The network covalent atomic solid has high melting points because it is held together by bonds.
Section 13.6 contains examples of this class of solids.
Gold is an atomic solid because it is a metal.
There is a compound called Ethanol.
A solid is a molecule.
CaF2 is an ionic compound.
The unit cells that we examined in Section 13.3 are closely related to the structures of many ionic solids.
Because ionic compounds contain both cations and anions, their structures must accommodate two different types of ion.
The cations and anions attract each other.
The number of close cation-anion interactions is represented by the coordination number.
The crystal structure of a particular Cesium chloride compound is the structure that maximizes the coordination number while accommodating both charge neutrality and different sizes of cations and anions.
The formula for the compound indicates that the ratio of Cs to Cl of1:1 is represented by the colored chloride unit cell.
The structure of calcium sulfide is the same as that of cesium chloride.
An example of an ionic compound with different ion sizes is sodium chloride.
The disproportionate sizes must be accommodated by the crystal structure.
If ion size was the only consideration, the larger chloride anion could theoretically fit many of the smaller sodium cations around it.
The coordination number is limited by the number of chloride anions that can fit around the small sodium cation.
Each unit cell contains four chloride anions and four sodium cations, resulting in a ratio of1:1, as the formula of the compound specifies.
Other compounds have the same structure as the sodium chloride.
A coordination number of even 6 is physically impossible with the different colored compound.
The crystal structure shown in different ion in the compound is represented by the spheres in this figure.
The zinc blende (ZnS) figure shows an empty space in the center of a four atom arrangement.
Each unit cell contains four sulfide anions and four zinc cations, and each of the four zinc cations is completely contained within the unit cell.
The zinc blende structure is found in other com S2 pounds.
The calcium cations occupy the lattice sites of a face-centered compound.