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 hours of academic credit or its equivalent during their program year. The host family is required to provide (up to) the first $1,000 toward the cost of the au pair's required academic course work. The Extension Program When the Au Pair Program started in the United States in 1989, au pairs were only allowed to stay in the country and work as au pairs for a 12-month period. In 2006, the U.S. Department of State allowed au pairs to legally extend their stay and work for 6, 9, or 12 additional months. The program’s regulations state that the Department of