Class 1 Flashcards
Isotopes
have the same atomic number but different mass number
Atomic weight of an element
is a weighted average
emission spectrum
separate the light into its component wavelengths
What does an atom’s emission spectrum indicate?
An atoms emission spectrum gives an energetic “fingerprint” of that element because it consists of a unique sequence of bright lines that correspond to specific wavelength and energies
E=
E = hf = h c/lambda
E———energy
lambda ——– wavelength
h
it is a universal constant called Planck’s constant
h =
6.63 x 10^-34 J.s
c
speed of light
Bohr model of the atom
he proposed that electrons in an atom orbited the nucleus in circular paths, like the planets orbit the sun
What happens when an electron absorbs energy
it jumps from the current level to the higher energy level.
What happens when an electron drops to a lower energy level?
it emits a photon with an energy exactly equal to the difference between the levels
What does the bohr model predict?
it predicts that elements would have line spectra instead of continuous spectra.
since only photons with certain energies are observed. These specific energies correspond to very specific wavelengths, as seen in the emission line spectra.
higher energy level is known as an
excited state
Two possible ways the electron can lose energy -
hf= E2-E3
hf=E1-E3
E3 = higher energy state
E1- lower energy state
How to calculate energy differences between discrete levels?
by subtracting the initial energy of the electron from the final energy of the electron
