Ch.11 Modern Atomic Theory Flashcards
Dalton’s Atom
indivisible particle with no internal parts
Thomson’s atom
Plum pudding model
Rutherford’s atom
nuclear model of an atom
the atom has a small dense nucleus that contains?
positively charged
contains proton(+1 charge)
contains neutrons (no charge)
the remainder of an atom contains?
mostly space
contains electrons (1- charge)
how is the nuclear charge (n+) balanced by?
the presence of n electrons ( n- n-charge) moving around the nucleus.
the greatest wavelength to smallest wavelength
- Radio waves (FM/Shortwave/AM)
650-700 nm - Microwaves
600nm - Infrared
550 nm - Ultraviolet
500 nm - X-rays
450 nm - Gamma rays
400 nm
what is the electromagnetic wave composed of according to Maxwell?
oscillating electric and magnetic fields
define wavelength:
horizontal distance in space between two adjacent crests or two adjacent troughs ( or any two analogous points)
define amplitude:
vertical height of a crest or depth of through ( indicates the strength of its electric and magnetic fields)
define frequency(v):
the number of cycles (or wave crests) per second that pass through a given point in space
define speed(c):
the product of wavelength and frequency, a constant that defines the EM wave velocity (distance per sec)
what is the frequency directly proportional to?
directly proportional to the speed at which the wave is traveling
ex: the faster the wave the more crests pass a fixed location per unit of time
what is frequency inversely proportional to?
the wavelength
ex: the farther apart the crests the fewer that pass a fixed location per unit of time
what did Einstein think of light?
believed that light is a collection of discrete packets of energy
each packet contains an amount of energy E that is directly determined by its frequency
what is a packet of light called?
photon or quantum of light
what is the plank’s constant value?
h=6.626 x 10 ^34 j*s
the energy of a photon can also be expressed in
terms of wavelengths
the energy of a photon is directly proportional to what?
its frequency
Ex: the higher the frequency, the greater the energy
the energy of a photon is indirectly proportional to what?
its wavelength
Ex: the longer the wavelength, the smaller the energy
A bright source of light emits?
a dense stream of photons
A dim source of light emits?
relatively few photons
how do atoms emit light?
by first receiving energy and becoming excited
the energy is released in the form of a photon
the energy of the photon corresponds exactly to the energy change experienced by the emitting atom
when is the atom with excess energy?
excited state
when is the atom in the lowest possible state?
ground state
what is line spectrum?
a series of light emission at different wavelengths
quantization of energy
Energy levels where only certain values are allowed
the energy levels of all atoms are?
quantized
how is the energy of electrons described?
orbitals
Chemists define an orbital size as the?
90% probability contour
the electron is somewhere within that volume 90% of the time
hydrogen has discrete energy levels called
principal energy levels
the higher the n value
the higher the energy level
as the principal level number n increases……..
the size of the orbital increases
the electron is at a higher energy level
the electron is farther from the nucleus on average
the electron spends more time farther from the nucleus
why was the Bohr model disregarded?
bc it does not apply to all atoms
electron spin is a
fundamental property of an electron
- all electrons have the same amount of spin
- the orientation of the electron’s spin is quantized w/ two possible values +1/2 and -1/2
Pauli exclusion principle
an atomic orbital holds a maximum of two electrons and those two electrons must have opposite spins
Hund’s rule
if more than one orbital in a sublevel is available add elections with parallel spins to different orbitals of that sublevel
electron configuration
describes the distribution of electrons among the various orbitals in the atom
what does the spdf notation use?
numbers (n) to designate a principal level (or shell)
letters (l) to identify a sublevel (or subshell)
a superscript number (#) indicates the number of electrons in the designated subshell
orbital diagram
orbital is a box grouped by sublevel (subshell) containing arrow(s) to represent electrons
rules for writing electron configurations
- determine the # of electrons to appear in the electron configuration
- add electrons to the subshell in order of increasing subshell energy
- observe the Pauli exclusion principle
- observe Hund’s rule
define core electrons
electrons in inner energy levels
define valence electrons
electrons in the outermost (highest) principal energy level (shell) of an atom
periodic properties examples
melting point
boiling point
hardness
density
physical state
chemical reactivity
metals have
small number of electrons in their valence shells and tend to form positive ions
cations form
when the atoms of an element lose electrons to attain a complete valance shell
nonmetals generally
have larger numbers of electrons in their valance shell than do metals and tend to form negative ions
Anions formed
when the atoms of an element gain electrons to attain a complete valance shell
