lecture 1 Flashcards
1
Q
what are the five atomic models?
A
- solid sphere model by Dalton
- plum pudding model by Thomson
- nuclear model by Rutherford
- planetary model by Niels Bohr
- quantum model by schrodinger
2
Q
what are the four quantum numbers?
A
- n=the principal quantum number , describes the distance/energy of the orbital to the nucleus
- l=the angular momentum, describes the shape of the orbitals and is limited by the value of n
- m=the magnetic quantum number, describes how each orbital is oriented in space and is defined by the value of l
- s=the spin quantum number, defines the direction at which an electron in an orbital is spinning in a magnetic field
3
Q
rules for filling electronic configuration:
A
- Aufbau principle; fill low to high energy
- pauli exclusion principle: max two electrons per orbital
- Hund’s rule: fill degenerate orbitals with one electron each before pairing
4
Q
what are nodes?
A
- the boundary between phases is called a node; it can be a curved surface or a flat plane.
- nodes are where both the wave function and the probability of finding an electron are zero.
5
Q
characteristics of s-orbitals?
A
- s-orbitals are spherically symmetric about the nucleus
- 1s orbital has no nodal plane or surface; 2s orbital has one spherical nodal surface
- l=0, therefore m=0, only one orientation for s orbitals
6
Q
characteristics of p-orbitals?
A
- p-orbitals are not spherically symmetric
- each p-orbital has a nodal plane
- p-orbitals: l=1, therefore m=-1,0,+1, three orientations for p-orbitals
7
Q
generally, number of covalent bonds =
A
number of electrons needed to reach an octet
8
Q
what is the difference between sigma-bond and pi-bond?
A
- sigma-bond is cylindrically symmetrical around bond axis
2. pi-bond is above and below (and left and right) of sigma-bond axis (not cylindrically symmetrical)
9
Q
flaws of valence bond theory?
A
it does not take into account about orbital phases
