atomic structure

Question 1

What are the relative charges and masses of protons neutrons and electrons?

Answer 1

P mass: 1, P charge : +1
N mass: 1, N charge: 0
e- mass: 1/1836 (very neglible0, e- charge: -1

Question 2

p, n and e- in a beam and angle of deflection

Answer 2

opposites attract, neutral no attract

angle of deflection ∝ |charge|/mass ∴ e- deflects at a greater extent than protons

Question 3

Isotopes

Answer 3

Isotopes are atoms of same element having same atomic number (number of protons) but different number of neutrons

Question 4

to determine energy level

Answer 4

shell: 1,2,3…
subshell: s,p,d -> group of orbitals with same energy level
orbital: px, py, pd, dxy, dyz, dxz, d x^2-y^2, dz^2 -> specific only when needed

Question 5

shapes of s,p orbitals

Answer 5

s: spherical in shape, non directional (flat on plane)
p: dumbell shape, lines along the x,y,z axes

Question 6

to determine electronic configuration

Answer 6

• 2 e- per orbital
• 1s2, 2s2, 2p6, 3s2, 3p6, 3d10
• e- goes to the lowest energy orbital, but removed from highest energy orbital
• elements in period 3 can expand octet configuration due to presence of vacant and energetically accessible d orbitals
• all orbitals must be filled with at least 1 e- before getting 2
• 4s<3d orbitals when unoccupied hence 4s will be filled first, but 3d>4s after filling hence remove from 3d

Question 7

to determine ion configuration

Answer 7

• get its atom’s config then work backwards

Question 8

exception to configurations (hint all has to do with 3d orbitals)

Answer 8

Cr: half filled 3d is more stable than filled 4s
Cu: fully filled 3d is more stable than having last 3d orbital have 1e-

Question 9

define first ionisation energy

Answer 9

the first ionisation energy of an (__) ELEMENT is the amount of energy required to remove 1 mole of electrons from 1 mole of gaseous (__) ATOMS to form 1 mole of singly charged gaseous (__) CATIONS

Question 10

define second ionisation energy

Answer 10

the second ionisation energy of an (__) element is the amount of energy required to remove 1 mole of electrons from 1 mole of singly-charged gaseous cation (__) to form one mole of doubly-charged gaseous cation (__)

Question 11

is ionisation energy endo or exo?

Answer 11

Ionisation energy is endothermic as it is to overcome the attraction between the positively charged nucleus and e- hence energy must be released

∴ more endothermic = greater ionisation energy

Question 12

what affects ionisation energy

Answer 12

effective nuclear charge=

nuclear charge: higher number of protons -> greater nuclear charge
+
sheilding effect: greater number of e- shells -> greater shielding experienced by valence e-

Question 13

trends and exceptions of i.e. across a period

Answer 13

Generally increasing trend
Exceptions:
- grp2->grp3 due to less energy to remove 2/3p e- increased shielding provided by filled 2/3s subshell
- grp5->grp6 due to less energy required to remove paired 2/3px electron due to inter electron repulsion (must show px,py,pz config to prove)

Question 14

successive i.e. of an atom trends

Answer 14

• successive i.e. increase after removal of e- as there are less e- than protons and remaing e- will be more strongly attracted to constant positive charge
• large increase in ionisation energy between 2nd and 3rd i.e. (or whenever removing from inner energy shell)
• largest increase -> removing from the very innermost energy shell