Lecture 3- Atomic theory 3

Question 1

problem with bohr and shell model

Answer 1

• Bohrs equations that predicted the energy levels of orbits only worked for hydrogen
• PES data indicated that there are subshells within each shell
• Solution: The Quantum Mechanical Model of the Atom

Question 2

Quantum Mechanical model

Answer 2

• electrons do not follow orbit

- A wave function describes an electrons possible position in 3d space and is often called an oribal

Question 3

Differences

Answer 3

EL= size
sublevel= shape
orbital=orientation in space

Question 4

What is an orbital

Answer 4

a geographic representation of the space that an electron will occupy 90% of the time

Question 5

how many electrons in each orbital

Answer 5

s=2
p=6
d=10
f=14

Question 6

Pauli exclusion

Answer 6

each orbital can hold a maximum of two electrons that will spin in opposite directions

Question 7

Hunds rule

Answer 7

when you have more than one orbital in a subshell a single spin up electron is added to each orbital before you start adding spin down electrons

Question 8

paramagnetic atoms

Answer 8

• unpaired electrons

- magnetic moment

Question 9

diamagnetic atoms

Answer 9

• no unpaired electrons

- not magnetic

Question 10

effective nuclear charge

Answer 10

• repulsive forces caused by the shielding effect reduce the effective nuclear charge experienced by outer electrons
• attraction that the protons have to the inner electrons
• across period shielding effect stays the same since theres the same number of inner electrons but radius decreases. This can be explained with EFC since the same number of inner electrons are being attracted to more protons

Question 11

4 periodic trends

Answer 11

• atomic radii
• ionic radii
• ionization energies
• electronegativity

Question 12

Atomic radius down a group

Answer 12

• new shells added, larger orbitals
• valence electrons have more energy, less stable, and further from nucleus
• outer electrons experienced a greater she idling effect and a decreased effective nuclear charge.
• according to coulombs law, the force of attraction decreases as the distance between the electron and protons increases

Question 13

Atomic radius across period

Answer 13

• valence electrons in the same shell
• shedding effect experienced by outer electrons the same since they’re in the same energy level, but the addition of protons increases the effective nuclear charge on those electrons
• According to coulombs law, the increase in positive charge increases the force of attraction experienced by each electron , thereby decreasing the radius

Question 14

ionic radius of cations across period

Answer 14

• radii of cations decrease across for the same reasons

Question 15

ionic radius of anions across period

Answer 15

• when you encounter the first anion, the radius increase dramatically (since replusions from the additional electrons cause the electron cloud to expand) then continues to decrease