Unit 2 Flashcards
Bonds
Atoms bond in order to reach a stable 8 valence state
Ionic Bond
Electrostatic forces held together ions.
Generally between metals and nonmetals
Metallic Bond
Bons between metals that are neither covalent or ionic: the e- is delocalized so they are free to roam - like a soup
Covalent Bond
Sharing electrons and forming a molecule
generally non-metal and non-metal
Lattice
structure of a molecule
Network covalent bonds
Lattice of covalent bonds making a 3D structure
What are some characteristics of Ionic Bonds (3)
- Strong lattice structure
- Solid at room temp
- High melting and boiling points
What are some factors for melting points? (2)
- Greater charge = greater melting point
- Smaller size = greater melting point
What are some factors for bond energies? (3)
- Greater charge = greater bond energy
- Smaller size = greater bond energy
- More bonds = higher energy
(Greater bond order)
What are some characteristics of metallic bonds? (2)
- malleable and ductile
- they can form alloys
Alloy
combination of elements where at least one is a metal
What are the two types of Alloys and explain
- Interstitial alloy - different radii sizes
- subsitual alloy - similar radii sizes
What are some characteristics of Network Covalent structures? (2)
- Hard
- High melting and boiling points
Aqueous
a substance put in H2O
Bond Order:
(total # of bonds)/(# of atoms)
What are the three rules to keep in mind when you draw Lewis Dot Structures?
- Least Electronegative = central atom
- Add extra e- till valence shells are finished
- Add extra e- to central atom
What is the maximum amount of e- the central atom can have?
No more than 12
They can take up to 12 due to the d-block
Resonance Forms
A bond can go anywhere - in reality, the e- is at all of those locations the equal amount of time
Incomplete Octets (2)
- B and Al - stable with 6 e-
- H - stable with 2 e-
Expanded octets
there can be up to 12 e- ONLY AND ONLY IF
n = 3
NEVER
n = 2
n = 1
Formal Charge
(# of valence e-) - (# of valence e- assigned)
PER ATOM
How do I know if an atom is stable?
If the formal charge per atom is 0 or close to 0
VSEPR
Valence electron model that predicts the three dimensional geometry of the molecule
For formal charge, a lone pair stands for
2 e-
For formal charge, a covalent bond stands for
1 e-
Repulsion Model for bonds and e-
single < double < triple < lone
Metal characteristics (3)
- Malleable
- Great conductors
- Solid at room temp
Non metals Characteristics
- Bad conductors
- gases at room temp
What are two components of bond energy?
- Higher number of bonds - higher energy
- smaller atoms - higher energy
Smaller atoms mean…
Smaller distance between atoms
According to the Coulomb’s law, what type of atoms are harder to pull apart?
- Smaller
- More charge
What are the two types of covalent bonds?
- pi
- sigma
The first bond in a covalent is ALWAYS…
sigma
everything else is pi
The more bonds, the higher the…
energy
If there are more than two structures having a -1 charge on either atom, how do you determine which is correct?
The more electronegative atom takes the -1
example obvi
In a VSEPR model, how do you determine the geometry of the atom as a whole?
- determine the geometry of the central atom
- Determine the molecular geometry of the molecule by ignoring any lone pairs on the central atom.
Dipole moment
measurement of polarity of two atoms
What is the equation for Dipole moment?
u = QD
Q = magnitude of a charge in Coulombs
D = magnitude of distance in Meters
divide by 1 Debye
What is one Debye equal to?
3.34 X 10^-30 C . m
What is one electron equal to in Couloumbs
1.60 x 10^-19
Hybirdization
Since s and p (etc.) are in different energy states, we hybridize them
S character, P character is depended on…
the % of each of them
The more S character, the…..
smaller and tighter the bond
Steric Number calculation
(# of sigma bonds) + (# lone pairs)
calculated on central atom
Steric Number calculates what?
the number of hybridized orbitals
What kind of bonds are not hybridized?
Pi bonds
Higher bond order means…
shorter bonds
