Properties Flashcards
What is the definition of polarity?
Polarity is a separation of charge which tells us whether a molecule will dissolve in water or boil at a certain temperature.
What is electronegativity?
The bonding attraction of atoms.
Which atoms have the highest electronegativity?
The top right of the periodic table.
Which atoms have the lowest electronegativity?
The bottom left of the periodic table.
What are the requirements to make a non-polar covalent bond in terms of atoms?
There needs to be no real charge difference across the molecule. OR atoms need to be the same or symmetrical.
Why do non-polar covalent bonds have no separation of charge?
They are similar or have the same electronegativity’s.
What are the requirements to form a polar covalent bond in terms of atoms?
There needs to be a difference in electronegativity between the atoms. (unsymmetrical)
Why are alkanes, alkenes and alkynes non-polar?
They have a symmetrical shape.
Are haloalkanes polar or non-polar?
They are polar when the molecule is small with a strong haloalkanes, but they are non-polar most the time as the long carbon chain is too strong and balances out.
Which organic molecules are always considered polar?
Haloalkanes - when small
Compounds with oxygen - when small
Compounds with nitrogen
Carboxylic acids.
How are solids converted to liquids and how is liquid converted to gas.
All substances exist as gases liquids and solids at different temperatures and pressures. By increasing the temperature solids break down into liquid. This is the same for liquid to gas.
What are the 3 intermolecular forces and their relative strength?
- Instantaneous dipole-dipole forces between all molecules (WEAK)
- Permanent dipole-dipole forces in polar molecules (MED)
- Hydrogen bonding between molecules which has a hydrogen bonded to a highly electronegative atom. (STRONG)
What is the name of the attractive force that holds molecules together?
Intermolecular forces
Why do alcohols have higher melting/boiling points than alkanes, alkenes and alkynes?
They are held together by stronger forces.
Do straight or branched chains have higher melting/boiling points and why?
Straight chains. The straighter the chain the closer molecules are together therefore greater forces exist.
