Explore how a kaleidoscope works. find two mirrors, and hold them upright on the desk, so they are at an angle to each other like an open book. set an object between them, and look in the mirrors. how many images do you see? slowly bring the mirrors together. what happens? are the images you see the same? can you explain what you see?

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)