Chem 1104 final

quantam-mechanical model of an atom

a model that explains how electrons exist in atoms and how those electrons determine the chemical and physical properties of elements

electronmagnetic radiation

the emission and transmission of energy in the form of electromagnetic waves

electric field

region of space where an electrically charged particle experiences a force

magnetic field

region of space where a magnetic particle experiences a force

speed of light in a vacuum

3.00 x 10^8 m/s

speed of sound

340 m/s

amplitude

the vertical distance from the middle of a wave to the peak or trough

wavelength

the distance between identical points on successive waves

intensity

the brightness of light(in a light bulb it is dim and bright)

frequency

the number of cycles (or wave crests) that pass through a stationary point in a given period of time. Hz=1 cycle

what are the components of the electromagnetic spectrum? (in order from low to high frequency

Radio, microwave, infrared, visible light, ultraviolet, x ray, gamma ray

what is the visible range (ROY G BIV)

around 400-750nm

what is the range of UV light

around 200-400 nm

what are two molecules that have the lambda max falling in the UV range

proteins and nucleic acids have got a lambda max falling within the UV range

interference

interaction of waves, including electromagnetic waves, with each other in a charcteristic way

constructive interference

if two waves of equal amplitude are in phase (peak is in line with peak or trough with trough) when they interact, a wave with twice the amplitude results

destructive interference

if two waves of equal amplitude are out of phase when they interact, the waves cancel out

diffraction

when a wave encounters an obstacle or a slit that is comparable in size to its wavelength, it bends (or diffracts)around it

interference pattern

the diffraction of light through two slits separated by a distance comparable to the wavelength of light, coupled with interference, results in an interference pattern

photoelectric effect

metal can emit electrons when light shines upon them. when light strikes the metal the metal emits electrons

planck's theory

energy(light) is emitted or absorbed in discrete units (photon)

atomic spectroscopy

the study of the electromagnetic radiation absorbed and emitted by atoms

emission spectrum

series of bright lines obtained when light emitted by an element is separated into its constituent wavelengths on passage through a prism. (------ for a particular element is always the same and differs from the emission spectra of other elements)

bohr model and emission spectra

each spectral line is obtained when an electron falls from one stable orbit or stationary state to another of lower energy (radiation is absorbed or emitted only when an electron transitions from one stationary state to another)

which electron requires the most energy for emission? why?

the electron that is closest to the nucleus. it is strongly attracted to the protons in the nucleus.

which level is the most stable? what is the name?

n=1 is the most stable. this is called ground state/stable state. any other level is called excited state

what is needed for an electron to change levels?

energy

what happens when an electron jumps to another level

when an electron jumps to another level it stays there for half a second and then it jumps back. this jumping causes a wave to be emitted. the wave length corresponding to the wave emitted is the color.

which level will require minimum amount of energy to move electron? why?

n=5 because it is the farthest away from the nucleus thus having a weaker attraction

what did debrogile demonstrate?

he demonstrated the e- is both particle and wave

de brogile wavelength

a single electron travelling through space has a wave nature; it's wavelength its related to its K.E (energy associated with motion) faster the electron movement, higher is its KE and shorter is its wavelength

what does the wave funtion describe?

-energy of e- with a given wave function
-probabilty of finding e- in volume of space

oribital

a region of probabiltiy where the electron is likely to be found. not a fixed path

principal (n)

refers to the size of the orbital and the energy level of the electron in the orbital

angular momentum or azimuthal (l)

describes the shape of the orbital that an electron occupies

magnetic (m1)

specifies the orientation in space of an orbital

which orbitals have lower energies of binding of the electron to the nucleus (less negative)

higher n orbitals

what happens as n increases

the spacing between levels becomes smaller.

what is the max # of electrons of any orbital?

2 electrons

hunds rule

the most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins

electron configuration

the distribution of electrons of an atom or molecule in atomic or molecular orbitals

ground state

the lowest energy, most stable arrangement

excited state

a higher energy arrangement (it requires energy input)

orbital diagram

pictorial descriptons of the electrons in an atom

auf bau principal

each electron occupies the lowest energy orbital

the pauli exclusion principal

only two electrons can fit into a single orbital

electron spin

the electron can spin in two directions (top spin and bottom spin)

paramagnetic

unpaired electrons generate a magnetic field and are attracted to an external magnetic field.

dimagnetic

paired electrons do not generate a magnetic field and are slightly repelled by an external magnetic field

spontaneous process

process that occurs without ongoing intervention (ie dropping a book in gravitational field)

non spontaneous process

proces that occurs with ongoing outside intervention
(ie extraction of iron metal from iron ore)

which way does a spontaneous reaction move?

