Final answer:
Hardness in minerals is their ability to resist being scratched, and it is measured by the Mohs' scale of mineral hardness. Mohs' scale is qualitative and uses ten reference minerals for comparison. Mineral hardness can also be related to lattice energy in ionic materials.
Step-by-step explanation:
The hardness of a mineral refers to a mineral's ability to resist being scratched. This characteristic of hardness is typically measured using the Mohs' scale of mineral hardness, which was developed by Frederich Mohs in 1822. Using this scale, minerals are ranked relative to each other based on how easily they can be scratched. The scale lists ten reference minerals of increasing hardness and is qualitative. For example, diamond, which is a 10 on the Mohs scale, is not quantitatively 10 times harder than talc, which is a 1 on the scale.
When testing mineral hardness, you might use common objects that have known hardness values as defined by the Mohs scale to scratch the surface of the mineral in question. In a classroom setting, these objects can provide an understandig of the concept of hardness without the need for specialized equipment. Additionally, factors like lattice energy can give insight into the hardness of ionic materials, which is related to how tightly ions are held together in a material. For instance, magnesium oxide (MgO) has greater hardness compared to sodium fluoride (NaF) due to its higher lattice energy.