Do Now Welcome Back! HMSA: we have 1st lunch! Take out Atoms/Nuclear packet from last week to get checked Today: Energy, Waves Next week: flame test lab 

What do these 6 items all have in common?

Electromagnetic radiation - a form of energy that has wavelike properties - all forms found in the electromagnetic spectrum Examples of electromagnetic radiation: Xrays Microwaves Light waves Radio waves – when you hear static on the radio when you aren’t getting a signal, that is the leftover microwaves from the big bang 15 billion years ago (it is cooling off so now the waves are the energy and wavelength of radio waves)

ELECTROMAGNETIC RADIATION RADIO WAVES MICRO- WAVES INFRARED LIGHT VISIBLE LIGHT UV LIGHT X-RAYS LOWEST ENERGY HIGHEST ENERGY

Listening to music in the car using the radio RADIO WAVES Listening to music in the car using the radio

MICROWAVES Making popcorn

Using the remote control INFRARED LIGHT Using the remote control

The blue color of the sky VISIBLE LIGHT The blue color of the sky

ULTRAVIOLET LIGHT Using a tanning booth

X-RAYS Checking to see if the ankle was broken

Examples of Waves All EMR waves move following a specific pattern, but the energies and characteristics associated with the waves can vary

Determining Characteristics of a Wave Use string to make waves Try your best to estimate the measurements Assume the length of 1 tile is 1 foot

Photons - released during electromagnetic radiation – tiny particles that have no resting mass which carry a quantum of energy All photons travel at the speed of light in a vacuum

Photons behave as particles quantum – the minimum amount of energy that can be absorbed or released from an atom - cannot be any value but are in discrete energy levels (like bundles or packets of energy) quantized = certain energy levels, not all can be reached (like monkey bars, you can’t grab a bar that is in between, it’s not possible)

𝑐=𝑣λ 3.00× 10 8 =𝑣×4.9× 10 −7 𝒗=𝟔.𝟏× 𝟏𝟎 𝟏𝟒 𝑯𝒛

3.17 m 1.70 x 10-22 J 8.28 x 10-16 J 1.0 x 10-5 m

Electrons and Energy Levels Each electron has a distinct amount of energy that is related to the energy level (shell) it is in Electrons with the lowest energy are found in the shell closest to the nucleus Electrons with the highest energy are found in the shell furthest from the nucleus The greater the distance from the nucleus, the greater the energy of the electron

Each energy level has a maximum number of electrons that it can hold The smallest energy level (the one closest to the nucleus, the first) can hold 2 electrons. The second energy level, can accommodate 8 electrons. The third energy level, can accommodate 18 electrons. The 4th energy level can accommodate 32 electrons N e 1 2 2 8 3 18 4 32

HOW DOES A NEON SIGN WORK? BECAUSE OF ELECTRONS

Ground vs. Excited State Ground state=when the electrons occupy the lowest energy levels possible Excited state=electrons are found in a higher energy level or shell (even when a lower energy levels is not completely full)

Ground and Excited State When an electron gains energy, it jumps to a higher energy level or shell This is a very unstable condition We call this condition the excited state Very rapidly, an electron in the excited state will lose energy and move back to a lower energy level or shell When excited electrons fall from an excited state to a lower energy level, they release energy in the form of light

Ground  Excited State Electron gains energy from heat, light, electricity Electron “jumped” to a higher energy level (shell)

Excited  Ground State Electron releases energy in the form of light Electron “falls” back and returns to ground state (normal position)

Ground and Excited State Summary Ground State  Excited State Energy is absorbed (gained) Excited state is produced Excited State  Ground State Energy is released (in the form of light) Ground state is produced

Bright Line Spectrum Electrons falling from an excited state down to the ground state give off visible light Different elements produce different colors of light or spectra These spectra are unique for each element (just like a human fingerprint is unique to each person)

Demo