Assertion: selenium's number | /r/HasProperty | 684.9°c
Facets:
Source sentences:
text: Atomic number 34; atomic weight 78.96; melting point 217°C; boiling point 684.9°C; specific gravity (gray) 4.79; (red) 4.5; (black) 4.28; valence 2, 4, or 6.