Atomic Structure
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angle of deflection e- deflected to +ve proton deflected to -ve
charge ÷ mass (nucleon number) protons deflected more as heavier than electrons!!
why is 4s orbital filled up first and e- from 4s removed first?
• 4s orbital has a lower energy level than the 3d orbital • e- from 4s orbitals (higher energy) removed first as 4s e- experience more shielding eff than 3d orbital
compare sim and diff of 2s and 2p orbital
• both are found in the same principal quantum shell • 2s is spherical shape while 2p is dumb-bell shape
why e- in Cr occupy 3d orbital first?
more stable as inter-electronic repulsion in 4s orbital minimised as both 3d and 4s orbitals have one e- each all other elements e- occupy 4s orbitals first
why e- in Cu occupy 3d orbitals first?
more stable as there is symmetrical charge distribution in the fully filled 3d subshell (not orbitals) all other elements e- occupy 4s orbitals first
why atomic radius decrease across period?
• no. of electronic shell remain same • proton no. up, nuclear charge up • e- up but shielding eff same as e- added to same outermost shell • eff nuclear charge up • electrostatic attraction between valence e- and nucleus up • size of electron cloud down
why atomic radius increase down the group?
• no. of electronic shells ↑ • distance between valence e- and nucleus ↑ • shielding experience by valence e- ↑ • even tho nuclear charge up, electrostatic attraction between valence e- and nucleus ↓ • size of electron cloud ↑
why radius of cation smaller than anion? radius always talk about e- cloud
• both got same nuclear charge • cation got one less electron shell • electrostatic attraction between valence e- and nucleus ↑ • size of electron cloud ↓ same nuclear charge as no. of proton same for both! cation (positive charge) as electrons are removed
why first ionisation energy increase across the period? always talk about shielding eff for ionisation energy!
• no. of proton ↑, nuclear charge ↑ • inner electronic shell remains same • shielding eff same as e- added to same outermost shell • eff nuclear charge up • electrostatic attraction between valence e- and nucleus up • more energy required to remove valence e-
why ionisation energy decrease down the group? always talk about shielding eff for ionisation energy!
• no. of electronic shells ↑ • distance between valence e- and nucleus up • shielding eff experience by valence e- ↑ • even tho nuclear charge up, electrostatic attraction between valence e- and nucleus ↓ • energy required to remove valence e- ↓
why does ionisation energy decrease from group 2 to group 13? Al (group 13) Mg (group 2)
• electrons removed from 3p orbital from Al is at a higher energy level than 3s e- removed from Mg • lesser energy required to remove 3p electron than 3s electron • first IE of Al is lower than Mg
why does ionisation energy decrease from group 15 to group 16? S (group 16) P (group 15)
• 3p electron removed from S is a paired electron • 3p electron removed from P is unpaired electron • inter-electronic repulsion present between paired e- in the same orbital • lesser energy required to remove paired 3p electron from S
why successive ionisation energy of element increases? IMPORTANT!!!!
why increase: * first e- removed is from neutral atom * successive e- removed is from ion of increasing positive charge with same nuclear charge * electrostatic attraction between the nucleus and the remaining electrons increases * increase in energy required to remove each subsequent electron huge increase: * e- removed from an inner principal quantum shell of lower energy * e- removed experience lesser shielding effect * more energy required to remove
simi is electronegativity?
the ability to attract bonding electrons
why electronegativity increase across period? talk about electrostatic attraction b/w bonding e- and nucleus
• electronic shell same • no. of proton ↑, nuclear charge ↑ • e- up but shielding eff same as e- added to same outermost shell • eff nuclear charge up • electrostatic attraction between bonding e- and nucleus up • electronegativity increase across period
why electronegativity decrease down the group? talk about electrostatic attraction b/w bonding e- and nucleus
• no. of electronic shells ↑ • distance between valence e- and nucleus ↑ • shielding experience by valence e- ↑ • even tho nuclear charge ↑, electrostatic attraction between bonding e- and nucleus ↓ • electronegativity decrease down the group