Module 4: Alkanes Flashcards
(17 cards)
What’s a sigma bond?
A type of covalent bond, when atomic orbitals overload head on. Sigma bonds can rotate freely.
What’s an alkane?
A homologous series with the general formula CnH2n+2
What’s boiling point?
The temperature where a liquid becomes a gas. Branched alkanes have higher boiling points, London forces weaker so less energy needed to overcome.
Whats bond Enthaply?
Energy needed to break a mole of gaseous bonds. Actual bond Enthaply differ, due to a range being considered.
Whats complete combustion?
When a compound is burnt in a very good supply of oxygen. Only products are water and carbon dioxide.
What’s a covalent bond?
A strong bond between 2 atoms due to electrostatic attraction shared between a pair of electrons and atomic nuclei
What’s electron pair repulsion?
Electrons repel each other as far as possible, this creates the shape of a molecule, alkanes have a tetrahedral shape, 109.5 degrees.
Whats homolytic fission?
A covalent bond breaks, each atom receives an electron, forming 2 radicals.
Whats incomplete combustion?
A compound is burnt with limited oxygen. When alkanes are combusted this way, water, carbon monoxide and some carbon dioxide can be produced.
Whats initiation?
First step in radical substitution mechanism, forms radicals
What are London forces?
Induced dipole - dipole interactions caused by the random movement of electrons, this causes a knock on effect.
What’s a polar bond?
A covalent bond that has a permanent dipole due to electronegative difference.
Whats propagation?
The middle steps in a radical substitution, radical reacts with different species.
What’s a radical?
A species with an unpaired electron
Whats radical substitution?
Type of substitution, a radical replaces another atom/ group in a compound. Alkanes can undergo radical substitution with chlorine or bromine when present in UV, forming a mixture of organic products.
Whats termination?
Final stage of radical substitution, 2 radical reacts with together, forming a species with paired electrons.
Whats tetrahedral?
Shape of molecule in which the central atom has 4 bonded electron pairs.
