1. Atomic Spectrum
March 11, 2015

2. Objectives
1. Explain why scientists know the identity of
the chemical compositions of stars
2. Describe a flame test
3. Describe the Bohr model in terms of
energy

3.  Atoms can absorb and release energy
 When atoms release energy they emit light
 Each atom emits only a certain frequency
of light

4. Shell(Bohr) model
 A region of space around the atomic
nucleus where electrons may be
 Each shell can hold a limited amount of
electrons

5.  Series of seven shells accounts for the
seven periods
 Number of electrons held in each period is
equal to the shell’s capacity for electrons

7. Valence Electrons
 Electrons in the outermost shell “combining
power”
 Directly exposed to the external
environment
 The first to interact with other atoms

8.  When electrons absorb energy they get
excited and jump around
 When jump back to the original position
they release that energy as light

9. Flame Test
Na Li B Cu Ca

10. Spectroscope
 Observe color components of any light
source

12. Atomic Spectrum
 Light from atoms consist of a
number of individual
frequencies
 Pattern of frequencies of a
particular element – atomic
spectrum

13.  White light separates into its color
components by a prism
 Each color corresponds to a different
frequency of electromagnetic radiation

14.  Atomic spectrum – atoms “finger print”
 Emission – the frequencies the gas emitts
 Absorption – frequencies of all white light
EXCEPT those that are absorbed by the
gas

16. •
 Emission
 Absorption

17.  http://jersey.uoregon.edu/vlab/elements/Elemen