Aim: How to distinguish electrons in the excited state DO NOW: PREPARE FOR QUIZ. 10 MIN

What gives gas-filled lights their colors?  An electric current passing through the gas in each glass tube makes the gas glow with its own characteristic color.

The Nature of Light  Light is a part of the electromagnetic spectrum-radiant energy composed of gamma rays, X-rays, ultraviolet light, visible light, etc.  The energy of the electromagnetic spectrum moves through space as waves

Nature of Light  Sunlight consists of light with a continuous range of wavelengths and frequencies.  When sunlight passes through a prism, the different frequencies separate into a spectrum of colors.  In the visible spectrum, red light has the longest wavelength and the lowest frequency.

Atomic Spectra  When atoms absorb energy, their electrons move to higher energy levels. These electrons lose energy by emitting light when they return to lower energy levels.  The excitation fallback theory explains the visible emission (bright line) spectrum of element  A ground state for the electrons in an atom is an energy state of lowest energy  An excited state is an energy state of higher energy

 In order for an electron to go from its ground state to an excited state, it must absorb a certain amount of energy. If the electron dropped back from that excited state to its ground state, that same amount of energy is emitted.

Emission Spectrum  A prism separates light into the colors it contains. White light produces a rainbow of colors.

Emission Spectrum  Light from a helium lamp produces discrete lines. Excited hydrogen atoms emit a pinkish glow. When the visible portion of the emitted light is passed through a prism, it is separated into specific wavelengths that are part of the hydrogen’s line emission spectrum.

Emission Spectrum  The wavelengths of the spectral lines are characteristic of the element, and they make up the atomic emission spectrum of the element.  No two elements have the same emission spectrum.  The fingerprints of an element.

Energy of Light  Light can be described as a quanta, or packet, of energy that behaves as if they were particles. Light quanta are called photons. The energy associated with a certain frequency of light is related by the equation:  h = 6.63 X Js

U DO IT NOW! For the following configuration: a) Identify the element. b) Propose an excited state. Simply add the electrons, which equal protons in a neutral atom, the atomic number : = 34 electrons indicates an atomic number of 34, which is Se Write a configuration with the same number of electrons as the ground state, but with a different configuration (ground): (excited) ♫NOTE – electrons furthest from the nucleus are most likely to be excited (promoted).