-Calcium (Ca), gold (Au), and hydrogen (H) are chemical elements that are examples of basic chemical substances: they cannot be broken down into simpler forms.
– The periodic table gives information about all of the 116 known elements arranged in order of their atomic number: the number of protons in each element’s atomic nucleus.
-Elements 110 through 116 have been produced artificially.
-It was devised in 1869 by the Russian chemist Dmitri Mendeleyev (1834 1907). The table groups elements into seven horizontal lines or periods. As we read from left to right the elements become less metallic. The elements in each vertical group have similar chemical properties.