Question

The atomic number of an element is 20. In which period of the modern periodic
table, could this element be placed? Why? How will you decide whether the
element is a metal or a non-metal?​

Answer 1

Answer

4 th period,s block and metal

Explanation:

according to aufbau principle the general electronic configuration of 20 is 1s,2s,2p,3s,3p,4s

where s carries 2 electron,p carries 6 electron

as last shell that is 4s carries 2electron the element is metal because an element to be metal the outer shell must have electrons between 1-4