subshell # orbitals max # electrons shape of a single orbital shape of all orbitals s 1 2 ospherical spherical p 3 6 ¥dumbbell semi-spherical d 5 10 ✜double dumbbell “spherical” f 7 14 ★triple dumbbell “spherical” g 9 18 quadruple dumbbell “spherical” h 11 22 pentuple dumbbell “spherical” i 13 26 hextuple dumbbell “spherical” etcetera Below is a summary showing the shells, how we designate the subshells and the number of electrons in them, and how the maximum number of electrons is related. Notice that the sum of the maximum number of electrons in each subshell adds up to the maximum number of electrons allowed in a shell. The unused subshells are in green.
Chapter 8 Electron Configuration and Chemical Reactivity 5shell subshells with maximum electrons maximum electrons in a shell, 2n21 1s22(1)2= 2 2 2s22p62(2)2= 8 3 3s23p63d102(3)2= 18 4 4s24p64d104f142(4)2 = 32 5 5s25p65d105f145g182(5)2= 50 6 6s26p66d106f146g186h222(6)2= 72 7 7s27p67d107f147g187h227i262(7)2= 98 The 7 shells in use are the periods numbered on the periodic table below. The 4 subshells in use are shown as blocks on the periodic table. The superscripts indicate the maximum number of electrons allowed in each subshell, the symbols approximate orbital shapes: 1 1s11s22 2s12p1 3 4 s2o3d1d10✜p6¥5 6 7 4 4f1f14★5 The Aufbau Principle and Orbital Overlapping The Aufbau Principle gives the energy order of the subshells as they are found on the periodic table. Electrons are “placed” into the lower energy subshells first. The lower energy refers to the “place” closest to the nucleus. The following mathematical array can be constructed from the shell number and the allowed number of subshells: subshell 1s s 2s 2p h 3s 3p 3d e 4s 4p 4d 4f l 5s 5p 5d 5f 5gl 6s 6p 6d 6f 6g 6h7s 7p7d 7f 7g 7h 7i the subshells in green italics are not needed8s The Aufbau Principle is followed when we use the order given by the diagonal arrows. Thus, the theoretical order for filling all subshells in all atoms is as follows: subshells1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p done energy increases ®orbitals oo3¥o3¥o5✜3¥o5✜3¥o7★5✜3¥o7★5✜3¥
Chapter 8 Electron Configuration and Chemical Reactivity 6•To get the electron configuration, count the electrons, place them into subshells in the Aufbau order.We will ALWAYS use the Aufbau Principle in this course. This is the same order for filling as we see in the periodic table, even though the periodic table was designed using Periodic Law that was based upon observations and not theory. The periodic table was designed so that elements with similar bonding patterns are found in the same group. This was a pragmatic approach. All of the theories we are learning were developed to explain this phenomenon. The green highlighting shows the position of all 4 subshells in shell number 4 on the periodic table.