Gold is very special metal. Its chemical symbol is Au with atomic number 79. It is a dense, Yellow, precious, Ductile and Malleable metal used ( as chlonide compound ) for medicinal pues also in the treatment of rheumatoid arthritis. Pure gold is 24 carats. It is too malleable to be used so, it is mixed with copper ordinary jewellary are 22 carats. 24 carats is a 100 % gold and 12 carats is 50% pure. It is alloyed with silver to be used in dental cavity fillings. It has valuency 1 & 3.