�ݺ�ߣ

This document discusses crystals and provides examples of different types of crystal compounds, including sodium chloride, copper(II) sulphate, potassium chromate(VI), and potassium dichromate. It notes that crystals have fixed geometrical shapes like cuboids and prisms, with flat surfaces and sharp angles, and that the angles between neighboring surfaces are always the same for a given substance, even if the crystals are different sizes.Read less