Metacognition is  cognition about cognition, thinking about thinking, or knowing about knowing. It comes from the root word  meta , meaning beyond. It can take many forms; it includes knowledge about when and how to use particular strategies for learning or for problem solving. There are generally two components of metacognition: knowledge about cognition, and regulation of cognition.
In chemistry, an ionic compound is a chemical compound in which ions are held together in a structure by electrostatic forces termed ionic bonds.The positively charged ions are called cations and the negatively charged ions are called anions.onic compounds without the acidic hydrogen ion (H +), or the basic ions hydroxide (OH â) or oxide (O 2â), are also known as salts and can be formed by acid-base reactions. Ionic compounds containing hydrogen ions are classified as acids and compounds containing hydroxide or oxide ions are classified as bases.
1 Most crystals are ionic compounds. 2  This is because the ions in these compounds tend to stack into crystal lattices to balance between the attractive forces between opposite ions and the repulsive forces between like ions. 3  Covalent or molecular compounds can exist as crystals, though. Ionic compounds tend to have higher melting and boiling points than covalent compounds. 2  Ionic compounds tend to be hard and brittle while covalent compounds tend to be softer and more flexible. 3  Ionic compounds conduct electricity when dissolved in water while covalent compounds typically don't.