Atomic Structure

Question 1

Isotopes

Answer 1

atoms of the same element which contains same number of protons and electrons but different number of neutrons

Question 2

first ionisation energy

Answer 2

energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of singly charged gaseous cations

Question 3

factors affecting ionisation energy

Answer 3

1. Nuclear charge
   number of proton increase, nuclear charge increase, greater electrostatic forces of attraction between nucleus and valence electron
2. Shielding effect
   number of inner shell electrons increases, less attraction between nucleus and electrons
3. Distance of electron fr nucleus
   electron in p subshell has a higher energy than s subshell
4. inter-electronic repulsion between paired electron
   less attraction between nucleus and electron

Question 4

Trend of 1st ionisation energy across period

Answer 4

General increase:
number of proton in the nucleus increase, nuclear charge increases, same number of inner shell electrons hence shielding effect approximately constant, effective nuclear charge increases, esfoa increases, more energy needed to remove the valence electron, IE increase

Group 2 n 13
less energy is needed to remove the p electron which is at a higher energy level than the s electron

Group 15 n 16
presence of inter-electronic repulsion between the paired p electrons, less energy is required to remove the paired p electron than the unpaired p electron

Big dip
additional quantum shell, large increase in shielding effect

Question 5

Trend of ionisation energy down the group

Answer 5

general decrease: distance between electron to be removed and nucleus increases, less electrostatic forces of attraction

Question 6

trend in successive ionisation energy

Answer 6

increases: as electron is removed, shielding effect decreases while nuclear charge remains unchanged as number of proton remains unchanged, hence greater electrostatic forces of attraction

large increase in IE represent a change in principal quantum shell:
electron is removed from an inner principal quantum shell which is closer to the nucleus, hence experiences strong esfoa

Question 7

trends of atomic radii/ionic radii/electronegativity across period

Answer 7

atomic/ionic radii generally decreases
electronegativity increases:
NC increase as number of proton increases, SE is similar as inner shell electrons is the same, ENC increase, greater esfoa

Question 8

trends of atomic radii/ionic radii/electronegativity down the group

Answer 8

atomic/ionic radii increase
electronegativity decrease:
distance between electron to be removed and nucleus increases, lesser esfoa