5.3 atomic structure pt1 🏠

Question 1

how to calculate angle of deflection?

Answer 1

charge / mass

Question 2

define atomic number

Answer 2

atomic number is the number of protons in an atom

Question 3

define nucleon number

Answer 3

nucleon number is the total number of protoms and neutrons in an atom

Question 4

define isotopes

Answer 4

isotopes are atoms of the same element with the same number of protons but different number of neutrons

Question 5

define orbital

Answer 5

an orbital is a region of space around the nucleus where there is 90% probability of locating the electrons in this region

Question 6

define electronic structure

Answer 6

electronic structure is the arrangement of electrons in their orbitals in an atom

Question 7

what is principal quantum number?

Answer 7

the average distance of the orbitals from the nucleus (higher n, higher energy level)

Question 8

what does a subshell contain?

Answer 8

a subshell contains a group of degenerate atomic orbitals with different orientation in space

Question 9

what is the maximum number of electrons within each subshell?

Answer 9

s: 2, p: 6, d: 10, f: 14

Question 10

name the direction and shape of s,p,d orbitals

Answer 10

s: non-directional and spherical in shape
p: directional and dumbell in shape
d: directional

Question 11

name the s,p,d orbitals

Answer 11

s: s
p: px, py, pz
d: dxy, dxz, dyz, dx2-y2, dz2

Question 12

what is the maximum number of electrons within each shell?

Answer 12

1: 2
2: 8
3: 18
4: 32

Question 13

things to take note when drawing energy level diagram

Answer 13

• energy gap between 1 & 2 big, 2 & 3 medium, 3 & 4 barely
• empty 4s lower than empty 3d

Question 14

why are electrons first removed from filled 4s than filled3d?

Answer 14

when both 3d and 4s orbitals are filled, the 4s electrons are repelled by the 3d electrons, hence 4s electrons would possess higher energy

Question 15

state Hund’s Rule

Answer 15

electrons are added into orbitals of a subshell singly first with parallel spins before pairing takes place, posiitoned as far apart as possible to minimise inter-electronic repulsion

Question 16

what are the exceptions to Hund’s rule and why?

Answer 16

chromium Cr and copper Cu, because fully filled > half filled > partially filled

Question 17

how do you determine the group an element belongs to based on successive ionisation energy values? (for IE jump largest between 2nd and 3rd)

Answer 17

given that the largest increase in ionisation energy is found between 2nd and 3rd IE, the thid electron is removed from an inner shell while the second electron is removed from the valence shell. the element has 2 valence electrons and belongs to group 2.

Question 18

what are the exceptions to IE increasing across period 3 and why?

Answer 18

1. 1st IE of Mg > Al: smaller amount of energy is required to remove the 2p electron in Al which is of higher energy than the 2s electron in Mg
2. 1st IE of P > S: there exists inter-electronic repulsion between the paired 3p electrons in S. smaller amount of energy is required to remove the paired 3p ellectron in S than the unpaired 3p electron in P