Structure and Bonding Flashcards
Name the group 1 elements in order down the group
H, Li, Na, K, Rb, Cs, Fr
Name the group 2 elements in order down the group
Be, Mg, Ca, Sr, Ba, Ra
Name the group 3 elements in order down the group
Sc, Y
Name the group 4 elements in order down the group
Ti, Zr, Hf, Rf
Name the group 5 elements in order down the group
V, Nb, Ta, Db
Name the group 6 elements in order down the group
Cr, Mo, W, Sg
Name the group 7 elements in order down the group
Mn, Tc, Re, Bh
Name the group 8 elements in order down the group
Fe, Ru, Os, Hs
Name the group 9 elements in order down the group
Co, Rh, Ir, Mt
Name the group 10 elements in order down the group
Ni, Pd, Pt, Ds
Name the group 11 elements in order down the group
Cu, Ag, Au, Rg
Name the group 12 elements in order down the group
Zn, Cd, Hg, Cn
Name the group 13 elements in order down the group
B, Al, Ga, In, Ti, Uut
Name the group 14 elements in order down the group
C, Si, Ge, Sn, Pb, Fl
Name the group 15 elements in order down the group
N, P, As, Sb, Bi, Uup
Name the group 16 elements in order down the group
O, S, Se, Te, Po, Lv
Name the group 17 elements in order down the group
F, Cl, Br, I, At, Uus
Name the group 18 elements in order down the group
He, Ne, Ar, Kr, Xe, Rn, Uuo
Define ‘quantize’
To restrict a physical quantity to one of a fixed set of numbers
What is the experimental evidence for electrons behaving as both a particle and a wave?
The photoelectric effect - Many metals emit electrons when light shines on them. Increasing intensity of light increased number of electron emitted, but not their kinetic energy - So electrons can behave as particles
Davisson and Germer (1925): - Fired electrons at nickel - Electrons diffracted not just reflected - Diffraction is a property of waves
What is the De Broglie relation?
wavelength = h / mv
Kinetic energy =
Curvature = 2nd derivative
What is the typical bond length in a molecule?
100 pm
A very small wavelength means…
No diffraction
What is the potential energy of an electron confined to a 1D box?
0 inside the box, infinity at the walls
What is the wavefunction, ψ?
Wave height at point x
When you put an electron in a box…
It behaves as a wave
ψn(x) =
Csin(nπx / L)
L = length of box
n = quantum number
C = normaliation constant, value needed to make the integral of this 1
Energy of a wave, E =
n2h2 / 8mL2
What is a node?
Locus where the wavefunction is 0
What is ψ2?
The probability of finding the electron at that point
ψn,m(x,y) =
2/L sin(nπx/L) sin(mπy/L)
2D: En,m =
(n2 + m2)h2 / 8mL2
Quantum number n =
Orbital size quantum number - principle quantum number
Quantum number l =
Orbital shape quantum number - orbital angular momentum quantum number
Quantum number ml =
Orbital orientation quantum number - magnetic quantum number
Orbital is another word for…
Hydrogen wavefunction, ψ
What does it mean to say that the electron can behave as a wave as long as it’s a standing wave?
The wave must be continuous, and there must be an integral number of waves around the ring
2πr =
nλ
What is the radial wavefunction?
- Depends on radius, r - Quantum number n= 1,2,3,4…infinity - Uses symbol ψ(r)
What is the angular wavefunction?
- Depends on θ, ϕ - Quantum numbers l (0,1…n-1) and m (-l,….,+l) - Uses the symbol ψ(θ,ϕ)
What is needed to give a wavefunction in spherical polar coordinates?
Radius, r
Colatitude (angle down from z axis), θ
Azimuth (angle east from x-z plane), ϕ
What quantum numbers give a 1s wavefunction?
n=1, l=0, ml =0 (s means l = 0)
Radial distribution function =
4πr2ψ2
The probability of finding the electrons in all directions at that radius
How many radial nodes does an ns wavefunction have?
n-1
How many radial nodes does an np wavefunction have?
n-2
How many radial nodes does an nd wavefunction have?
n-3
Total wavefunction =
ψ(r)ψ(θ,ϕ)
Angular wavefunctions for all s wavefunctions are…
Spherical
What is the boundary surface?
A representation of the angular wavefunction that contains 90% of the electron density
What does it mean for 2 energy states to be degenerate?
They have the same energy
What is the Pauli Exclusion Principle?
No two electrons in an atom or ion can have all their quantum numbers the same
What is Hand’s rule of maximum spin multiplicity?
Lowest energy = Maximum number of parallel spins
For hydrogen, orbital energy is proportional to
-1/n2
For atoms other than hydrogen, orbital energy is proportional to
- Zeff2/n2
Order of repulsion of pairs of electrons (strongest to weakest)
Lone pair - Lone pair
Lone pair - Bonding pair
Bonding pair - Bonding pair
Shape of molecule with 2 electron pairs
Linear
Shape of molecule with 3 electron pairs
Trigonal planar
Shape of molecule with 4 electron pairs
Tetrahedral
Shape of molecule with 5 electron pairs
Trigonal bipyramid
Shape of molecule with 6 electron pairs
Octahedral
Shape of molecule with 7 electron pairs
Pentagonal bipyramid
For a trigonal bipyramid, which is the larger site?
Equatorial
For a pentagonal bipyramid, which is the larger site?
Axial
What is Bent’s rule? (VSEPR)
The smaller atom goes to the smaller site
Why do we need to create orbital hybrids?
Because for overlap we need singly occupied orbitals
What hybridisation does forming a linear molecule require?
sp
What hybridisation does forming a trignal planar molecule require?
sp2
- Taking s, px and py produces 3 hybrids at 120o in the xy plane
What hybridisation does forming a tetrahedral molecule require?
sp3
- Taking s, px, py and pz produces 4 hybrids directed at the vertices of the tetrahedron
The antibondig orbital is denoted by…
σu* or πg*
The bonding orbital is denoted by…
σg or πu
Bond order =
(no. of bonding electrons - no. of antbonding electrons) / 2
What does paramagnetic mean?
A material is paramagnetic if it attracted to a magnet because of unpaired electrons
What does diamagnetic mean?
A material is diamagnetic if it is repelled by a magnet because of paired electrons
Molecular orbitals are…
Linear combinations of atomic orbitals
Magnetic moment, χ =
diamagnetic - paramagnetic
For diatomic molecules with p orbitals, σu* =
1 /√2 [pz(a) + pz(b)]
For diatomic molecules with p orbitals, σg =
1/√2 [pz(a) - pz(b)]
For diatomic molecules with p orbitals, πu =
1/√2 [px(a) + px(b)]
For diatomic molecules with p orbitals, πg* =
1/√2 [px(a) - px(b)]
Bond order will correlate with…
Bond length and bond strength
J in SI base units
kg m2 s-2
What is excitation energy?
The energy required to move an atom to its next energy level
1 mile =
1609 m
Which is more penetrating, 2p or 2s?
2s
If an orbital is more penetrating, it feels…
A higher Zeff
What is penetration?
The attraction an orbital feels towards the nucleus
How to show if an orbital has a higher Zeff than another
Sketch the radial distribution functions, whichever has a local maximum closest to the nucelus feels a higher Zeff
State and explain for which elements sp switching occurs
B,C and N
2p orbitals are not involved with elements before B, after N, the energy gap between 2s and 2p is too large