Chapter 10 Organic Chemistry: Alkanes and Alkenes ✓ Flashcards
(32 cards)
What are hydrocarbons?
They are molecular compounds containing the elements hydrogen and carbon only.
They are the simplest of the organic compounds
What are the five main families hydrocarbons are classified into based on structural similarities?
-Alkanes
-Alkenes
-Cycloalkanes
-Cycloalkenes
-Aromatics
What is the general formula for alkanes?
CnH2n+2
Why are alkanes considered saturated and alkenes considered unsaturated?
-Alkanes are considered saturated hydrocarbons because they contain only single bonds between carbon atoms, meaning each carbon is bonded to the maximum number of hydrogen atoms.
-Alkenes are considered unsaturated hydrocarbons because they contain at least one carbon-carbon double bond, so they do not contain the maximum number of hydrogen atoms
Think of a reaction
What suffix does alkanes have?
-ane
What are structural isomers?
They are compounds that have the same molecular formula but different structural formulas.
This means they contain the same number and type of atoms, but the atoms are bonded in a different sequence
What alkanes do NOT have structural isomers?
-Methane (CH4)
-Ethane (C2H6)
-Propane (C3H8)
These molecules are too small an dsimple to have different arrangements of their atoms, so they cannot form structural isomers
What are position isomers?
They are compounds that have the same molecular formula and carbon skeleton but differ in the position of a functional group or substituent on the carbon chain
What is the difference between structural isomers and position isomers?
-Structural isomer have the same molecular formula but different arrangements of atoms, including differences in carbon chain structure of types of bonds
-Position isomers are a type of structural isomer where the carbon skeleton is the same, but the functional group or substituent is attached at different positions on the chain
What is the general rule for alkenes?
CnH2n
What suffix do alkenes have?
-ene
What types of isomerism can occur in alkenes, and what causes them?
-Alkenes can show position isomerism due to the different possible positions of the double bond along the carbon chain, and geometric (cis-trans) isomerism due to restricted rotation around the double bond and different spatial arrangements of atoms attached to the double-bonded carbons.
What are cis-trans isomers?
Cis-trans isomers have the same molecular and structural formula (meaning the same sequence of bonding between atoms) but a different spatial arrangement of their atoms.
Why do cis-trans isomerism occur in alkenes?
Because the double-bond prevents rotation along its axis, locking the position of the attached groups and resulting in two different spatial arrangements
Draw trans-but-2-ene and cis-but-2-ene
What is a substituent group?
An atom or group of atoms that replaces a hydrogen atom in the main carbon chain of a hydrocarbon.
What is a halogen in reference to organic chemistry?
Atoms from Group 17 of the periodic table that can replace hydrogen atoms in a hydrogen carbon to form haloalkanes
They include Fluorine, Chlorine, Bromine and Iodine
What determines the physical properties like melting point, boiling point and solubility of molecular compounds such as hydrocarbons?
The nature and strength of their intermolecular forces greatly influence the physical properties of molecular compounds like hydrogencarbons
How does the strength of molecular forces affect boiling point?
Boiling points increase with increasing strength of intermolecular forces
What is the only type of intermolecular force in hydrocarbons?
Hydrocarbons experience only dispersion forces as their intermolecular forces
What affects the strength of dispersion forces in hydrocarbons?
Dispersion forces are weak in molecules with few electrons and become stronger as the number of electrons increases or as molecular size increases.
How does molecular shape influence dispersion forces and boiling point in hydrocarbons?
Linear molecules allow maximum surface contact, resulting in stronger dispersion forces and higher boiling points than branches or spherical molecules of similar mass.
How is the effect of molecular shape of boiling point evident in structural isomers?
Structural isomers have the same number of electrons but different shapes, so their boiling points vary depending on how much surface contact their shape allows
What determines the solubility of molecular substances?
Solubility depends on the nature of intermolecular forces acting within substances - substance with similar types of intermolecular forces are generally soluble in one another.
