Physics Ch. 11 – Flashcards
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Who advanced the idea of atoms in the early 1800s?
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John Dalton
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What causes dust particles and tiny grains of soot to move with Brownian motion?
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Collisions with invisible molecules
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Who first explained Brownian motion and made a convincing case for the existence of atoms?
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Albert Einstein
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How does the approximate number of atoms in the air in your lungs compare with the number of breaths of air in Earth's atmosphere?
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The numbers are the about the same, 10^23.
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Are most of the atoms around us younger or older than the Sun?
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Most are older than the Sun.
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Why can't atoms be seen with a powerful optical microscope?
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Atoms are much smaller than a wavelength of light.
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Why can atoms be seen with an electron beam?
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The wavelength of the electrons is smaller than an atom.
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What is the purpose of a model in science?
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A model is an abstraction that helps us visualize and predict.
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Where in the atom is most of its mass concentrated? What is this mass composed of?
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In the nucleus as protons and neutrons
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What is meant by the term nucleon?
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A proton or neutron
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How does the electric charge of a proton compare with the electric charge of an electron?
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It is equal and opposite.
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Since atoms are mostly empty space, why don't we fall through a floor we stand on?
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Electrons in one atom repel the electrons in another.
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What element has the lightest atoms? What is the most abundant element in the known universe?
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Hydrogen
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How are most of the elements with nuclei heavier than those of hydrogen and helium formed?
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Nuclear fusion in stars
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Where did the heaviest elements originate?
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Nuclear fission in supernovas
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What are the five most common elements in humans?
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C, H, O, N, and Ca
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What does the atomic number of an element tell you about the element?
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The number of protons in its nucleus
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How many shells are represented in the presently known periodic table?
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7
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What kind of attraction pulls electrons close to the atomic nucleus?
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Electric
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Why aren't heavier elements much larger than lighter elements?
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The larger positive charge in the nucleus pulls the electrons into closer orbits.
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How does one isotope differ from another?
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It has a different number of neutrons.
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Distinguish between mass number and atomic mass.
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Mass number is the number of nucleons; atomic mass is the total mass of an atom.
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What is a compound? Cite two examples.
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Atoms of different elements with bonds between them: NaCl and H2O
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What is a mixture? Cite two examples.
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Atoms pressed together without bonding: air and salt and sand
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How does a molecule differ from an atom? Give an example.
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A molecule is composed of two or more atoms bonded together: H2O.
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Compared with the energy it takes to separate oxygen and hydrogen from water, how much energy is released when they recombine?
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The same amount of energy is released when they recombine.
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How do matter and antimatter differ?
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When matter and antimatter meet, they annihilate in a flash of energy.
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What occurs when a proton and an antiproton meet?
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They annihilate each other.
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What is the evidence that dark matter exists?
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Gravitational forces within galaxies are too great to be accounted for with ordinary matter.
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Where were the atoms that make up a newborn infant "manufactured"?
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Atoms were "manufactured" in the stars that exploded in the origin of the universe, before the Sun and Earth came into existence. Depending on the weight of the atoms, lighter ones were created deep within stars, while heavier ones were formed in the implosion and explosion of supernovas.
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Somebody told your friend that if an antimatter alien ever set foot upon Earth, the whole world would explode into pure radiant energy. Your friend looks to you for verification or refutation of this claim. What do you say?
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While the meeting of antimatter and matter would result in a transformation of radiant energy, the amount of matter reacting would only equal the amount of antimatter reacting. Thus, if the antimatter alien set foot on Earth, only an amount of Earth equal to the alien's mass would react and explode.
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Your friend says that what makes one element distinct from another is the number of electrons about the atomic nucleus. Do you agree wholeheartedly, partially, or not at all? Explain.
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partially. Another characteristic and distinguishes elements is the number of protons in one's nucleus (the atomic number)
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The atomic masses of two isotopes of cobalt are 59 and 60. What is the number of protons in each? What is the number of neutrons in each? What is the number of orbiting electrons in each when the isotopes are electrically neutral?
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cobalt-59, cobalt-60 = 27 protons each. Isotopes still have the same atomic number. 32 neutrons,33 neutrons. Subtract the protons from the isotope number to find the specific number of neutrons. (p+n=isotope#) 27 electrons each (matches proton #, which is again same for each)
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You could swallow a capsule of germanium without ill effects. But, if a proton were added to each of the germanium nuclei, you would not want to swallow the capsule. Why?
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Germanium, the apparently harmless element, has 32 protons (atomic number 32). Adding a proton to a germanium nuclei would give it properties of a 33 proton element- this happens to be Arsenic! As we know, Arsenic is poisonous.
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The atoms that constitute your body are mostly empty space, and structures such as the chair you're sitting on are composed of atoms that are also mostly empty space. So why don't you fall through the chair?
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Electrons in one atom repel the electrons in another atom. The same goes for the positively charged nucleii. Repulsion increases rapidly as the nucleii get closer to each other. Also, solid material molecules are held together by various kinds of bonds. These bonds (chemical) would need to be broken to pass through. This would require a significant amount of energy!
