Shielding r2R2 2P 2s 1s r2R2 probability of finding an electron on the sphere of radius r r But a 2s electron penetrates the 1s orbital better than a 2p electron IV-9Shielding But a 2s electron penetrates the 1s orbital better than a 2p electron r2R2 r2R2 = probability of finding an electron on the sphere of radius r 1s 2p 2s r IV-9