Crystals break down into four primary types: ionic, molecular, metallic and covalent. These categories divide crystals into groups with other crystals bearing similar physical and chemical properties. Factors determining the specific variety of crystals include the size and shape of surrounding lattice, particles on certain points in the lattice and attractions or bonds existing between crystal particles.
The physical and chemical properties of crystals vary widely, although crystals classifying as the same type share many common characteristics. Ionic crystals feature a hard composition and withstand high melting temperatures. They consist of compounds with two individual atoms fusing together. Melting ionic crystals creates a thick liquid that conducts electricity.
Ionic crystals exhibit strong pulls among unlike particles, bringing positively and negatively charged ions together. Like particles sharing close quarters, however, these form a strong repulsion to each other. This characteristic makes ionic crystals relatively brittle and fragile; they break and shatter easily under stress as they lack the sufficient strength to keep unlike particles together.
Molecular crystals have a softer physical composition than ionic crystals. They have lower melting points and bend easily, thanks to weak particle connections. Some molecular crystals form from individual atoms, while others are derived from polar or non-polar molecules.
Covalent crystals exhibit a large lattice network. They are durable and strong and are the largest crystals out of the four primary types. Metallic crystals conduct heat and electricity, and they bear a characteristic shine.