Describe patterns or relationships observed in the atomic structure and the arrangement of elements 1-18 on the Periodic Table.

Which is true of chemicals? a. things containing chemicals always cost a lot of money. b. chemicals are never dangerous. c. chemicals are in many substances in a home. d. chemicals are rarely found on earth.

Write the empirical chemical formula of calcium with a mass percent of 38.8, phosphorus with a mass percent of 20.0, and oxygen with a mass percent of 41.3.

If a polyatomic ionic compound has gained two hydrogen ions, then how does its name begin?