Question

what bonding produces substances that are hard, or difficult to crush?

Answer 1

ionic,hydrogen,covalent, or metalic

Answer 2

metallic most probably

Answer 3

no, covalent networks are the strongest bond types. i.g Diamonds and granite are both made from covalent networks

Answer 4

Covalent bonds are the strongest

Answer 5

Ionic, generally, because the bare Coulombic forces are extremely strong and because the "bonding" -- I put the word in quote because I don't really approve of the concept of an ionic "bond" but that is the language used -- extends throughout the sample. That is, a Na+ cation at one end of a salt crystal is usually connected by a continuous band of strong Coulombic attractions to Cl- anions at the other end of the crystal, even if this is trillions of atoms away.

Covalent bonding CAN produce substances with very high crushing strength, when the covalent bonding extends throughout the sample. This happens in extended-network solids, such as diamond or silica. Both of these substances have very high crushing strength.

However, as a rule covalent forces tend to form molecules, which are NOT bonded to each other in the solid state, so that a sample sticks together only because of the much weaker intermolecular forces such as dipole-dipole, H-bonding, or London. Since these are much weaker forces, the solid will usually have very low crushing strength, and easily be broken apart into its component molecules. Examples are dry ice, ice, solid methanol, et cetera. Indeed, the fact that most molecular compounds have low melting points tells you that their bulk modulus (crushing strength) is low.

Metallic bonding is macroscopic, like ionic bonding, meaning the bonding extends throughout the solid, unlike covalent bonding. And metals are indeed strong, with very high resistance to crushing. So this may be an additional answer to your question. However, metallic bonding is also very flexible, meaning it does not strongly resist deformation and bending. Consequently metals, while they have very high crushing resistance, also tend to be ductile and malleable, meaning if you squeeze them they will flatten or stretch pretty easily. I am not sure if your question is sufficiently precisely phrased to distinguish between the crushing resistance of metals (which is high) and the squeezing resistance (which is not high). Ionic solids definitely have very high crushing and squeezing resistance.