Chemistry - Chapter 2

atoms are made up of…

protons, neutrons, and electrons

what subatomic particle has the least mass?

electrons (proton is much more larger —> making nucleus bigger)

which subatomic particle has the most mass?

neutron

equation for number of atoms

total mass/mass per atom

atomic number

# of protons

mass number

protons and neutrons

bohr’s radius

possible distance that the electron and nucleus (in a hydrogen atom) can get

why is there a negative sign in bohr’s equation

it shows the attractive force between the protons in the nucleus and electrons

states that are greater than n>1 are..

excited states

states that are n=1 are…

ground state

energy difference calculation

n₁ = final

n₂ = inital

n = ?

• principal quantum number

• distance from nucleus

• common value of n = same shell

• in hydrogen all orbitals that have the same n have the same energy

what happens as an electron moves farther away from the nucleus (energy, n, stability)

• more energy

• n is getting larger

• less stable b/c not as attracted to the nucleus

energy difference/ionization energy

how much energy is needed to move an electron to different states/levels

Schrödinger’s equation for wave function

|Ψ|²

probability density (likelihood of locating an electron in a given space)

• never negative

radial probability density

• probability of finding the electron at a certain distance r

• as r increase the possibility of finding the electron decreases

• greatest at r=0 b/c the electrons are extremely close to the nucleus

l

• angular momentum

  • rotational motion

• electron is in different angles

• n-1

  • “l” can be anything less than n-1

“l” values (the letters)

• s = 0

• p = 1

• d = 2

• f = 3

orbital penetration

• how close an electron can get to the nucleus

• the closer the electron can get to the nucleus the more it wants to penetrate

• as “l” increases the orbital penetration decreases

  • this is because they are getting farther away from the nucleus and having to penetrate more shielding electrons

• as “l” decreases the more orbital penetration and thus more stable

m_l

• how the orbital is tilted on the nucleus

  • orientation (z, x, y)

  • tells which axis the orbital is on

• each negative number of the “l” values

• s is spherical so no need for m_l because it deals with orientation

• the total number of all the m_l show you how many orbitals you will have

radial nodes

• zero probability of finding the electron

• n - l - 1

electron affinity

• gaining an electron

ionization energy

• energy needed to pull away an electron

angular nodes

• value of “l”

total number of nodes

n - 1

how to get each node

radial = n - l - 1

angular = l

total number = n-1

radial wavefunction

• shows the strength of the electron at that distance

• how electron’s probability changes with distance

orbital

region WITHIN a shell where an electron can be found

• an atomic orbital needs (n, l, m_l)

• the actual spaces

m_s

• spin quantum number

• +½ or -½

• in one orbital if there are two electrons one gets ½ the other gets -½

how to find energy of an electron

E_n= - R (1/n²)

• only for single electron atoms

• doesn’t take into account repulsion

the larger the negative number… (more or less energy)

less energy = more stable

if more nodes…(higher or lower energy state)

higher energy state

• since higher l, which also means higher n

what did bohr suggest?

• electrons travel in fixed paths

• good contribution 

  • each orbit has an energy associated with it

  • as you move further away from nucleus you are getting closer to zero and increasing your energy (less negative)

as energy gets more negative is it harder or easier to remove?

harder because the energy is decreasing

ψ v. |ψ|²

ψ 

• probability of finding an electron in an atom

|ψ|²

• probability of finding an electron in a given region

as n increases…(relation to graph)

• the height of each peak gets smaller (since probability is spread over large distance)

• electron has probability over a wide region

penetration general rule

more penetration → lower in energy → more stable

• why 2s has a peak farther out because of its penetration to the nucleus