Flame Tests Pick up a notes sheet!

Energy of a wave Low frequency = long wavelength = low energy High frequency = short wavelength = high energy

Energy and color Which colors of light are high energy? Which colors of light are low energy?

Energy and color Which colors of light are high energy? (high) violet, blue, the green (middle) UV is even higher energy

Energy and color Which colors of light are low energy? Yellow, orange, red (low) infrared is even lower energy

Back to the Electron World Electrons of an atom can have different energy levels (and be different distances from the nucleus) Electrons closest to the nucleus have the lowest energy and electrons farther away have more energy. It’s similar to gravity in that the farther up you are the more potential energy you have (only this is electric potential not gravitational potential energy)

Back to the Electron World Electrons are usually in their ground state (low energy, stable state). This means they are all as close to the nucleus as possible (so 2 in the first shell, up to 8 in the 2nd shell, etc. but NONE in higher shells unless all the lower ones are full) If electrons gain energy, they JUMP up to a higher energy level and are in their excited state.

How do flame tests work? Step one: when an electron absorbs energy (like heat! Or electricity!) it jumps to a higher energy shell – this is unstable! Example: The electron in a hydrogen atom jumps from shell 1 to shell 4. e-

How do flame tests work? Step two: eventually the electron will go back down to the more stable energy level and in the process it will release a photon of light (some of these downward jumps give off visible light!) Why do they give off light? Because they have to get rid of the “extra” energy they had in the excited state. Light is energy! e- photon of light

Why the different colors? Depending on the energy of the jump (which levels jumped to and from) different wavelengths of light will be given off. Different wavelength = different energy = different color! Because every element has different chemical properties (because of electron locations), the flame color will be different!

Big jump = high energy What color of light will be emitted?

Big jump = high energy What color of light will be emitted? Violet, blue (high energy) Even bigger jumps mean ultraviolet

Small jump= low energy What color of light will be emitted?

Small jump= low energy What color of light will be emitted? Red, orange Really small jumps give off infrared light Medium jumps give off yellow or green light

Final question: If a valence electron in calcium jumps from the 4th shell to the 6th shell, do we still have calcium?

Final question: If a valence electron in calcium jumps from the 4th shell to the 6th shell, do we still have calcium? YES! The only way to change the identity of an element is to change the number of protons!

Ok now for the lab SAFETY! Wear goggles! Tie back long hair! Mr. C will show you how to light a Bunsen burner and how to make colored fire! Your task: gather the data and answer the lab questions. (no write up  )