Electrons Arrangement in the Atom Key words: Energy, wavelength, frequency, photon Use these terms in a sentence (s) which makes sense.

Objectives To use the “Bohr Model for Hydrogen Atom” and “Electromagnetic Spectrum” diagrams from the Reference Tables to relate color, frequency, and wavelength of the light emitted to the energy of the photon. To understand the inverse relationship between wavelength and frequency, and the direct relationship between energy and frequency.

Electrons will give off electromagnetic radiation - When “energized” by heat, electricity, light or chemical reactions. How and why does this happen?

Energy exists in photons A photon has a specific amount (or packet) of energy Also use the word “quantum of energy” Photons with different energy will have specific wavelengths related to the energy

Bohr’s model

Bohr’s Model of the Atom Electrons orbit the nucleus at: At the lowest energy level possible Called the ground state Electrons can be excited by: Electricity, light, chemical reactions When excited, an electron will absorb only a certain amount of energy, A “packet” of energy called a photon or quantum

Bohr’s model

When excited, the electron Will jump to a higher energy level ◦ Called the excited state The electron does not stay in the excited state but falls back toward the nucleus and releases energy

Bohr provided critical information Ground vs. excited state Number of electrons that exist at specific energy levels Bohr’s model works for hydrogen but not for the complex atoms

Emission Spectrum Lab Purpose: To relate the unique emission spectra lines of an element to the energy levels of the atom. Essential Question: What are the emission spectra for specific elements?

This is?

How do neon lights produce the glowing colors? FACTS: Neon is a colorless, inert (non-reactive, non-flammable) gas Neon lights are tubes filled with neon gas.

Neon atoms Normal conditions ◦ Electrons are at the ground state ◦ No light (energy) is emitted Electricity passing through the tube ◦ Atoms absorb energy ◦ Electrons become excited and unstable ◦ Electrons are pulled back toward the nucleus ◦ Electromagnetic radiation is emitted

Elements and their electromagnetic radiation Emissions spectrum Unique for each element Electrons are excited by electricity When they are pulled back by the ____________, they give off __________

Emission Spectrum White light ◦ Write the order of the colors Hydrogen: Nitrogen: Mercury: Neon: Other:

Emission Line Spectra

Emissions Spectra - Simulation charge-lamps charge-lamps Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.

Emission Spectra Unique for each element Used to identify elements as part of unknown compounds

Hubble Space Telescope

Bohr Model Animations for Elements mistry/animations/CHE1.3-an-atoms.shtml mistry/animations/CHE1.3-an-atoms.shtml mistry/animations/CHE1.3-an-atoms.shtml mistry/animations/CHE1.3-an-atoms.shtml