# Pekka Pyykkö

Veli Pekka Pyykkö (born 12 October 1941) is a Finnish academic. He was professor of Chemistry at the University of Helsinki. From 2009–2012, he was the chairman of the International Academy of Quantum Molecular Science. He is known for his extension to the periodic table of elements, known as the Pyykkö model.
Pyykkö has also studied the relativistic effects present in heavy atoms and their effects in NMR.

## Pyykkö model

After the 118 elements now known, Pekka Pyykkö predicts that the orbital shells will fill up in this order:
* 8s,
* 5g,
* the first two spaces of 8p,
* 6f,
* 7d,
* 9s,
* the first two spaces of 9p,
* the rest of 8p.
He also suggests that period 8 be split into three parts:
* 8a, containing 8s,
* 8b, containing the first two elements of 8p,
* 8c, containing 7d and the rest of 8p.
Pyykkö model :
| | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface | Pyykkö-displaced elements are in boldface |
| 8 | 119 Uue | 120 Ubn | 121 Ubu | 122 Ubb | 123 Ubt | 124 Ubq | 125 Ubp | 126 Ubh | 127 Ubs | 128 Ubo | 129 Ube | 130 Utn | 131 Utu | 132 Utb | 133 Utt | 134 Utq | 135 Utp | 136 Uth | 137 Uts | 138 Uto | 141 Uqu | 142 Uqb | 143 Uqt | 144 Uqq | 145 Uqp | 146 Uqh | 147 Uqs | 148 Uqo | 149 Uqe | 150 Upn | 151 Upu | 152 Upb | 153 Upt | 154 Upq | 155 Upp | 156 Uph | 157 Ups | 158 Upo | 159 Upe | 160 Uhn | 161 Uhu | 162 Uhb | 163 Uht | 164 Uhq | 139 Ute | 140 Uqn | 169 Uhe | 170 Usn | 171 Usu | 172 Usb |
| 9 | 165 Uhp | 166 Uhh | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 167 Uhs | 168 Uho |
| | s-block | s-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | g-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | f-block | d-block | d-block | d-block | d-block | d-block | d-block | d-block | d-block | d-block | d-block | p-block | p-block | p-block | p-block | p-block | p-block |
The compact version:
Pekka Pyykkö correctly predicted the existence of chemical bonds between gold and the noble gas xenon, which is usually inert; this bond is known to occur in the cationic complex tetraxenonogold(II) (AuXe$^{2+}$ $_4$). He also correctly predicted the existence of gold–carbon triple bonds.