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 country. The Council of Europe recommends that au pairs be issued standard contracts with their family. Some au pairs are now male, but females remain the overwhelming majority. Many governments impose limits as to how many hours an au pair is allowed to work. Tasks can include taking children to and from school, taking children to after-school activities, cooking, cleaning, ironing, tidying up and babysitting. Each placement varies depending on the host family. In many developing countries, an abundant supply of local domestic labour is still available, so there is little or no demand for au pairs. Au pair relationships