Chapter 4 Study Guide Atoms – Flashcards
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Dalton's atomic theory stated that every element was made of atoms that could not be subdivided, atoms of the same element are alike, and :
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Atoms of different elements could form to join compounds.
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Which statement about the atom's nucleus is correct?
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The nucleus is made of protons and neutrons and has positive a charge.
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According to Rutherford's model of the atom, electrons behave like:
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Planets orbiting the sun.
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Oxygen's atomic number is 8. This means that an oxygen atom has:
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eight protons in its nucleus
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Which statement about an element's average atomic mass is correct?
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it is weighted average, so common isotopes have a greater effect than uncommon ones.
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A mole is an SI base unit that describe the:
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amount of a substance.
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If the average atomic mass of carbon is 12.01 u, 1 mole of pure carbon will have a mass of ?
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12.01 g
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The average atomic mass of potassium is approximately 39 u. What is the mass of the 2.0 mol of potassium?
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78 g
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You have 6.50 mol of chromium, which has a molar mass of approximately 52 g/mol. What is the mass in grams of this amount of chromium?
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338 g
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Which statement about the modern model of the atom is not true?
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Electrons can be found between energy levels.
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The first theory of atoms, proposed by---------, suggested that the universe was made of unit that could not be divided.
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Democritus
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The nucleus of an atom had a -------- electric charge.
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Positive.
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Bohr's model of the atom compares electrons with ------.
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Planets.
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Isotopes of an element have the same atomic-------but different atomic --------.
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Number, Masses
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The-------is the SI unit that is used for counting small particles, such as atoms.
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Moles
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The molar mass of krypton is 83.80 g/mol. The mass of 5.00 mol krypton is----------g.
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419
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Thomson's study of cathode rays revealed that atoms contained negatively charged particles called-------.
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Electrons
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The number of energy levels that are filled in atoms is determined by the number of--------.
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Electrons
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An atom gains energy by absorbing a light particle call a(n)
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Photons
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Explain the major differences between Bohr's model of the atom and the modern model.
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Bohr's model-miniature solar system with the electrons surrounding the nucleus as planets do. Modern Model- similar to the blades of a fan and moving so fast the exact location cannon be determined.
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Which statement is true according to Dalton's theory?
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Atoms of the same element are exactly alike.
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According to Bohr's theory, an electron's path around the nucleus defines it
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Energy level
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An atom's mass number equals the number of
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Protons plus the number of neutrons
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A unified atomic mass unit is equal to
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one-twelfth the mass of a carbon-12 atom
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Avogadro's number is defined as the number of particles in
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One mole of a substance
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Molar mass is defined as
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the mass in grams of one mole of a substance.
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The average atomic mass of the element cesium is approximately 133 u. What is the mass of 3.00 mol of cesium?
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399 g
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What is the mass in grams of 0.75 mol sulfur, which has a molar mass of approximately 32 g/mol?
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24g
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Which of the following statements about the modern model off the atom is true?
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Electrons can only be found in certain energy levels.
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Thomson's cathode-ray tube experiment supported the theory that-----exist inside an atom.
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electron
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Rutherford's gold-foil experiment revealed that an atom'positive charge is concentrated in the atom's-------.
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Nucleus
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The first person who suggested that matter was made up of atoms was the Greek Philosopher--------.
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Democritus
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Neutrons and protons are found in the ------of an atom.
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Nucleus
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According to modern atomic theory, the exact location of a(n)---- is uncertain.
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electron
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An atom of potassium has an atomic mass of 39 u and an atomic number of 19. It therefore has-----neutrons in its nucleus.
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20
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The molar mass of palladium iis 106.42 g/mol. Therefore, 53.2 g of palladium contains-------mol.
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.500
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When an atom gains or loses energy, ------ jump between energy levels.
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electrons
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The chemical properties of an atom are determined by------which are located in the atom's outer energy level.
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Valence electrons
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Explain why atoms have no electric charge even though they are made up of charged particles.
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electrons are negative and protons are positive so they cancel each other out.
