Using the Periodic Table above that means any compound that contains an element shown in orange will contain ionic (electrovalent) bonds. Compounds that form between two non-metals (or between non-metals and metalloids) will contain covalent bonds. Using the Periodic Table above that means any compound that contains element shown in yellow or green will contain covalent bonds.
Porpoises are a group of fully aquatic marine mammals, that are sometimes referred to as mereswine, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). There are 8 extant species of porpoise.
Porpoises are part of the scientific family Phocoenidae, while dolphins are part of the Delphinidae family. When you concentrate on the differences at the family level, dolphins and porpoises can seem quite different. There are definite, yet subtle physical differences between the two aquatic mammals. Porpoises tend to be smaller than dolphins. While dolphins can be 10 feet long (or longer!), porpoises are rarely longer than 7 feet.