Why do the atomic radii of the elements decrease across Period 3 from sodium to chlorine?

The atomic radius of an atom is the distance from the atom's nucleus to its outermost electron. Moving across Period 3, the number of protons in the nucleus increases - for example sodium has 11 protons, and chlorine has 17 protons. Nuclear charge increases across the period, therefore the attraction between the positively charged nucleus and negatively charged electrons increases, so the atomic radii decreases. The number of electrons also increases across a period, but as each extra electron enters the same principal energy level, there is relatively little extra shielding.

AT
Answered by Amy T. Chemistry tutor

28326 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Calculate the pH of a 0.0131 mol dm^-3 solution of calcium hydroxide at 10 degrees centigrade.


Calculate the pH of 0.1M Benzoic Acid (C6H5COOH). Ka = 6.3x10-5 M


What is an oxidising agent?


Explain why fluorine is more reactive than chlorine.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences