Light and Atomic Spectra

electromagnetic radiation

energy that exhibits wave-like behavior as it travels through space
radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays
-differences in frequency and wavelength

wavelength, frequency, amplitude

what are the 3 characteristics of waves

wavelength

shortest distance between equivalent points on continuous wave
(λ)
-bigger wavelength=low energy; smaller energy=high energy
-crest to crest; trough to trough
-measured in m, nm, cm

frequency

number of waves to pass a given point per second
(ν)
-higher frequency=small wavelength; lower frequency=large wavelength
-hertz=(1 wave/second)=waves/sec=s^-1

amplitude

waves height from origin to crest

c=λν

speed of light equation
-in this equation, frequency and wavelength are inversely related

3.00 x 10^8m/s

what does c = in the speed of light equation

particle nature of light

light as a wave describes most behaviors
metals emit electrons when light of specific frequency shines on them
when metals get hot emit different energy; seen as different wavelengths of light
Max Planck stated matter can gain/lose energy in small specific amounts called quanta
-quantum
explained mathematically that the amounts of radiant energy (E) absorbed or emitted by a body is proportional to the frequency of the radiation
E= hν
h=constant; Planck's constant = 6.626 x 1-^-34 J x s
-size of emitted/absorbed quantum depends of size of energy change
-relationship exists between energy of quantum and frequency of emitted radiation
-only emit/absorb energy in whole number multiples of hν

quantum

minimum amount of energy that can be gained or lost by an atom

E=hν

equation for energy

6.626 x 10^-34 J x s

what does h stand for in energy equation

photoelectric effect

electrons (photoelectrons) are emitted from a metal's surface when light of certain frequencies shine on them
metals won't eject photoelectrons below specific frequency
frequency (energy) of light increase; electrons travel faster
increase the intensity of light, increase number of electrons ejected

albert einstein

proposed light has dual nature
-beam of light has wave-like and particle-like properties
-beam of bundles energy- photon - massless particle that carries quantum of energy
-energy of photon depends on frequency

photon

massless particle that carries quantum of energy

dual nature

every element emits light when it is excited by passage of an electric discharge thru its gas or vapor
atoms absorb light (energy) 1st becomes excited; return to stable state by emitting light to release energy
atomic emission spectrum

atomic emission spectrum

set of frequencies of electromagnetic waves emitted by atoms of an element
- passing lights emitted by an element thru a prism
- emission spectrum unique to that element/used to identify the element
-only certain colors appear which means only specific frequencies of light are emitted
-only photon with specific energy emitted
- absorb same frequency as emit

neils bohr

1913
discovered that electrons have certain allowable energy states
ground state
excited state
electrons moved in circular orbits
smaller orbit, lower energy; larger orbit, higher energy
quantum
energy level

ground state

lowest allowable energy state of atom

excited state

when atoms gain energy

quantum

(n) each orbit's number, also calculated radius
-n= 1, 2, 3, ect

energy level

a region around nucleus where electrons are likely to be moving
-at ground state; atom does not radiate energy
-energy from outside source added; electrons moves to higher energy level
-when atom in excited state; electrons can drop to lower energy orbit
-emit photon corresponding to energy difference between 2 levels
-can only move from 1 allowable orbit to another
-only emit/absorb certain amounts of energy
-orbits not equally spaced

quantum mechanics

matter has wave and particle characteristics
louis de broglie's equation predicts all moving particles have wave characteristics
easy to calculate wavelength of moving electron
wavelengths of objects visible to the unaided eye are too small to measure
if electron has wave-like motion and restricted to circular otbits of fixed radius, only certain wavelengths, frequencies, and energies are possible
λ=h/m(v)
h=Plancks constant
m= mass of the particle
v= velocity

Heisenberg uncertainty principle

impossible to take any measurement of an object without disturbing it
act of observing an electron produces significant, unavoidable uncertainty in the position and motion of the electrons
it is impossible to know exactly both the velocity and position of a particle at the same time
this principle means that it is impossible to assign fixed path for electrons
only quantity known: probability that an electron occupies a region around the nucleus

quantum mechanical model

physicist erwin schrodinger atomic model where electrons are treated as waves
limits an electron's energy to certain values
no attempt to describe electron's path
estimates probability of finding electron in a particular volume around nucleus
atomic orbital

atomic orbital

electron probable location
-fuzzy cloud; density proportional to probability of finding electrons
-not exact, defined size

atomic orbital

principle quantum number (n)- assign quantum numbers to atomic orbitals
-indicates relative size and energy of orbital
- "n" increases; electrons spends more time farther from nucleus with atom's energy increase
- each number refers to major (principle) energy level

energy sublevels

within principle energy levels
number of sublevels increase with increase energy levels
number of sublevels same as major (principle) energy levels

