Chem Ch 4 Pt 1

25 July 2022
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question
About how many different kinds of atoms (elements) are found in nature?
answer
91
question
What scientist formalized a theory of the atom that gained broad acceptance?
answer
Dalton
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What are three main ideas in Dalton's atomic theory?
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All atoms of an element are identical, and each element has unique atoms. Elements are composed of atoms. Atoms combine to form compounds in simple, whole number ratios.
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Rutherford performed the gold foil experiment to ________.
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confirm the plum pudding model
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The element magnesium has significantly fewer protons and neutrons than gold. If you were to use Mg in place of Au in the Rutherford experiment, how would you predict the results from the experiment to change?
answer
The center spot would be smaller and the alpha particle scattering would be reduced.
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How do the results of the Rutherford experiment suggest that the nucleus is positively charged?
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The large center spot is caused by small alpha particle deflections when they pass by a positively charged nucleus.
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Which of the following statements about the electron is true?
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Electrons are negatively charged particles.
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Work done after Rutherford's gold foil experiment demonstrated that the nucleus contained ________.
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protons and neutrons
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What are the main ideas in the nuclear theory of the atom?
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*An atom is electrically neutral, so the number of negative particles (electrons) is equal to the number of positive particles (protons). *The positive charge of an atom is located in the center of the atom called the nucleus, which also contains nearly all of the mass of the atom. *An atom is almost entirely empty space, which is occupied by extremely small, negatively charged particles called electrons
question
List the three subatomic particles.
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proton,neutron,electron
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Enter the masses of these particles in kilograms.
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mp, mn, me− = 1.67262×10^−27,1.67493×10^−27,9.1×10^−31 kg
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Enter the masses of these particles in atomic mass units.
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mp, mn, me− = 1.0073,1.0087,5.5×10^−4 amu
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Enter the charges of these three particles in terms of elementary charge.
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qp, qn, qe− +1,0,-1
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Inside Nucleus
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neutron, proton
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Outside Nucleus
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Electron
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Which of the following statements is true about the properties of protons, neutrons, and electrons?
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Positive and negative charges attract.
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Is matter usually charge-neutral?
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Yes
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names that reflected the properties of the elements
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argon and bromine
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elenents named after countries
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americium, francium and poloniu
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elements named after scientists
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curium and mendelevium
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What is a chemical symbol?
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A chemical symbol is a one or two letter abbreviation that is unique to each element.
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An element is defined by ________.
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the number of protons
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What scientist noticed that certain groups of elements had similar properties?
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Mendeleev
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How is the periodic table organized?
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The modern periodic table is organized by increasing atomic number, which is the number of protons found in each element.
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What is the main idea in the periodic law?
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The periodic law showed that while the elements have unique properties, there is a periodic repetition of similar properties.
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What elements are located on the left side of the periodic table?
answer
metals
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Where on the periodic table are metalloids found?
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The metalloids make up the zigzag section that separates the metals and the nonmetals which is found running from boron to astatine.
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What are the properties of nonmetals?
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Nonmetals can be found as solids, liquids, or gases. Nonmetals are poor conductors of heat and electricity. Nonmetals tend to gain electrons in reactions.
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Where are nonmetals found on the periodic table?
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Nonmetals make up the upper right side of the periodic table.
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What are the properties of metals?
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Metals conduct heat and electricity. Metals have shiny appearance. Metals are ductile. Metals are malleable. Metals tend to lose electrons in reactions
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Where are metals found on the periodic table?
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Metals make up the left side section of the periodic table.
question
Locate each of the following on the periodic table and give their group number.
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alkali metals-1A alkaline earth metals-2A halogens-7A noble gases-8A
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Which term represents the sum of protons and neutrons?
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mass number
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What is an ion?
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An ion is an atom or group of atoms that becomes electrically charged due the gain/loss of electrons.
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What is an anion?
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This is a negative ion formed when an atom or group of atoms gains one or more electrons.
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What is a cation?
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This is a positive ion formed when an atom or group of atoms loses one or more electrons.
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Group 1A
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+1
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Group 2A
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+2
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Group 3A
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+3
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Group 6A
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-2
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Group 7A
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-1
question
The mass number of an isotope is the _______ of _________________ found in the nucleus of the particular isotope.
answer
sum, the number of protons and the number of neutrons
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The first method for specifying isotopes is to __________ and __________ the mass number and t____________, respectively, on the ________ side of the chemical symbol.
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superscript, subscript, the atomic number, left
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The second method is to identify the element followed by _____________
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the mass number.
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What is the atomic mass of an element?
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The atomic mass of an element is really the average mass of the element calculated accounting the masses of each isotope and how common the isotope is found in nature.
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The percent natural abundance of isotopes provides _____________ of each isotope found in a sample of the element. For a given element, ___________ of each different isotope in a naturally occurring sample of that element are always _________
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the relative amounts, the relative amounts, the same.
question
Magnesium has three naturally occurring isotopes with masses of 23.99, 24.99, and 25.98 amu and natural abundances of 78.99%, 10.00%, and 11.01%. Calculate the atomic mass of magnesium.
answer
Atomic mass of Mg = 24.31 amu
question
Copper has two naturally occurring isotopes: Cu−63 with mass 62.9395 amu and a natural abundance of 69.17%, and Cu−65 with mass 64.9278 amu and a natural abundance of 30.83%. Calculate the atomic mass of copper.
answer
Atomic mass of Cu = 63.55 amu
question
Rubidium has two naturally occurring isotopes: Rb−85 with mass 84.9118 amu and a natural abundance of 72.17%, and Rb−87 with mass 86.9092 amu and a natural abundance of 27.83%. Calculate the atomic mass of rubidium.
answer
Atomic mass of Rb = 85.47 amu
question
Silicon has three naturally occurring isotopes: Si−28 with mass 27.9769 amu and a natural abundance of 92.21%, Si−29 with mass 28.9765 amu and a natural abundance of 4.69%, and Si−30 with mass 29.9737 amu and a natural abundance of 3.10%. Calculate the atomic mass of silicon.
answer
Atomic mass of Si = 28.09 amu