Chapter 22 Hydrocarbon Compounds – Flashcards
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How is the number of valence electrons in carbon atoms related to the bonds that carbon atoms form? |
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because carbon has four valence electrons, a carbon atom always forms four covalent bonds. |
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What are two possible arrangements of carbon atoms in an alkane? |
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the carbon atoms in an alkane can be arranged in a straight chain or in a chain that has branches. |
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In terms of their polarity, what type of molecules are alkanes? |
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molecules of hydrocarbons, such as alkanes, are nonpolar molecules. |
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Hydrocarbons |
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the simplest organic compounds contain only carbon and hydrogen. |
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Alkane |
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a hydrocarbon in which there are only single covalent bonds. |
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Straight-chain alkanes |
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contains any number of carbon atoms, one aftern the other, in a chain. |
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Homologous series |
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a group of compounds. the straight-chain alkanes are an example. there is a constant increment of change in molecular structuree from one compound in the series to the next. |
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Condensed structural formula |
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some bonds and/or atoms are left out of the structural formula. |
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Substituent |
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an atom or group of atoms that can take the place of a hydrogen atom on a parent hydrocarbon molecule. |
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Alkyl group |
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a hydrogen substituent. it can be one carbon or several carbons long. |
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Branched-chain alkane |
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an alkane with one or more alkyl groups. |
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What are the structural characteristics of alkenes? |
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at least one carbon-carbon bond in an alkene is a double covalent bond. other bonds may be single carbon-carbon bonds and carbon-hydrogen bonds. |
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What are the structural characteristics of alkynes? |
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at least one carbon-carbon bond in an alkyne is a triple covalent bond. other bonds may be single or double carbon-carbon bonds and single carbon-hydrogen bonds. |
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Saturated compounds |
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organic compounds that contain the maximum number of hydrogen atoms per carbon atom. |
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Unsaturated compounds |
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compounds that contain double or triple carbon-carbon bonds. |
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Alkenes |
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hydrocarbons that contain on or more carbon-carbon double covalent bonds. |
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Alkynes |
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hydrocarbons that contain one or more carbon-carbon triple covalent bonds. |
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Aliphatic hydrocarbons |
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straight-chain and branched-chain alkanes, alkenes, and alkynes. |
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How do structural isomers differ? |
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structural isomers differ in physical properties such as boiling point and melting point. they also have different chemical reactivities. |
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What two types of stereoisomers are there? |
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two types of stereoisomers are geometric isomers and optical isomers. |
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Isomers |
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compounds that have the same molecular formula but different molecular structures. |
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Structural isomers |
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compounds that have the same molecular formula, but the atoms are joined together in a different order. |
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Stereoisomers |
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molecules in which the atoms are joined in the same order, but the positions of the atoms in space are different. |
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Geometric isomers |
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atoms joined in the same order, but differ in the orientation of groups around a double bond. |
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Trans configuration |
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the methyl groups are on opposite sides of the double bond. |
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Cis configuration |
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the methyl groups are on the same side of the double bond. |
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Asymmetric carbon |
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a carbon with four different atoms or groups attached. |
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Optical isomers |
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pairs of molecules that differ only in the way that four different groups are arranged around a central carbon atom. |
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What is a cyclic hydrocarbon? |
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in some hydrocarbon compounds, the carbon chain is in the form of a ring. |
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What describes the bonding between electrons and carbons in a benzene ring? |
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in a benzene molecule, the bonding electrons between carbon atoms are shared evenly around the ring. |
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Cyclic hydrocarbons |
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compounds that contain a hydrocarbon ring. |
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Aromatic compound |
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an organic compound that contains a benzene ring or other ring in which the bonding is like that of a benzene. |
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What are the hydrocarbons found in natural gas? |
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natural gas is an important source of alkanes of low molar mass. |
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What is the first process used in the refining of petroleum? |
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the refining process starts with the distillation of petroleum (crude oil) into fractions according to boiling-point. |
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What are the two variables used to classify coal? |
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coal is classified by its hardness and carbon content. |
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What is the chemical composition of coal? |
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coal consists largely of condensed aromatic compounds of extremely high molar mass. these compounds have a high proportion of carbon compared with hydrogen. |
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Cracking |
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a controlled process by which hydrocarbons are broken down or rearranged into smaller, more useful molecules. |