atomic number – and atomic mass increase left to right

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SpectRoscopyIdentifying Elements by ColorPeriodic Table: To Date

Atomic Number and Atomic Mass Increase left to rightPeriodic Table: To Date

Electrons in Valence Shell Define Chemical Properties1 e-8 e-4 e-2 e-3 e-Etc.Periodic Table: Today

Electrons in valence orbits Define Chemical PropertiesOrbit 1Orbit 2Orbit 3Orbit 4Orbit 5ElectronsElectrons around an atom can be found in different orbits

Each orbit has its own energy level (compared to the nucleus)Low Energy: Close to the nucleusHigh Energy: Far from nucleus

ElectronsWhen energized, electrons from one energy level to a higher one around the nucleus of the atom.They emit energy in the form of electromagnetic radiation (LIGHT!)If there are an infinite number of electron jumps, a continuous atomic spectrum is created.

Spectral Lines: ColorsLight energy travels in wavesThe wavelength of light determines the color

Emitted Light: MoreShort Waves: HIGH Energy FAR from nucleusLong Waves:LOW Energy CLOSE to nucleus

Spectral Lines: Breaking up LightPrism Breaks up white light into a rainbow of colors (a spectrum)

Diffraction Grating Glass or plastic, ruled with many finely spaced lines (like CD).

Spectral Lines: Emissions from ElementsWhen energy hits an atom, the energy is absorbed by the electrons and they become excited (jump to a higher orbit).When the electrons jump from the higher orbits back to lower orbits, the energy is emitted as light.

Element Identification: Emitted Light

These spectral lines (lines in a spectrum) are unique to each element, so can be used to identify them.Element Identification: Emitted Light

Notice anything about the # of lines in each line spectrum?TOTAL # electrons ?H = 1Li = 3He = 2O = 8C = 6N = 7Element Identification: Emitted Light

Why do they have MORE lines than electrons?H = 1Li = 3He = 2O = 8C = 6N = 7Element Identification: Emitted Light

Why are some lines brighter than others?H = 1Li = 3He = 2O = 8C = 6N = 7LETS EXPLORE!!

a) How does the light that astronomers see from distant stars and galaxies tell them that the same atoms with the same properties exist throughout the universe?

b) Which element is not in the star that produced the unknown spectrum? How can you tell?Atomic Emission Spectrum for Unknown StarEmitted Light: MoreWhen energized, electrons can jump up to higher energy level shellsWhen they move back down they give off some energy as light

Emitted Light: Colors!Different wavelengths make different colors !


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