Chemistry Unit 2 Test Questions

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Law of conservation of mass
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Mass is neither created nor destroyed during ordinary chemical reactions or physical changes
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Law of definite proportions
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A chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound
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Law of multiple proportions
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If two or more different compounds are composed of the same two elements then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers
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Dalton turned Democritus’ idea into a
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Scientific theory that could be tested by experiment
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Cathode ray
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Stream of particles
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Cathode rays are
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Negatively charged
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Cathode Rays have identical properties regardless of
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The element used to produce them
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Cathode ray experiments provides evidence that atoms are
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Divisible
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Who measured the charge of the electron
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Robert A. Millikan
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Because atoms are electrically neutral they must contain a
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Positive charge to balance the negative electrons
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Because electrons have so much less mass than atoms, atoms must contain
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Other particles that account for most of their mass
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Thomson proposed a model for the atom called the
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Plum pudding model
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Thomson believed negative electrons were
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Spread evenly throughout the positive charge of the rest of the atom
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Ernest Rutherford bombarded gold foil with
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Alpha particles
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The gold foil experiment led to the discovery of the
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Nucleus
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The nucleus was very
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Small compared to the total volume of an atom
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Niels Bohr proposed a model in which
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Electrons surrounded the positively charged nucleus
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All nuclei are made of two kind of particles
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Protons and neutrons
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Atoms are electrically neutral because they contain
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Equal numbers of protons and electrons
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The number of protons determines the
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Atoms identity
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When two protons are extremely close to each other there is a
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Strong attractions between them known as nuclear forces
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Electron cloud
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Cloud of negative charge
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Atomic number
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Number of protons of each atom of that element
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An elements atomic number is located
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Above its symbol
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The most common type of hydrogen is called
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Protium
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Protium, deuterium and tritium are
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Isotopes of hydrogen
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Isotopes
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Atoms of the same element that have different masses
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The isotopes if a particular element all have the same number of
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Protons and electrons but different numbers of neutrons
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Mass number
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Total number of protons and neutrons that make up the nucleus of an isotope
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Two methods for specifying isotopes
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Hyphen notation and nuclear symbol
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Nuclide
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General term for a specific isotope of an element
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The standard used by scientists to compare units of atomic mass is the
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Carbon-12 atom
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One unified atomic mass unit
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Is exactly 1/12 the mass of a carbon-12 atom
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Isotopes or an element may occur
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Naturally or in a laboratory
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Although isotopes have different masses, they do not
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Differ significantly in their chemical behavior
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Average atomic mass
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Weighted average of the atomic masses of the naturally accounting isotopes of an element
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Mole
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Amount of a substance that contains as many particles as there are atoms
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Number of particles in a mole
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Avagadro’s number
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One wave/second is a
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Hertz
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Max Planck proposed that
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A hot object would be expected if the energy emitted were in the form of waves
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Quantum of energy
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E= hv
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Electron orbits can be compared to
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Rungs on a ladder
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Atomis means
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Not to cut or indivisible
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Aristotle said that
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Matter could be cut continuously
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Most of an atom is
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Empty space, dense positive,t charged core
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Neutral atoms contain equal numbers of
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Protons and electrons
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Rutherford’s gold foil experiment led him to conclude that
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A dense region of positive charge existed somewhere in the atom
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What is not one of the five principles of Dalton’s theory
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All atoms gave similar physical and chemical properties
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According to the law of definite proportions any two samples of KCI will have
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The same elements in the same proportions by mass
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According to the law of conservation of mass when sodium hydrogen and oxygen react to form a compound the mass of the compound will be
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Equal to the sum of the masses of the reactants
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Thomsons experiment showed that the charge to mass rail of electrons was
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The same in all gases
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An atom has 19 protons and 20 neutrons. It’s mass number is
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39
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Compared with a mole of lead atoms a mole of its on atoms has
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The same number of atoms
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The molar mass of an element is numerically equal to
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The elements average atomic mass
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The units of molar mass are
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g/mol
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To determine the mass in grams of an atom of any element you would
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Divide the mass of a mole of the element by Avagadro’s number
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The average atomic mass of an element is
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The weighted average of all naturally occurring isotopes of the element
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The Ancient Greek philosopher that first proposed the notion of the atom was
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Democritus
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Which feature or Dalton’s atomic theory is different from modern atomic theory
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Atoms can not be subdivided
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The least massive particle in an atom is
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Electron
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The most massive particle in an atom is
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Neutron
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Protons are bound together by
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Strong nuclear forces
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Under what condition is a photon emitted from an atom
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When an electron moved from a high energy level to a low energy level
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What do quantum numbers describe
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Energy level, orbital shape, orbital orientation and spin state
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What is the relationship between the principal quantum number and the electron confuguration
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N describes the energy level
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List five examples of electromagnetic radiation
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Gamma rays, x Rays, ultraviolet light, infrared light, microwaves, radio waves
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What two experiments involving light and matter could not be explained by the wave theory of light
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Photoelectric effect and line emission spectrum
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How is hydrogen’s emission spectrum produced
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When electrons drop from higher energy orbits to lower energy
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What was a shortcoming of Bohr’s model of the atom
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Did not explain chemical nature of atoms
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What is the principal quantum number and how is it symbolized
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n- main energy level
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What are shells
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All orbitals with the same energy level
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The Aufbau principle
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Electron occupies lower energy orbital that can receive it
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Hund’s rule
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Orbitals of equal energy are occupied by 1 electron before being occupied by a second
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Pauli exclusion principle
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No 2 electrons in the same atom can have the same 4 quantum numbers
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What are inner shell electrons
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Electrons that are not in the highest occupied energy level
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How does noble gas notation simplify writing electron configurations
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Abbreviate large portions of the configuration
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A photon is emitted from a gaseous atom when an electron moves to its ground state from an
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Excited state
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When electromagnetic radiation strikes the surface of a metal, electrons are ejected from the metal surface. This is a description of the
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Photoelectric effect
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What describes the angular momentum number indicate
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The shape of an orbital
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What type of electromagnetic radiation had the lowest frequency
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Microwaves
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What can behave like a wave and also a stream of particles
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Electromagnetic radiation.
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When an atom in an excited state emits a photon of radiation the energy of the photon is equal to the
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Difference in energy between the atom’s excited state and its final stage
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The total number of orbitals that can exist at a given energy level is
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2n squared
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How many possible orientations does an s orbital have
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1
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How many possible values are there for the spin quantum number
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2
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In cathode ray tubes, the cathode ray is emitted from the negative electrode which is called the
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Cathode
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The smallest unit of an element that can exist either alone or in molecules containing the same or different elements is the
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Atom
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The behavior of cathode Rays in a glass tube containing gas at low pressure led scientists to conclude that the rays are composed of
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Negative particles
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The basic principles of atomic theory were first conceived by
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Dalton
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Neutral atoms of the same element can differ in
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Mass number
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The law of multiple proportions is demonstrated by the compounds
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CO and CO squared
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Millikans experiments led to the determination of the
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Approximate value of the electrons mass
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S orbitals are
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Spherical
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P orbitals are
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Dumbbell shaped
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D and F orbitals are
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More complex
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Level 1
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S
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Level 2
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S P
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Level 3
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S P D
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Level 4
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S P D F
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1st quantum number
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N- principal quantum number
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2nd quantum number
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L- orbital shape within an energy level
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3rd quantum number
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M- orientation of orbital in space
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4th quantum number
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S- spin of electron in orbital
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No two electrons in the same atom can have the same set of four quantum number
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Pauli Exclusion Principle
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N L M S are used to describe an
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Electron in an atom

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