Bell Work AgendaNotes: Atomic Spectrum

Flame Test demo

Bohr Model Practice

• What is the difference between a conceptual and a physical model?

• What scientists have a conceptual model? A physical model?

Atomic SpectrumMarch 27, 2013

Objectives1. Explain why scientists know the identity of

the chemical compositions of stars2. Describe a flame test3. Describe the Bohr model in terms of

energy

Atoms can absorb and release energy

When atoms release energy they emit light

Each atom emits only a certain frequency of light

When electrons absorb energy they get excited and jump around

When jump back to the original position they release that energy as light

Flame Test Na Li B Cu Ca

Quantum hypothesis beam of light is both wave and stream of

particles – photons

Spectroscope White light separates into its color

components by a prism

Each color corresponds to a different frequency of electromagnetic radiation

Spectroscope Observe color components of any light

source

Atomic Spectrum Light from atoms consist of a number of

individual frequencies rather than a continuous spectrum

Pattern of frequencies of a particular element – atomic spectrum

Atomic spectrum – atoms “finger print”

Shell model A region of space around the atomic

nucleus where electrons may be

Each shell can hold a limited amount of electrons

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

Valence Electrons Electrons in the outermost shell “combining

power”

Directly exposed to the external environment

The first to interact with other atoms