Part 8
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when bonds are broken what occurs?
endothermic rxn +delta H
when bonds are formed what occurs?
exothermic rxn +delta H
aggregates of positively and negatively charged ions are …?
ionic solids
what are the physical properties of ionic solids? why so?
high melting point, high boiling point, poor electrical conduction in solid phase. (due to strong electrostatic interactions)
what is a metallic solid?
consists of metal atoms packed together as closely as possible
what are the physical properties of metallic solids? why so?
high melting points, high boiling points due to strong covalent interactions
the repeating units of crystals (both ionic and metallic) are represented by what?
unit cells
what are the three cubic unit cells?
simple body-centered face-centered
how many atoms are in a body-centered cubic unit cell?
2
how many atoms are in a face-centered cubic unit cell?
4
a solid can be either …
crystalline (3d - salt) amorphous (not 3d- glass)
are most solids crystalline or amorphous?
crystalline
what are the two most common forms of crystals ? (solid structure)
metallic and ionic
vapor pressure increases as ______ increases.
vapor pressure increases as temperature increases
the temperature at which the vapor pressure of the liquid equals the external pressure is called what?
boiling point
when a solid goes directly to gas the process is called what?
sublimation
what is the reverse of sublimation?
deposition : gas to solid
fusion is AKA
melting
vaporization is AKA
evaporation
delta H will be -/+ for melting, vaporization and sublimation?
positive endothermic