shapes of orbitals

sublevels are labeled s, p, d, f, because of shape of orbital
"s"=spherical (1)
"p"=dumbbell shaped, 3 kinds have different orientations in space (x, y, z)
"d" and "f"= not all same shape d(5); f(7)
number and kinds of atomic orbitals depend on energy sublevels
maximum number of orbitals related to each principle energy level is n^2
maximum number of electrons that can occupy a principle energy level = 2n^2 (n=principle energy level)
every orbital can only hold 2 electrons

electron configurations

arrangement of electrons in an atom
electron assume arrangements with the lowest possible energy = ground state electron configuration
there are 3 rules you must follow

aufbau principle

electrons occupy orbitals of lowest energy first
all orbitals related to an energy sublevel are of equal energy
-ex: all three 2p orbitals are equal
energy sublevels within principle energy level have different energies and increase energy (3s, 3p, 3d have different energies)
range of energy levels within a principle level can overlap energy levels of an adjacent principle level
*make sure you know how to draw the chart

pauli exclusion principle

electron orbital represented by arrows in boxes
max of 2 electrons can occupy a single atomic orbital but only if electrons have opposite spin

hund's rule

single electron with same spin must occupy each equal energy orbital before additional electron with opposite spins can occupy same orbitals

electron arrangement

represented by orbital diagrams or electron configuration notation

orbital diagrams

a.k.a. boxes and arrows
boxes labeled with principle quantum number and sublevel
arrows to represent electrons

electron configuration notation

principle energy level/sublevel with superscript of number electrons
doesn't show orbital distributions

noble gas notation

have 8 electron outermost orbital/very stable
use bracketed symbols [He]=1s^2
shortened way to represent
use noble gas in previous row and electron configuration notation to fill additional orbitals

exceptions

more stability with half-fillled and filled sets of "s" and "d" orbitals
Cr=[Ar]4s^2 3d^4 --> [Ar]4s^1 3d^5
Cu=[Ar]4s^2 3d^9 --> [Ar]4s^1 3d^10

valence electrons

in atom's outermost orbitals (highest principle energy level)
determine chemical properties

electron dot structure

visual shorthand method to represent electrons
symbol (nucleus/inner electron) and dots (valence electrons)
start 1 side on a side until all sides have 1/ then pair up

numbers; distance/energy

how is the principle energy level represented and what does it tell us

letters; shape

how is the number of sublevels represented and what does it tell us

c

the electrons in an atom's outermost orbitals are called
a. electron dots
b. quantum electrons
c. valence electrons
d. noble-gas electrons

b

in an electron-dot structure, the element's symbol represents the
a. nucleus of the noble gas closest to the atom in the periodic table
b. atom's nucleus and inner-level electrons
c. atom's valence electrons
d. electrons of the noble gas closest to the atom in the periodic table

d

how many valence electrons does a chlorine atom have if its electron configuration is [Ne]3s^2 3p^5?
a. 3
b. 21
c. 5
d. 7

a

which electrons are represented by the dots in an electron-dot structure?
a. valence electrons
b. inner-level electrons
c. only s electrons
d. both a and c

orbitals

n^2 represents the maximum number of _________ in an energy level

electrons

2n^2 represents the maximum number of _________ in an energy level

c

as the frequency of light increases, the wavelength
a. increases
b. remains the same
c. decreases
d. approaches the speed of light

c

bohr's contribution to the development of atomic structure:
a. was referred to as the "plum pudding model"
b. was the discovery that electrons surround a dense nucleus
c. was proposed that electrons travel in circular orbits around the nucleus
d. is the quantum mechanical number

c

which of the following can you conclude based on the de Broglie equation?
a. waves behave like particles
b. most particles are electrons
c. all matter has an associated wavelength
d. all matter behaves like particles

a

emission of light from an atom occurs when the electrons
a. drops from a higher to a lower energy level
b. jumps from a lower to a higher energy level
c. moves within its atomic orbital
d. fall into the nucleus

a

the atomic emission spectra of a sodium atom on earth and of a sodium atom in the sun would be
a. the same
b. the same as those of other elements
c. different from each other
d. the same as each only in the UV range

c

the quanta of light are called:
a. charms
b. muons
c. photons
d. excitons

c

which of the following best describes the Heisenberg uncertainty principle?
a. light behaves like a particle and like a wave
b. the shorter the wavelength; the higher the frequency
c. it is impossible to know both the velocity and position of a particle at the same time
d. you can measure an object without disturbing it

quantum mechanical model of the atom

the modern model of the atom that treats electrons as waves

heisenberg uncertainty principle

states that it is impossible to know both the velocity and the position of a particle at the same time

atomic orbital

a three-dimensional region around the nucleus representing the probability of finding an electron

schrodinger wave equation

originally applied to the hydrogen atom, it led to the quantum mechanical model of the atom

do not

atomic orbitals (do, do not) have an exactly defined size

two

each orbital may contain at most (two, four) electrons

spherically

all s orbitals are (spherically, dumbbell) shaped

n

a principle energy has (n, n^2) energy sublevels

electrons

the maximum number of (electrons, orbitals) related to each principal energy level equals 2n^2

