Dec 16, 2025 · Chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements. All the matter in the universe is composed of the …

Dec 30, 2025 · What are some important uses of gold today? What are the physical and chemical properties that make gold unique as an element?

Dec 22, 2025 · The processes that deliver dissolved, particulate, and gaseous materials to the oceans ensure that they contain, at some concentration, very nearly every element that is …

Jan 2, 2026 · Oxygen forms compounds by reaction with practically any other element, as well as by reactions that displace elements from their combinations with each other; in many cases, …

Dec 6, 2025 · Nitrogen, nonmetallic element of Group 15 [Va] of the periodic table. It is a colorless, odorless, tasteless gas that is the most plentiful element in Earth’s atmosphere and …

Dec 3, 2025 · Aluminum, chemical element, a lightweight silvery white metal of Group 13 of the periodic table. Aluminum is the most abundant metallic element in Earth’s crust and the most …

Nov 29, 2025 · Elements can combine with one another to form a wide variety of more complex substances called compounds. The number of possible compounds is almost infinite; perhaps …

Dec 11, 2025 · magnesium (Mg), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table, and the lightest structural metal. Its compounds are widely used in …

Jan 2, 2026 · Compounds of iron in the +2 state are designated ferrous and contain the pale green Fe 2+ ion or complex ions. Compounds of iron in the +3 state are called ferric and …

In the formulas of ionic compounds, simple ions are represented by the chemical symbol for the element: Cl means Cl −, Na means Na +, and so on. When individual ions are shown, …