atomic structure

Question 1

Explain the general trend for atomic radii and I.E

Answer 1

Across the period,
1. no. of p increases so Z increases
2. shielding effect remains approximately constant since no. of inner electrons remains the same
3. effective nuclear charge increases
4. stronger electrostatic forces of attraction between the nuclues and the valuence electrons

[atomic radii] valence electrons are closer to the nucleus. hence atomic radius decreases

[I.E] more energy required to remove the valence electron

Question 2

I.E exceptions

Answer 2

1st IE for Al < Mg as the 3p e in Al is further away from the nucleus compared to 3s e in Mg

1st IE of S < P as inter-electronic repulsion is present in the doubly-filled 3p orbital of S atom compared to the singly-filled 3p orbital of P atom

Question 3

significant jumps in IE (eg. from 2nd to 3rd IE)

Answer 3

1. Observation: 3rd e removed from inner shell
2. This means: 3rd e experiences a stronger electrostatic forces of attraction with the nucleus compared to…
3. more energy required to remove 3rd e

Question 4

(a) identify and describe protons, neutrons and electrons in terms of their relative charges and relative masses

Answer 4

protons: +1, 1

neutrons: 0,1

electrons: -1, 1/1840

Question 5

(b) deduce the behaviour of beams of protons, neutrons and electrons in an electric field

Answer 5

protons: deflected towards the negative polarity

neutrons: -

electrons: deflected towards the positive polarity

Question 6

angle of deflection

Answer 6

charge/mass

Question 7

define isotopes

Answer 7

same p
diff n

Question 8

(g) describe the shapes of s, p and d orbitals

Answer 8

s orbital: non-directional and spherical

p orbital: directional and dumb-bell

d orbital: directional

Question 9

why 4s orbital is removed first than 3d when 4s2 electrons are added first?

Answer 9

when both 3d and 4s orbitals are filled, the 4s electrons are repelled by the 3d electrons. 4s electrons would thus posses higher energy

Question 10

how are electrons added into the orbitals?

Answer 10

singly first with parallel spins before pairing takes place

Question 10

each orbital can hold a max of __ electrons in __ spins

Answer 10

2, opposite

Question 11

anomalous electronic configurations: Cr & Cu

Answer 11

[3d5,4s1], [3d10,4s1]configuration is found to be more stable than (expected configuration)