Structure of atom Flashcards
No of e’s prop
intensity of light
KE of e’s increase with
Increase in freq of light
Lymann in
UV
Balmer in
Visible
Paschen, Brackett Pfund in
IR
Max wavelength n1,n2=
n2 = 2 and n1 = 1 in Lymann
Which spectral line has max wavelength?
1st
No of radiations emitted when e’ drops from nth level to ground level
n(n-1)/2
Bohr’s postulates
E’ revolve in circular orbits
Each orbit have fixed energy
E’ can move only in orbits with l = nh/2pi
Bohr merits
Could explain atomic spectra of H
Energy of nth orbit
En = 2.179 Z^2/(10^18 n^2) J/atom
En = -1312 Z^2/n^2 kJ/atom
-13.6 Z^2/n^2 eV/atom
If KE is x, PE is
-2x
Radius of nth orbit
rn = a(o)n^2/Z
Value of a(o)
0.529A*
Velocity of e’ in H
Vn = 2.189x10^6 Z /n
Energy of radiation emitted =
ΔE = 2.189Z^2/10^18(1/n1^2 - 1/n2^2) J
ΔE = 1312Z^2(1/n1^2 - 1/n2^2) kJ
ΔE = 13.6Z^21/n1^2 - 1/n2^2) eV
Bohr’s limitations
Failed to explain atomic spectra of multi e’ species, Zeeman & stark effect, de Broglie nature of matter
As mass increases, which nature increases
particle
Heisenburg uncertainty principl
It is impossible to determine V and position or position & momentum at the same time with accuracy
Δx.Δp = h/4pi
priniciple quantum no N starts from
1 to infinity
K, L, M, N,..
Max no of e’s in nth level
2n^2
Azhimuthal quantum no l =
0 to n-1
No of subshells in nth main shell
n
Max no of e’s in sub shell
4l + 2
Magnetic quantum no m
-l to +l
No of orbitals in subshell
2l + 1
No of orbitals in nth main shell
n^2
Possibility of finding e’s is maxm & min in
orbitals and nodes
No of spherical nodes
n-l-1
No of nodal plane
l
Total nodes
n-1
Covalent cmpds
Exist in 3 states, low MP and BP, Soluble in org solv, bad conductors
Formal charge FC =
Valence - Non bonding e’s - 1/2 bonding e’s
Incomplete octet eg
BCl3, AlCl3
Expanded octet eg
SF6, PCl5
Odd e’ molecule
NO, NO2
Formation of Xe & Kr cmpds
XeO3 & XeF2
Factors of Ionic bond
IE - decreases for e +ve atom
-ve e’ gain enthalpy of e’ -ve atom & lattice energy increases
Lattice enthalpy depends on
|Q1Q2|
Size - inverse
Factors affecting covalent nature
Size of cation - inverse
Size of anion - prop to polarisation
Charge - prop
2 e’ pair, shape
linear
3 e’ pair, shape
trigonal planar
4 e’ pair shape
tetrahedral
5 e’ pair shape
trigonal bipyramidal
Trigonal planar eg
BF3
Tetrahedral eg
CH4, NH4
Trigonal bipyramidal eg
PCl5
Octahedral eg
SF6
Hybridisation H =
1/2[V+M+A-C]
V valence, M monovalent atom, C charge of cation, A charge of anion
MOT
e’ are present in MO
MO formed are combination of at. orbitals of same energy & symmetry
MO are multi centered
No of MO =
No of AO
Energy of BMO, AO and AMO
BMO<AO< AMO
Bond order
1/2[Nb - Na]
Bond order depends on
bond len - inv
bond energy - prop
