Block (periodic table) reactivity decreases as the atomic number increases. When a halogen combines with another element, the resulting compound is called a halide. One of the best examples of a halide is sodium chloride (NaCl). The d-block is on the middle of the periodic table and includes elements from columns 3 through 12. These elements are also known as the transition metals because they show a transitivity in their properties i.e. they show a trend in their properties in simple incomplete d orbitals. Transition basically means d orbital lies between s and p orbitals and shows a transition from properties of s
Periodic table accurately predict the properties of missing elements. Following the discovery, in 1911, by Ernest Rutherford of the atomic nucleus, it was proposed that the integer count of the nuclear charge is identical to the sequential place of each element in the periodic table. In 1913, Henry Moseley using X-ray spectroscopy confirmed this proposal experimentally. Moseley determined the value of the nuclear charge of each element, and showed that Mendeleev's ordering actually places the elements in sequential order by nuclear charge. Nuclear charge is identical to proton count, and determines the value of the atomic number (Z) of each element. Using