Chemistry - Do the names of some elements have anything to do with planets?

Solution 1:

Neptunium (93) and plutonium (94) were so named because they followed uranium (92) on the periodic table.

Uranium was named after Uranus. German chemist Martin Heinrich Klaproth discovered uranium in 1789, eight years after William Herschel discovered Uranus. At the time, uranium was the densest element known and Uranus was the farthest planet from the sun known.

Solution 2:

Asked and answered, but this is a good place to include other astronomically named elements:

• cerium named after the asteroid Ceres (or the Roman goddess of agriculture)
• helium from the Greek helios or "Sun"
• mercury OK, named after the Roman god, but so was the planet
• palladium named after the asteroid Pallas, discovered the year that Pd was first isolated
• selenium from the Greek "selene" for "Moon"
• tellurium from the Greek "tellus" for "Earth"
• krypton Sorry comic fans, the name predates Superman

Naming information is from here and a very nice element etymology website. Now that you know something, you should probably take a mentally stimulating diversion.