The Hill system (or Hill notation) is a system of writing empirical chemical formulas, molecular chemical formulas and components of a condensed formula such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then the number of all other chemical elements subsequently, in alphabetical order of the chemical symbols.
Iodine clock reaction. The iodine clock reaction (STd3) is a classical chemical clock demonstration experiment to display chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. Two colourless solutions are mixed and at first there is no visible reaction.
Ernest Z. Potassium iodide is an ionic compound. Potassium is in Group 1 of the Periodic Table. That means it is a metal. Iodine is in Group 17 of the Periodic Table. That means it is a nonmetal. Metals react with nonmetals to form ionic compounds. A sodium atom transfers an electron to a chlorine atom to form a sodium ion and a chloride ion. The product is the ionic compound, sodium chloride. In the same way, a potassium atom transfers an electron to an iodine atom to form a potassium ion and an iodide ion. So, potassium iodide is an ionic compound.