necessarily in English. For example, sodium has the chemical symbol 'Na' after the Latin "natrium". The same applies to "W" (wolfram) for tungsten, "Fe" (ferrum) for iron, "Hg" (hydrargyrum) for mercury, "Sn" (stannum) for tin, "K" (kalium) for potassium, "Au" (aurum) for gold, "Ag" (argentum) for silver, "Pb" (plumbum) for lead, "Cu" (cuprum) for copper, and
Au pair other adult caregiver is also home and fully responsible for the infant. The Au Pair Program is administered by the US Department of State. Participating families and au pairs must work with one of the currently 12 approved agencies. Au pairs enter the United States on a J-1 visa. According to the Internal Revenue Service, an au pair will almost always be a nonresident alien, and will be required to file a tax return on Form 1040NR or Form 1040NR-EZ to report his or her au pair wages. These wages, however, are not usually subject to social security and Medicare