An element have atomic weight 40 and its electronic configuration is 1 s2 2 s2 2 p6 3 s2 3 p6. Then its atomic number and number of neutrons will be:

Question

An element have atomic weight 40 and its electronic configuration is 1 s2 2 s2 2 p6 3 s2 3 p6. Then its atomic number and number of neutrons will be: (A) 18 and 22 (B) 22 and 18 (C) 20 and 20 (D) 40 and 18

Tardigrade Admin · Accepted Answer

Given, electronic configuration =1 s2, 2 s2 2 p6, 3 s2 3 p6 and atomic weight =40 Hence, atomic number =2+2+6+2+6 =18 Number of neutrons = atomic weight - atomic number =40-18=22

Q. An element have atomic weight $40$ and its electronic configuration is $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6}$ . Then its atomic number and number of neutrons will be:

18 and 22

22 and 18

20 and 20

40 and 18

Given, electronic configuration $= 1 s^{2}, 2 s^{2} 2 p^{6}, 3 s^{2} 3 p^{6}$
and atomic weight $= 40$
Hence, atomic number $= 2 + 2 + 6 + 2 + 6$
$= 18$
Number of neutrons
$=$ atomic weight $-$ atomic number
$= 40 - 18 = 22$

Q. An element have atomic weight 40 and its electronic configuration is 1s22s22p63s23p6. Then its atomic number and number of neutrons will be: