Solids Flashcards
Covalent solids:
- Bond strength?
- Melting point?
- Hardness?
- Electrical conductivity?
- Dissolve in water?
- Examples?
Consist of atoms completely held together by covalent bonds throughout the entire crystal lattice.
- Very strong bonds
- Very high melting points
- Very hard
- Do not conduct electricity
- Do not dissolve in water
- Ex diamond (made of carbon), Silicon carbide (SiC), and aliminum nitride (AlN)
Isoelectronic atoms/ions:
Atoms or ions that have the same number of electrons
Ionic solids:
- Bond strength?
- Melting point?
- Hardness?
- Electrical conductivity?
- Dissolve in water?
- Examples?
Made up of ions held together by ionic bonds.
- Strong electrostatic attrctions
- High melting points
- Relatively hard
- Solid form doesn’t conduct electricity, but molten (liquid) form does
- Dissolve easily in water
- Ex NaCl and KCl
Sublimation:
When a solid turns directly into a gas, instead of turning into a liquid first.
Polymorphic:
Substances that can assume more than one crystalline form. (ex Sulfur)
X-ray diffraction:
Used to to measure the diameter (or radius) or atoms within a crystal. X-ray wavelengths are are similar to the diameter of the atoms, and thus they get diffracted.
Allotropes:
The name of the different crystalline forms of a polymorphic element. Ex graphite and diamond are allotropes of carbon.
Crystalline Solid:
A solid that exists in a definite 3D geometrical shape. They have sharp metling points due to the fact that the chemical bonds between the atoms, ions, and molecules are all the same.
Amorphous:
A solid that does not have a definite crystalline shape. Ex Glass.
Heat of fusion:
- Units?
The energy required for a solid to turn into a liquid while remaining at the melting point.
- Can be expressed in calories per gram or calories per mole
Glasses:
- Melting point?
- Chemical bond strength?
A category of solid substances that appear to be crystalline, but are not. Their atoms, ion, or molecules are amorphous and thus if they were broken would break randomly.
- relatively large melting point ranges, asthey become soft over several degrees of increasing temperature before finally becoming a liquid
- the chemical bond strengths vary throughout the solid
Metallic solids:
- Bond structure?
- Melting points?
- Hardness?
- Electrical conductivity?
- Dissolve in water?
- Other charactersitics?
- Examples?
Held together by a metallic bond in which positive ions are floating in a “sea” of electrons which they all donated.
- Each atom is surrounds by 8 other atoms as its nearest neighbors in a cubic closest-packed structure, OR 12 other atoms in a **hexagonal **closest-packed structure.
- Vary over wide ranges
- vary over wide ranges
- Excelent conductors of electricity and heat because of the mobility of the electrons
- Do no dissolve in water
- Malleable (can be rolled or beaten into fine sheets), Ductile (can be drawn into fine wires), and luster (shine) in both solid and liquid states
- Iron (Fe), copper (Cu), and silver (Ag)
Crystal lattice:
The arrangement of atoms within a crystal.
Specific Heat:
- Formula?
Calories required to raise the temperature of 1 gram of a substance by 10 Celsius.
Atomic weight= 6.2/specific heat
Angstrom unit:
used to measure the radii radius of atoms and ions.
1 Angstrom unit= 1X10-8 centimeters
When an atom loses an electron(or shell) the proton has a greater pull on the electrons and thus the atom becomes “tighter” AKA radius decreases.
Thus, positive ions have smaller radii than neutral atoms or negative ions.