a spontaneous reaction will always move towards equilibrium

reaction spontaneity is ____ of the rate of reaction

independant

does a catalyst effect rate of reaction

no

is the reverse reaction spontaneous?

no

does a spontaneous reaction have direction

yes

most spontaneous reactions are __(exo or endothermic?) but some are ______ (eg melting of ice above 0 celcius

exothermic; endothermic

entropy (formal definition)

it is a thermodynamic funtion that increases with the number of energetically equivalent way to arrange the components of a system to achieve a particular state.

entropy (informal definition)

the mesasure of the randomness or disorder of a system, the greater the disorder the greater the entropy

the second law of thermodynamics

for any spontaneous process, the entropy of the universe increases

is entropy a state function or a path funtion?

state function

what is an example of a spontaneous process where entropy decrases?

freezing of water at temperature below 0 degrees

what happens to entropy in an exothermic process

it it increases

what happen to entropy in an endothermic process

it decreases

third law of thermodynamics

the entropy of a perfect crystal at absolute zero, 0k, is zero

energy of activation

energy supplied in a reaction to take the reactant through te transition state

periodic property

property that is predictable based on an elements position within the periodic table

who arranged the periodic table

dimitri mendeleev

henry mosley

discovered the atomic number sequence

valence electrons

electrons in atoms that can participate in the formationof a chemical bond

where are the valence electrons for main group elements

the outermost principal (main)energy level

where are the valence elctrons for transition metals

the ones in the outermost principal (main) energy level ant the outermost d electrons

for most inner transition elements the valence electrons are where?

the ourmost principal (main) energy level and the outermost d and f electrons

elements in the same column have similar chemical properties true or false

true

what do chemical properties depend on?

valence electrons because they are held most loosely

core electrons

electrons in the complete principal energy level and those in the complete d and f sub levels

where is s block

groups 1 and 2

where is p block

groups 13-18

where is d block

groups 3-12

where is f block

lanthanides and actinides

periodic law

the chemical properties of elements are largely determined by the valence electrons they contaon. their properties are periodic because number of valence electrons are periodic

reversible reaction

a reaction that achieves the theoretical limit with respect to free energy

standard free-energy of reaction

the free energy change for a reaction when it occurs under standard state conditions

standard free energy of formation

the free energy change that occurs when 1 mole of the compound is formed from its elements in their standard state

Ionization energy

The minimum Energy (in kj/mol) required to remove an electron atom or ion the gaseous state (always positive because removing an electron always takes energy)

Bond length

The approximate bond length of any two covalently bonded atoms is the sum of their atomic radii

Coulomb's Law

Attraction between a nucleus and an electron increases with increasing magnitude of nuclear charge

Nonbonding atomic radius or van der Waals radius (the radius of an atom when it is not bonded to another atom)

One half the distance between adjacent nuclei in the atomic field

Bonding atomin radius (non metal)

One half the distance between two of the atoms bonded together

Bonding atomic radius or covalent radius (metals)

One half the distance between two of the atoms next to each other in the crystal of the metal

Why atomic radius increases across a period from right to left side?

Because attraction between a nucleus and an electron increases with increasing magnitude of nuclear charge

Nuclear charge

number of protons

Coulombs law

Attraction between a nucleus and an electron increases with increasing magnitude of nuclear charge

why are noble gases the most chemically stable and relatively inert?

the overall energy of electrons occupying the level is low; the elctrons cannot lower their energy by reacting with other atoms or molecules.

why are alkaline metals, alkaline earth metals and halogens extremely reactive?

because they can attain noble gas electron configuration by losing (alkali metals/earth metals) or gaining (halogens) a small number of electrons

effective nuclear charge(average or net charge)

the actual charge minus the charge chielded by other electrons

Atomic radii of d-block elements

Atomic radius increases when moving down the first two rows in a column (group) within the transition elements. Atomic radius for the third row of transition elements is nearly the same as that of the second row due to lanthanoid contraction (outer electrons are held more tightly by the nucleus, offsetting the typical increase in size between periods). With the exception of the first couple of elements in each transition series, atomic radius stays roughly constant across each row (period) because number of electrons in the outermost principal energy level across a row of transition elements is nearly constant (they experience roughly constant Zeff)

cations are _____ than their parent atoms

smaller

anions are ___ than their parent atoms

larger

isoelectronic species

atoms, cations, or anions that have the same number of electrons