Slide 1 / 141 Slide 2 / 141 Chemistry Atomic Origins 2015-10-27 www.njctl.org Slide 3 / 141 Slide 4 / 141 Table of Contents: Creation of Matter Click on the topic to go to that section · The Big Bang The Big Bang · Electrons & Protons · The Nucleus · Formation of the Elements · Isotopes · Radioactive Decay · Half-Life Return to Table of Contents Slide 5 / 141 Slide 6 / 141 Chemical Elements Chemistry Scientists have discovered all of the matter in our Universe is made up of 116 different types of chemical elements. The observable Universe is made up of amazing stuff. We more formally About 90 of these elements occur naturally. call this stuff matter. Humans have always been curious about the nature of matter: where did matter come from? what is it made out of? why does it behave the way it does? http://www.periodictable.com/
Slide 7 / 141 Slide 8 / 141 The Beginning... The Beginning... Where did the elements that makes up the Universe come from? You were correct if you said the prevailing theory is that the Universe began with the "Big Bang," which is an event thought to have occurred about 14 billion years ago. Slide 9 / 141 Slide 10 / 141 Big Bang Theory Big Bang Theory It is believed our Universe began at a single point. This one spot was thousands of times smaller than the head of a pin. It was also hotter and more dense than any object we know of today. This heat still remains as Cosmic Background Radiation. This Universe began expanding suddenly and rapidly from this single point. Consequently, every piece of matter, all the "stuff" in the universe came from this small, dense spot! Slide 11 / 141 Slide 12 / 141 Energy and Matter 1 Scientists believe the Big Bang happened: 14 billion years ago, in the flash of the Big Bang high energy A 14 million years ago photons (light particles) collided with each other, forming oppositely charged particles. Typically, when this happened the oppositely charged matter and antimatter annihilated B 14 trillion years ago each other instantly, converting back into high energy photons. C 14 billion years ago D within the last 3000 years Photons Photons Oppositely Charged Matter Charged Antimatter
Slide 13 / 141 Slide 14 / 141 Energy and Matter Cosmic Background Radiation 2 Students type their answers here In the first seconds of the Universe, for reasons "As the universe expanded, both the plasma and the radiation filling scientists cannot explain, it is estimated that one it grew cooler. When the universe cooled and stable atoms could particle of matter for approximately every one billion form, they eventually could no longer absorb the thermal radiation and the universe became transparent instead of being an opaque particles of antimatter were not annihilated. (You fog. The photons that from that time have been propagating ever could win a Nobel Prize if you figure out why!) since, growing fainter and less energetic." In this environment three major particles formed: + positively charged particles neutrally charged particles - negatively charged particles What are these positive, negative and neutral particles called? What is the magnitude of their charge? What are their masses? http://www.universetoday.com/79777/cosmic-background-radiation/ Slide 15 / 141 Slide 16 / 141 Formation of the Elements 3 Following the Big Bang, the universe: 3 minutes after the Big Bang, the Universe began to cool A expanded and then rapidly stopped expanding. down from (1x 10 32 °C to 1 x 10 9 °C) and protons and neutrons began to combine. B expanded and has not stopped expanding since. C rapidly expanded and then shrunk back to its original size. + + Slide 17 / 141 Slide 18 / 141 Formation of the Elements Stellar Furnaces About 300,000 years later, the universe had cooled enough During the formation of the universe only atoms of the lightest for positively charged protons to attract the negatively elements - hydrogen, helium, lithium and beryllium were formed. charged electrons, and the first atoms were formed. As the cloud of cosmic dust and gases from the Big Bang cooled, - - - stars formed, and these then grouped together to form galaxies + + and stars. + The high pressure and temperature within Stars caused protons and neutrons to fuse together. Hydrogen-2 Hydrogen-1 Hydrogen-3 Deuterium Tritium In smaller stars like our Sun, the temperatures are 15.5 million C at the - - - core, hot enough to make Helium from - - + + + 3 4 Hydrogen only. + 4 5 - - - - Helium-4 Lithium-7 Beryllium-9
Slide 19 / 141 Slide 20 / 141 Larger Elements Formation of Heavier Elements In the core of hotter, larger giant stars: Atoms of elements The most massive elements hydrogens fuse to make helium from iron to uranium were aluminum to iron formed in Sun created in star explosions Super Giant stars. heliums fuse to make atoms called supernovae. 26 with 4 protons - beryllium . - + helium and beryllium fuse to 26 Red Giant Red Supergiant make atoms with 6 protons - 30 carbon carbon and helium fuse to make Blue atoms with 8 protons - oxygen, Giant etc., and in this manner Blue elements with up to 12 protons Supergiant formed. Slide 21 / 141 Slide 22 / 141 Periodic Table of Nucleosynthesis "We Are Made from Star Stuff" Atoms, the building blocks of matter, formed in the intense heat and pressure of the early universe, stellar furnaces and supernovae. Everything around us was once part of a star. In this course we will explore the nature of matter and apply principles of physics to understand atomic structure, chemical properties and predict chemical behavior. Click here to watch a video on the formation of the Elements. Slide 23 / 141 Slide 24 / 141 . Discovery of the Electron In the late 1800's scientists were passing electricity through glass tubes containing a very small amount of gas like oxygen. When the power was turned on, the tube emitted light and glowed. + - Atomic Structure: + - Electrons & Protons POWER POWER OFF ON The positive electrode is called the anode and the negative called the cathode. They called the rays "cathode rays" because they appeared to be coming from the Return to Table negative end of the tube. of Contents Actual Cathode Ray Tube
Slide 25 / 141 Slide 26 / 141 . Waves vs. Particles 4 Scientists found that they could deflect this beam by subjecting it to an additional electrical field. Students type their answers here There was much speculation about what these "cathode rays" were. Why would the beam deflect toward the positive plate? When an object was placed in the path of the rays, the rays cast Does that indicate the rays are light rays or particles? shadows of the objects placed in their path. - - + Light waves casts a shadow - so it could be light. + Or, it could be a stream of tiny POWER particles. ON Slide 27 / 141 Slide 28 / 141 6 Scientists determined that a very weak electrical field Scientists found that they could also deflect this beam by 5 could deflect the beam a great deal. subjecting it to a magnetic field. Students type their answers here Students type their answers here If the particles are really easy to deflect they either have Why would the beam deflect upward in the magnetic field a very small _______ or a very large _________ or both. above? Does that indicate the rays are light rays or particles? - - + + - + POWER POWER ON ON Slide 29 / 141 Slide 30 / 141 . . Negatively Charged Particles - Electrons Charge to Mass Ratio J.J. Thomson and team were able to determine this charge to Physicists proposed these negatively charged particles be called mass ratio to be: electrons. These particles have the same charge to mass ratio as the negative particles generated by static electricity, heated materials, and illuminated materials. 1.76 x10 11 Coulombs of charge/ kg of mass or C/kg Keep in mind, at this point they knew neither the charge nor the mass, just that the ratio was large indicating either a large charge or a small mass. What was very interesting was that these negatively charged particles were found in all gases they experimented on and they all had the same charge to mass ratio.
Recommend
More recommend
