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13 Cards in this Set
- Front
- Back
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From the chemist's point of view, what are the essential differences among a proton, a neutron, and an electron?
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Electon - negative charge
Proton - positive charge Neutron - no charge |
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Distinguish between an atom and an ion.
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An atom is the smallest particle of an element that can enter into a chemical reaction.
An ion is a positively or negatively charged atom or group of atoms. |
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What letters are used to designate atomic number and mass number in isotopic notation of atoms?
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Z represents the atomic number
A represents the mass number |
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In what ways are isotopes alike?
In what ways are they different? |
They each have the same number of protons and electrons but different numbers of neutrons.
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What is a mole?
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The amount of a substance containing the same number of formula units (6.022 x 10 ^23) as there are in exactly 12 g of ^12C. One mole is equal to the molar mass in grams of any substance.
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Whick would have a higher mass: a mole of K atoms or a mole of Au atoms?
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A mole of gold has a higher mass than a mole of potassium.
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What is the relationship between Avogadro's number and the mole?
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Avogadro's number
(6.022 x 10^23): is the same number of formula units in 1 mole |
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What is the difference between an empirical formula and a molecular formula?
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The empirical formula is the simplest formula giving the smallest whole number ratio of atoms present in a compound.
The molecular formula is the true formula representing the total number of atoms of each element present in one molecule of the compound. |
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A neutron is approximately how many times heavier than an electron?
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Actual Mass of a:
Electron 9.110 x 10 ^-28 Neutron 1.675 x 10^-24 |
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What is the purpose of balancing equations?
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To represent the quantitative relationships of a reaction, the chemical equation must be balanced. The balanced equation therefore obeys the law of conservation of mass.
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What is represented by the numbers (coefficients) that are placed in from of the formulas in a balanced equation?
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Balance each element (one at a time) by placing whole numbers (coefficients) in front of the formulas containing the unbalanced element: begin with metals, then nonmetals, then H and O.
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Explain how endothermic reactions differ from exothermic reactions.
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In endothermic reactions energy must be added to start and continue to be added to sustain the reaction.
In exothermic reactions this energy is returned and more is released, which allows the reaction to continue on its own. |
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What is a combustion reaction? How can you identify whether a reaction is a combustion reaction?
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A combustion reaction is an exothermic process (usually burning) done in the presence of oxygen.
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