Chem Periodic Trends

nuclear charge

number of protons

Zeff

harder to lose electrons

S has a greater zeff →greater coulumbic attractive force between its nuc and valence e- shell

Across a periodic table

Zeff increases from left to right, n stays the same

Down periodic table

nuclear charge increases, n increases as you go down

Explaining trends

Same

difference

CAF

trend

Atomic radius Row comparion

decreases going from left to right

the e- cloud is pulled in closer resulting in a smaller atomic force

Atomic radius column comparison

increases going down periodic table

n = 2 vs n = 6

n=6 has a greater distance between its nuc and valence e- shell

the e cloud expands resulting in a larger atomic radius

CAF

high zeff = larger CAF bc increases going left to right \

high n = lower CAF bc greater distance between nuc and valence e- shell

Ionic radius

protons vs. neutrons → e-/e- repulsion, nuclear charge, energy levels

high nuc charge (protons) → small ionic radius

high e-/e- repulsion (e-)→ high ionic radius

electronegativity

row comparison: Atoms that have a larger zeff will have greater EN

Coulomb comparison: smaller n will have greater EN

Ionization Energy

p+ to e- ration

Row: Zeff increases left to right → high ionization energy

Coulomb: ionization decreases going down → bigger n = less ionization

harder to remove e- from a positively charged ion Ni+

nm

high nm →less energy

Transition metals configs

remove e- from the highest energy level 4s 5s S first

Diamagnetic

NO UNPAIRED electrons/spins PAIRED Di = 2

Paramagnetism

contains UNPAIRED spins

1 or more e- unpaired

aufbau principal

electrons fill lower energy levels first then fill higher ones

1s then 2s then 3s

Hunds rule

when e- occupy orbitals of equal energy, one e- enters each orbital until all orbitals contain e- before doubling up

Pauli exclusion principal

an individual orbital may only hold 2 e- max