What is the estimated effective nuclear charge, z eff, experienced by an electron in a 3p orbital of a chlorine atom? a. -1 b. 5 c. 7 d. 17,

Effective nuclear charge is the charge felt by valence electrons of multi-electron atom taking into consideration the number of shielding electrons that surround the nucleus.
To calculate Z eff for electron we use this formula :
Z eff = Z - S where Z is the number of protons in nucleus and S is the average amount of electron density between the nucleus and electron in consideration
so Z eff = 17 - 10 (core electrons) = 7 
So the correct answer is C 

Hello thereone of the following properties was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version. which property fits this description? answer: atomic mass  was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

Are there any options that could alot..