Write the atomic number of the element in the third period and group 17 of the period table.

Number of elements in the third period?

Name the elements included in the first period of the periodic table.

The representation of Bohr model of elements with atomic number 3 to 9 in the second period of the periodic table. Is there are in the number of shells with the increase in atomic number?

The outermost electronic configuration of A is 2s^2 2p^2 (Symbols are not real) a) Find the group number, block of this element. b) Write the chemical formula of the compound obtained by the reaction of A and chlorine. c) Write down the complete subshell electronic configuration of the element coming just below A in the same group of the periodic table?

The physical and chemical properties of elements are periodic functions of their atomic numbers. a) The atomic number of an element 'X' is 19. Write the group number, period and block to which 'X' belong in the periodic table. b) Name the element with i) highest electronegativity and ii) highest electron gain enthalpy