# Chem 1210 Ch2 HW

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Because some drops had picked up more electrons than others. A drop that had picked up more electrons would have a greater charge. A drop with fewer extra electrons would have a lesser charge.
Why did different drops have different charges?
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5 electrons
Based on the given data, how many extra electrons did drop C contain?
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3.6Ã—10?15 Z The smallest increment in charge corresponds to the charge on a single electron.
In Millikan's experiment, the charge on each drop of oil was measured in coulombs. Imagine the same experiment, but with charges measured in a fictitious unit called a zeet (Z). Drop / Charge (Z) A) 2.16Ã—10?14 B) 3.60Ã—10?14 C) 3.96Ã—10?14 D) 4.32Ã—10?14 E) 5.76Ã—10?14 What is the charge on an electron in zeets?
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4.0Ã—10?22 w When Millikan did his experiment, he knew that the charge-to-mass ratio of an electron was 1.76Ã—10^8 C/g. Using this and the newly discovered charge on an electron, 1.60Ã—10?19 C, he was able to determine the mass of an electron in grams: electron mass=(1.60Ã—10^?19 C) / (1.76Ã—108 C/g) =9.10Ã—10^?28 g
A single electron has a charge of 3.6Ã—10?15 Z . Using zeets and a fictitious unit of mass called the wiggle, w, the charge-to-mass ratio of an electron is 8.9Ã—106 Z/w . What is the mass of an electron in wiggles?
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*Particles of the cathode rays are fundamental to all matter. *There are subatomic size particles in an atom. *Cathode rays have mass. *Matter contains negative charge and by inference positive charge. Cathode rays were later to become known as electronsâ€”a term coined by another scientist, George Stoney. The "plum-pudding" model of the atom, with an atom as a sea of positive charge in which were embedded the negatively charged electrons, resulted from these initial experiments by Thomson. Listed in chronological order, Thomson's cathode ray tube experiments, Millikan's oil-drop experiment, and Rutherford's alpha-particle scattering experiments were among the most significant.
Based on the data Thomson collected in his experiments using cathode rays, the concept of atomic structure was modified. Which of the following statements about the atomic structure were validated by his cathode ray experiments?
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*charge on an electron *mass of an electron Although significant contributions were made as a result of the oil-drop experiments, the arrangement of the electrons within the atom was still just a theoretical proposal.
Based on the data gathered in Millikan's oil-drop experiments, the concept of atomic structure was modified. Which of the following aspects of the structure of the atom was validated by these experiments?
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*the nuclear density being large *the charge on the nucleus being positive *most of the atomic volume being empty space *the existence of the atomic nucleus Although the Rutherford nuclear model of the atom was a significant advance in the development of atomic structure, it left many questions unanswered such as how to account for the total mass of an atom. The existence and characterization of the proton and the neutron at a later date answered many of these questions. However, the list of particles that make up the nucleus is very large and continues to grow as new particles are characterized by current experiments in atomic physics.
Based on the data gathered in the Rutherford's scattering experiments, the concept of atomic structure was modified. Which of the following aspects of the structure of the atom were validated by these experiments?
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X= 2 There is a 3:1 ratio for the masses of fluorine per gram of sulfur in the two compounds. This is an example of the law of multiple proportions, which supports atomic theory.
There are two different compounds of sulfur and fluorine. In SF6, the mass of fluorine per gram of sulfur is 3.55 g F/g S. In the other compound, SFX, the mass of fluorine per gram of sulfur is 1.18 g F/g S. What is the value of X for the second compound?
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N2O, N2O4, N2O5
If you were John Dalton and had never heard of a mole, which of the following would you think were possible sets of formulas for the compounds A, B, and C, respectively?
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Hydrogen and oxygen form both water and hydrogen peroxide. A decomposition of a sample of water forms 0.125 g hydrogen to every 1.00 g oxygen. The decomposition of a sample of hydrogen peroxide forms 0.0625 g hydrogen to every 1.00 g oxygen. Show that these results are consistent with the law of multiple proportions.
The law of definite proportions and the law of multiple proportions allowed us to discover that matter consists of discrete units, called molecules or compounds, in which the ratio of elements in each molecule is consistent. We understand now that every water molecule (H2O) is composed of two atoms of H and one atom of O, but, before these proportional laws were formulated, we could only observe the mass ratios of hydrogen to oxygen in different compounds.
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mass number = 9
The atomic number of boron is 5. What is the mass number of a boron atom with 4 neutrons?
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31 15 P
Give the nuclear symbol for the isotope of phosphorus for which A=31 ?
