atomic structure prt1

Question 1

name the 3 models of atoms and describe them

Answer 1

1. Nucleus tiny core - (+)tive nucleus, consisting of protons and neutrons surrounded by a cloud of electrons
2. Classic model - electron orbiting the nucleus
3. the wave mechanics model - electron is a wave, where the negative charge is spread out like a fog - fog is DENSE near the nucleus ( higher electron density ) and THIN further away ( low electron density )

Question 2

why do we need 4 quantum numbers

Answer 2

space is 3D, and electrons have a spin (4th number)

Question 3

what is the 4th property of electrons

Answer 3

spin ( ms )

Question 4

define the 4 quantum numbers and what they mean, and why

Answer 4

n = principle quantum number ( orbit size) 
l = angular momentum quantum number (orbital shape) 
ml = magnetic quantum number (orientation of orbital)  
ms =  spin quantum number ( up or down )

Question 5

how many different orientations of a 2p orbitals are there? name the different orbitals

Answer 5

( ml ) +1, 0, -1
3 different orientations
2px, 2py, 2pz

Question 6

what is the nodal plane ?

Answer 6

the plane at which the probability of finding an electron is 0

Question 7

what is the nodal plane of these p orbitals
2py
2px
2pz

Answer 7

2py - xz
2px - zy
2pz - xy

Question 8

how many different orientations of d - oribitals are there? name the different orbitals

Answer 8

ml = +2, +1, 0, -1, -2
5 different orientations
dxy, dxz, dyz, dx^2-y^2, dz^2

Question 9

in terms of changing sign, how are p orbitals and d orbitals different?

Answer 9

in p-orbitals the opposite lobes have the different sign

in d-orbitals the opposite lobes are the same sign

Question 10

what is shielding?

Answer 10

where the s-electrons repel all other electrons.

s-orbitals have more electron density near the nucleus

Question 11

what is the effective nuclear charge?

Answer 11

The effective nuclear charge is the net positive charge experienced by an electron

Question 12

what is penetration?

Answer 12

for the same value of n, s-orbitals have more electron density than p orbitals, which has more than d-orbitals (ns < np