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
Tangible symbol systems of communication for individuals who are unable to understand or communicate using abstract systems, such as speech or sign language. Properties of tangible symbols include permanency, capacity to be manipulated by both the user and the communication partner, and an obvious relationship between the symbol and the referent. They can represent items, people, activities and/or events, and look or feel similar to what they refer to. For example, a cup can be used as three-dimensional tangible symbol to represent the action: "drink". A photograph of a cup can be used as a two-dimensional tangible symbol to also represent the action