three

there are (three, five) equal energy p orbitals

2s and 2p

hydrogen's principal energy level 2 consists of (2s and 3s, 2s and 2p) orbitals

nine

hydrogen's principal energy level 3 consists of (nine, three) orbitals

b

the frequency and wavelength of all waves are:
a. directly related
b. inversely related
c. unrelated
d. equal

c

the SI unit of cycles per second is called a(n)
a. photon
b. quantum
c. hertz
d. meter

b

once the electron in a hydrogen atom absorbs a quantum of energy, it:
a. is now in its ground state
b. is now in its excited state
c. has released a photon
d. none of these

b

which of the following electromagnetic waves have the highest frequency?
a. uv waves
b. gamma rays
c. x-rays
d. microwaves

c

which color of the visible light has the shortest wavelength?
a. orange
b. green
c. violet
d. yellow

b

the quanta of light are called
a. charms
b. photons
c. excitons
d. muons

energy, wave, light, speed, wavelength, amplitude, frequency, hertz

electromagnetic radiation is a kind of _______ that behaves like a(n) ______ as it travels through space. ________ is one type of electromagnetic radiation. Other examples include x-rays, radio waves, and microwaves. All waves can be characterized by their wavelength, amplitude, frequency, and ________. The shortest distance between equivalent points in a continuous wave is called a(n) __________. The height of a wave from the origin to a crest or from the origin to a trough is the ___________. ________ is the number of waves that pass a given point in one second. The SI unit for frequency is the ______, which is equivalent to one wave per second.
Word Bank: amplitude, energy, frequency, hertz, light, wave, wavelength, speed

c

a(n) __________ is the minimum amount of energy that can be lost or gained by an atom.
a. valence electrons
b. electron
c. quantum
d. planck's constant

b

according to planck's theory, for a given frequency, v, matter can emit or absorb energy only in
a. units of hertz
b. whole-number multiples of hv
c. entire wavelengths
d. multiples of 1/2hv, 1/4hv, and so on

d

the __________ is the phenomenon in which electrons are emitted from a metal's surface when light of a certain frequency shines on it.
a. quantum
b. planck concept
c. photon effect
d. photoelectric effect

b

which equation would you use to calculate the energy of a photon?
a. Ephoton=hv X Planck's constant
b. Ephoton=hv
c. Ephoton=1/2hv
d. c=λv

false

T or F: like the visible spectrum, an atomic emission spectrum is a continuous range of colors

true

T or F: each element has a unique atomic emission spectrum

true

T or F: a flame test can be used to identify the presence of certain elements in a compound

true

T or F: the fact that only certain colors appear in an element's atomic emission spectrum indicated that only certain frequencies of light are emitted

false

T or F: atomic emission spectra can be explained by the wave model of light

false

T or F: the neon atoms in a neon sign emit their characteristic color of light as they absorb energy

true

T or F: when an atom emits light, photons having certain specific energies are being emitted

d

how many f orbitals can there be in one atom?
a. 1
b. 3
c. 5
d. 7
e. 9

d

what is the maximum number of d orbitals in a principle energy level?
a. 1
b. 2
c. 3
d. 5
e. 10

b

what is the maximum number of orbitals in the p level?
a. 2
b. 3
c. 4
d. 5
e. 6

b

what is the maximum number of electrons in the second principle energy level?
a. 2
b. 8
c. 18
d. 32

b

the formula 2n^2 represents_________
a. the number of orbitals in a sublevel
b. the maximum number of electrons that can occupy an energy level
c. the number of sublevels in any energy level
d. none of the above

d

which of the following states that no more than 2 electrons can occupy an atomical orbital and that two electrons in the same orbital must have opposite spins?
a. hund's rule
b. dalton's theory
c. the aufbau principle
d. the pauli exclusion principle

d

in order to occupy the same orbital, two electrons must have ___________
a. the same direction of spin
b. low energy
c. a high quantum number
d. opposite spin

d

according to the aufbau principle__________
a. an orbital may be occupied by only two electrons
b. electrons in the same orbital must have opposite signs
c. electrons enter orbitals of highest energy first
d. electrons enter orbitals of lowest energy first

b

the letter "p" in the symbol 4p^3 indicates the
a. spin of an electron
b. orbital shape
c. principle energy level
d. speed of an electron

b

the 3p atomic orbital has the shape of ________
a. a sphere
b. a dumbbell
c. a bar
d. two perpendicular dumbbels
e. an egg

b

how many energy sublevels are there in the second principle energy level?
a. 1
b. 2
c. 3
d. 4
e. 5

c

what types of atomic orbitals are in the third principle energy level?
a. s and p only
b. p and d only
c. s, p, and d only
d. p, d, and f only
e. s, p, d, and f

d

the quanta of light are called _______
a. charms
b. excitons
c. muons
d. photons
e. solitons

7

how many f orbitals can there be in atom?

8

what is the maximum number of electrons in the second principle energy level?

orbital shape

what does the letter "p" in the symbol 4p^3 represent?