Answer: all elements in the periodic table is classified as elements
Explanation:
The structure of the table shows periodic trends. The seven rows of the table, called periods, generally have metals on the left and nonmetals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases
D & e represent the same element
What compound are you trying to show
Atomic number = 20 -------> Ca (calcium)
Calcium has four shells (1, 2, 3, 4) and two sublevels ( s, p ).
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
