The Solid State Flashcards
The stronger the intermolecular forces, the ___________ movement of the particles
Slower
What are the properties of amorphous solids?
- random arrangement of particles
- particles have no orderly structure
- macroscopic structures lack well defined faces and shapes
- many are mixtures of molecules that do not stack up well together
- glass and rubber are examples
What are the properties of Crystalline Solids?
- atoms, ions, or molecules are arranged in an orderly fashion that follows a pattern of repetition in three dimensions
- macroscopic structures usually have flat surfaces that make definite angles to one another
- ionic solids and quarts are examples
Segments in crystalline solids that repeat in three dimensions
Unit cells
In liquids particles go thorough ____________ meaning they move around
Translation
The corners of the cubes
Lattice points
This unit cell contains:
8 corners x 1/8 of an atom
= 1 atom/unit cell
Simple cubic
This unit cell contains:
8 corners x 1/8 of an atom + 1 central
=2 atoms/unit cell
Body centered cubic
This unit cell contains:
8 corners x 1/8 of an atom + 6 faces x 1/2 of an atom
=4 atoms/unit cell
Face centered cube
What are the properties of molecular solids?
- consists of nonmetals, diatomic elements, or compounds composed of two or more nonmetals
- normally do not conduct electricity
- covalently bonded units are held together by weak intermolecular forces
- soft
- have low melting points
Why do molecular solids normally not conduct electricity
Electrons are held within the covalent bonds of each molecule
What is an example of a molecular solid?
I2
___________ fats have stronger dispersion forces, and are solid at room temperature
Unsaturated
Why do unsaturated fats have weaker dispersion forces?
A double bond bends the carbon, causing the molecule to be sp2 hybridized, therefore being trigonal planar
What is an example of a molecular solid?
Wax
One or two nonmetals held together by networks of covalent bonds instead of intermolecular forces
Covalent network solids
What are the properties of a covalent network solid?
- very hard
- very high melting points
Why are covalent network solids normally very hard?
-atoms are covalently bonded with fixed bond angles
In graphite, each carbons forms three _____ hybrid orbitals that bond with three other carbon atoms
Sp2
Graphite and diamond are __________ of each other
Allotropes
Why can sheets of graphite slide over each other so easily?
Weak pi bonds and london dispersion forces
Why does graphite have a high melting point?
The covalent bonds between carbon in each later are relatively strong
In diamond, many carbon atoms bond together with _______ hybrid orbitals
Sp3
What is the molecular geometry of diamond?
Tetrahedral
In diamonds each carbon makes a single covalent bond with ___ other carbon atoms
4
Other common covalent network solids include _________ and __________
SiO2 and Si
Si is a ______________
Semiconductor
Why is bonding in metallic solids not covalent?
Not enough electrons to fill octets
How does bonding in metallic solids work?
Attractions between nuclei and delocalized valence electrons move throughout the structure
Bond strength in metallic solids __________ as the number of bonding electrons increases
Increases
Why so metals bend, not break when hit with a hammer?
There are no directional bonds
Describe the electron sea model in metallic bonding
Nuclei and inner shells are stationary, while valence electrons are free to move throughout the solid
What are properties of metallic solids?
- conduct electricity
- conduct heat
- malleable and ductile
- lack directional bonds
Why do saturated fats have stronger London dispersion forces?
It’s linear shape is good for stacking, meaning there are many points of contact between molecules
Why are diamonds so hard?
- Diamonds are one massive molecule held together by covalent bonds
- the sp3 hybridization allows for a tetrahedral structure which is very strong
