Atomic Struc Flashcards
Defn of atom
Atom is the smallest particle found in an element that can take part in a chemical rctn
Subatomic particle - location, relative mass, relative charge, symbol
E- in orbitals around nucleus, 1/1840 , -1, (0 -1) e
Neutron - nucleus, 1, 0, (1 0) n
Proton -nuclues, 1, +1, (1 1) p
Behaviour of subatomic particles in an electric field (3)
- Same speed
- diff direction of deflection
- diff angle of deflection
how to find angle of deflection and stuff (formula)
angle of deflection prop. to | q/m | when solving qn use the constant k
what is a nuclide
any species of given mass no. and atomic no. (eg hydrogen - 1) - elemental name & mass no
What is nucleon no.
mass no
what is mass no.
nucleon no.
What is atomic no.
proton no.
sig of atomic no.
determines the identity of an atom
isotopes & their properties
same no. of protons/e- but diff neutrons - same chem properties n diff/masses/phy properties
How to solve (235 92) U + (1 0) n -> Y + (90 36) Kr + 2 (1 0) n nucleon no. of Y = Proton no. of Y = Hence Y is =
Nucleon no. of Y = 235+1-90-2 = 144
Proton no. of Y = 92-36 = 56
Hence Y = (144 56) Ba
Principle quantum shell, All the subshells, no. of orbitals, types of orbitals - name, shape, direction, size
Subshells: s, p, d, f
S: 1 - spherical shape, non directional
P: 3 -dumbbell shape, directional as the e- density is concentrated in certain directed along…axes
D: 5 -
d xz & d xy & d yz - 3 orbitals with similar 4-loped shape, orbitals have their lobes pointing b/w the axes
d x^2 - y^2 - 4 lobed shape, lobes aligned along the x & y axes
d z^2 - dumbbell shaped surrounded by a small doughnut shaped ring at its waist, orbital is aligned along the z axis
the greater the value of n … (4)
further the shell is from the nucleus, higher the energy lvl of the shell
higher the energy lvl of the shell/e-
weaker the electrostatic attraction b/w nuceus and e-
larger size of orbital
energy lvl diagram & the exception
4s<3d
3 basic rules to write e- configuration
Aufbau principle - e- fill orbitals from the lowest energy orbital upwards
Hund’s rule - orbitals of a subshell must be occupied singly by an e- of parallel spins before pairing can occur
Pauli exclusion principle - each orbital can hold a max of 2 e- and they must be of opp. spins
why are paired e- stable
when they spin in opp directions, the magnetic attraction which results from their opp spins can counterbalance the electrical repulsion which results from their identical charges
2 anomalous e- configuration and why are they more stable ( general reason and indiv reason)
Cr & Cu - a ‘d’ subshell that is half-fulled or full is more stable -
for Cr: as 3d & 4s are abt equal in energy by the time Cr is reached, so by having 1 e- each in the 4d and 4s orbitals, inter-electronic repulsion is minimized
For Cu: the fully filled 3d subshell is unusually stable due to the symmetrical charge distribution around the metal center
excited state
one or more e- absorb energy and are promoted to a higher energy lvl
are 4s e- lost before or after 3d e-? and why
once e- occupy the inner 3d orbitals, they provide some shielding for the outermost 4s e- hence they repel the 4s e- to a slightly higher energy lvl
isoelectronic species
species with the same total no. of e-
e- configuration from the periodic table
s- block - ns^1 ns&2
d-block - (n-1)d1 ns^y - the 1 is starting from the first transition metal
p-block - ns^2np^1 -> ns^2np^6
Defn of atomic radius
Half the shortest inter-nuclear dist found in the struc of the element
Variation in atomic radii across period
DECREASE as
No.of e- shells remain the same
no. of protons, hence nuclear charge increases
e- increase but since they are added to the valence shell, the shielding effect remains approx const
effective nuclear charge increases
electrostatic attraction b/w nucleus and valence e- increases
decrease in size of e- cloud
Variation in atomic radii down grp
INCREASE
although protons increase, nuclear charge increases
no. of e- shell increases, dist b/w nucleus and valence e- increase
hence, the electrostatic attraction b/w the nucleus and the valence e- decreased
increase in size of e- cloud