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88.3 amu Usually the relative atomic mass of an element is closest to the isotope that makes up the majority of the natural abundance. In this example, isotope 3 had the largest relative abundance. Therefore the relative atomic mass was closer to the mass of isotope 3 than to any of the other isotopes.
What is the relative atomic mass of a hypothetical element that consists of the following isotopes in the indicated natural abundances?
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58.7 amu Can you figure out which element this is by looking at the periodic table? Although the relative atomic masses of nickel and cobalt are very close, these are the isotopic abundances of nickel. Nickel-58 is the most abundant isotope, so it is expected that the relative atomic mass of nickel is closest to the mass of nickel-58.
What is the relative atomic mass of the element that consists of the following isotopes in the indicated natural abundances?
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Np, Ne = 13,10 protons, electrons
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Np, Ne = 34,36 protons, electrons
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Np, Ne = 26,23 protons, electrons
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Ca
A certain element forms an ion with 18 electrons and a charge of +2. Identify the element.
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... very different from the properties of the elements that compose them.
The properties of compounds are generally ...
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... an entirely new substance results.
When two elements combine to form a compound, ...
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a ball and stick model an empirical formula a structural formula a molecular formula a space-filling model The type of formula or model you use depends on how much information you have about the compound and how much you want to communicate.
What are the different ways to represent compounds? Why are there so many?
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covalent
What type of bondâ€”ionic or covalentâ€”forms between nitrogen and oxygen?
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Classify the following compounds as having covalent or ionic bonds. Drag the appropriate compounds to their respective bins. Phosphorus trichloride, sulfur trioxide, barium chloride, potassium iodide, aluminum sulfide, strontium iodide
The use of the prefixes mono, di, and tri is also a sign that those compounds contain covalent bonds. Those prefixes are not used in ionic compounds to specify the number of anions in the formula. However, there are a few polyatomic anions that have prefixes in their name, such as dichromate.
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stannic iodide
SnI4 Spell out the full name of the compound.
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chromium(II) sulfide
CrS Spell out the full name of the compound.
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rubidium fluoride
RbF Spell out the full name of the compound.
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barium bromide
BaBr2 Spell out the full name of the compound.
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barium nitrate Barium is a metal that has only one oxidation state. Therefore it is not necessary to write II in parentheses in the systematic name. Only those metals with more than one oxidation state must have its state written in the name.
Give the systematic name for the compound Ba(NO3)2.
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iron(III) sulfate Although it seems like a small difference, iron(II) and iron(III) behave much differently chemically. They even form different-colored compounds because of the number of electrons they have to bond. Therefore it is very important to specify which oxidation state is being used.
Give the systematic name for the compound Fe2(SO4)3
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BeO All of the elements in group 2 form ions with a +2 charge. That is because all of these elements need to lose two electrons to gain stability. After losing the electrons, there is an excess of two protons, which results in a +2 charge.
Enter the formula for the compound beryllium oxide
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Pb3(PO4)2 Lead, like iron, has more than one oxidation state, so it is necessary to put the oxidation state of the metal in parentheses. Elements in group 1 and 2 only have one oxidation state and so there is no need for Roman numerals in their systematic name.
Enter the formula for the compound lead(II) phosphate.
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magnesium nitrate
What is the systematic name of Mg(NO3)2?
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ammonium chlorate
What is the systematic name of NH4ClO3?
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What is the systematic name of PbO?
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NO
What is the formula for the compound nitrogen monoxide?
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P4O10 Submit
What is the formula for the compound tetraphosphorus decoxide?
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CH4
What is the formula for the compound methane?
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NCl3 is a molecular compound (two or more nonmetals), and therefore in its name prefixes indicate the number of each type of atom-?so NCl3 is nitrogen trichloride. The compound AlCl3 is an ionic compound (metal and nonmetal), and therefore does not require prefixes-?so AlCl3 is aluminum chloride.
The compound NCl3 is nitrogen trichloride, but AlCl3 is simply aluminum chloride. Why?
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carbon disulfide
CS2 Spell out the full name of the compound.
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methane
CH4 Spell out the full name of the compound.
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tetranitrogen tetraselenide
N4Se4 Spell out the full name of the compound.
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iodine heptafluoride The prefix mono- is not included on the first element, however if there were two or more iodine atoms, then the appropriate prefix would be necessary.
What is the name for the compound IF7? Spell out the full name of the compound.
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dinitrogen tetrahydride Since there are 2 atoms of nitrogen in the molecule, the prefix di is necessary.
What is the name for the compound N2H4? Spell out the full name of the compound.
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sulfur trioxide This compound is a molecular compound containing only nonmetals. The prefix mono is dropped for the first element, and the ending of the second element is changed to ide.