ochem chapter one: structure determines properties

what do quantum numbers describe

how electrons move/ behave as waves

what is the principle quantum number and what is the relationship between its value, energy, and its distance from the nucleus

n= 1, 2, 3… (some integer)

the higher the value of n, the higher the energy and the further away from the nucleus the electron is

what is the Orbital Angular Momentum Quantum Number and what does it tell us

l= an integer (the value of n-1. that number is the maximum)

this tells us the shape of the electron wave/ orbital

ex: if n=2, ℓ= 2-1 → ℓ= 0, 1 (

Magnetic Quantum Number

m_l = 0 ± 1, ± 2, … ± 𝓁

the number of values corresponds to the number of orientations in space for a given orbital

so if 𝓁= 0 (s orbital) then m_l= 0 (ONE value for m_l means ONE orientation in space)

if 𝓁= 0, AND ± 1

visualize 𝓁=1 m_𝓁 =0, ±1

𝓁= 1 so it is a p-orbital

since m_𝓁 has three values (0, -1, +1) then the orientations in space for the given orbital are 3

a p-orbital looks like a figure 8 (∞)

we can look at this on different planes (px, py, and pz)

think of it as a standing wave between two fixed points

Magnetic Spin Quantum Number

m_s = +1/2 (↑) or -1/2 (↓)

tells us the spin orientation for an electron

electron configuration

we can add elecrtons to orbitals to get the proper configuration for various elements

any orbital holds max 2 electrons __ __ __

Pauli Exclusion Principle

part of electron configuration

avoid having a situation where two electrons have the same set of quantum numbers (like two up spins or two down spins)

Hunds Rule

(electron configuration)

for degenerate orbitals, add electrons to empty orbitals first with parallel spins before we start pairing up

electronegativity

the ability of an element to pull electron density towards itself in a bond .

formal charge

method for counting electrons based on the idea that electrons in bonds are being equally shared

count the total number of lines and dots on an element and compare it to the number of valence electrons it started with.

if lines and dots are bigger than Ve-, then the element has a negative charge.

net charge

the sum of all formal charges

we want negative charges on electronegative elements

positive charges are best on less electronegative elements

Ka and acid strength

higher the value for Ka, the stronger the acid

an strong acid has a Ka larger than 1

pKa and acid strength

the lower the value of pKa, the stronger the acid

electronegativity and acid strength

the more electronegative the central atom is (that the H is bonded to), the stronger the acidity

can look at the second row of the periodic table

functional groups definition

an atom or group of atoms that determine how a molecule reacts and what its properties are. this is how we can classify organic molecules

R-group

any generic alkyl group