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Chapter 11 Modern Atomic Theory. This chapter helps us understand why chemicals do the things they do!!. What are atoms like? What is the structure of one? We learned a little about them earlier, and how they were grouped (on the Periodic Table)
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Chapter 11Modern Atomic Theory This chapter helps us understand why chemicals do the things they do!!
What are atoms like? • What is the structure of one? • We learned a little about them earlier, and how they were grouped (on the Periodic Table) • It has everything to do with electrons and how they are arranged • But first! electromagnetic radiation…
11.1 rutherford’s atom • Remember: Rutherfordand his buddies (in Ch 3) found that the atom had a nucleus with electrons on the outside • The nucleus was very small and was made of p and n • The e- made up the rest of the atom…
But what were the e- doing?How were they arranged?Why didn’t they just crash into the nucleus? • Somethingmore wasneeded!!! • We needenlightenment!
11.2 energy and light • When Energy is transmitted from one place to another by light we call it Electromagnetic radiation • Examples include lightbulbs, fire places, the sun, X-rays, microwave ovens, you! • But what’s the difference between all these light sources ?
It has to do with waves and their properties • Waves have three main characteristics: Wavelength, Frequency, & Speed…
Wavelength (l) is the distance between two consecutive wave peaks • Frequency (n) is how many waves pass a given point per given time • speed is, obviously, how fast a wave travels through its “medium” • Light does asimilar thing towater waves; ittravels at lightspeed with land n…
The ELECTROMAGNETIC SPECTRUM!! a.k.a. EM
The EM radiation mentioned earlier all have their l and n, and all transfer Energy from one place to another - even through space! • What’s extra weird about light, though, is that it can behave as waves and as particles at the same time!!!…
The light “particles” are called photons • So is it a wave or a particle? both!!! • Called wave-particle nature of light
Different wavelengths carry different amounts of energy, blue more than yellow more than red… • X-rays more than uv, visible more than IR, IR more than radio, etc.
11.3 Emission of energy by atoms • Why the different colors here?
they only light up when they receive energy (from the flame or electricity); but why??? • perhaps the atoms are getting excited by absorbing the E • when they release that same amount of E they give off in the form of light
here Li is giving off a photon of reddish light; Cu would give off green, sodium yellow • but, again, why? • somehow they give off the exact amount of E they received and are happier b/c of it