Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| element | group | period | reaction | potential |
| --- | --- | --- | --- | --- |
| Gold | 11.0 | 6.0 | Au 3+ + 3e − → Au | 1.56 V |
| Platinum | 10.0 | 6.0 | Pt 2+ + 2e − → Pt | 1.18 V |
| Iridium | 9.0 | 6.0 | Ir 3+ + 3e − → Ir | 1.156 V |
| Palladium | 10.0 | 5.0 | Pd 2+ + 2e − → Pd | 0.987 V |
| Osmium | 8.0 | 6.0 | OsO 4 + 8 H + + 8e − → Os + 4 H 2 O | 0.838 V |
| Silver | 11.0 | 5.0 | Ag + + e − → Ag | 0.7996 V |
| Mercury | 12.0 | 6.0 | Hg 2+ 2 + 2e − → 2 Hg | 0.7973 V |
| Polonium | 16.0 | 6.0 | Po 2+ + 2e − → Po | 0.65 V |
| Rhodium | 9.0 | 5.0 | Rh 2+ + 2e − → Rh | 0.600 V |
| Ruthenium | 8.0 | 5.0 | Ru 2+ + 2e − → Ru | 0.455 V |
| Copper | 11.0 | 4.0 | Cu 2+ + 2e − → Cu | 0.337 V |
| Bismuth | 15.0 | 6.0 | Bi 3+ + 3e − → Bi | 0.308 V |
| Technetium | 7.0 | 5.0 | TcO 2 + 4 H + + 4e − → Tc + 2 H 2 O | 0.272 V |
| Rhenium | 7.0 | 6.0 | ReO 2 + 4 H + + 4e − → Re + 2 H 2 O | 0.259 V |
| Antimony | 15.0 | 5.0 | Sb 2 O 3 + 6 H + + 6e − → 2 Sb + 3 H 2 O | 0.152 V |
Question:
Which lowest period's element is ruthenium?
Answer:
5.0