CHEMISTRY: Quiz 4

Quantum theory

particles and waves follow a different set of rules apart from the macroscopic world

wave-particle duality

electrons can exhibit wavelike behavior; a wave equation governs electron’s motion

heisenberg uncertainty principle

it is fundamentally impossible to determine simultaneously and exactly a particle’s position and momentum

schrodinger equation

thought of electron in terms of a three dimensional standing wave represented by the greek letter psi, ψ.

wavefunctions

can be used to determine the distribution of the density of electrons in relation to the nucleus in an atom

quantum mechanics

electrons in atoms can only exist in discrete energy levels but not between them

the energy of an electron in an atom is quantinized

the energy can be equal to only certain specific values and can jump from one energy level to the next but not transition smoothly or stay between the levels

energy levels labeled by n

atomic oritbal

region in an atom where electron will likely reside

angular momentum quantum number (ℓ)

defines the shape of the orbital

ℓ=0: s orbital

ℓ=1: p orbital

ℓ=2: d orbital

ℓ=3: f orbital

radial nodes

values of radius r

certain distances from the nucleus at which the probability density of finding an electron located in a particular orbital is zero

the value of the wave function is zero at this distance for this orbital

n-ℓ-1

orbital shapes

s-sphere

p-dumbell

d and f-complex

three dimensional regions where electrons are likely to be found

magnetic quantum number mℓ

depends on ℓ ; specifics the orientation of the orbital in space

one s orbital

three p orbitals

five d orbital

7 f orbitals

degeneracy

energy levels with the same principal quantum number; orbitals within the same subshells are degenerate and have the same energy

spin quantum number

describes an intrinsic rotation or spinning can spin in one of two quantized states -1/2 or +1/2

pauli exclusion principle

no two electrons in the same atom can have exactly the same set of all four quantum number; if they are located in the same orbital they must have opposite spins

principal quantum number n

the size of the orbital increases and electrons are further from the nucleus as n increases, so the attraction to the nucleus is weaker and the energy associated with the orbital is higher and less stabilized

electron configuration

arrangement of electrons in orbitals

Aufbau principle

electrons fill atomic orbitals of the lowest available energy before occupying higher-energy orbitals; continuing across the periodic table we add one electron to the sub shell of lowest available energy

Hund’s rule

every orbital in a sub shell is singly occupied with one electron before any orbital is doubly occupied, and all singly occupied orbitals must have parallel spins; the lowest energy configuration for an atom with electrons within a set of degenerate orbitals is that having the maximum number of unpaired electrons

valence electrons

electrons occupying the orbital in the outermost shell (highest value of n)

core electrons

electrons that occupy the inner shell orbitals; can be represented by noble gas electron configurations

main group elements or representative elements

the last electron added enters an s or p orbital in the outermost shell. the valence electrons for main group elements are those with the highest n level.

transition elements or transition metals

metallic elements which the last electron added enters a d orbital

inner transition elements

metallic elements in which the last electron enters the f orbital

ions

when an atom gains or loses electrons

cation

when one or more electron is removed; for main group elements electrons that were added last are the first electrons removed; for transition and inner transition metals the highest ns electrons are lost first then the d or f electrons

anion

when one or more electron is added in the order predicted by aufbau principle (fill the lowest energy orbital before moving to higher

periodic properties

size radius of atoms and ions, ionization energy, electron affinity

covalent radius

one half the distance between two nuclei of identical atoms that are joined together by a covalent bond

Effective nuclear charge, Zeff

the pull exerted on a specific electron by the nucleus, taking into account any electron-electron repulsions