Electronegativity and Polarity Flashcards
1
Q
Define electronegativity.
A
The attraction of a bonded atom for the pair of electrons in a covalent bond
2
Q
What is the most electronegative element?
A
Flourine
3
Q
What is the difference between a polar bond and a non polar bond?
A
- A polar bond is when the bonded electron pair is shared unequally between the bonded atoms as a result of different electronegativities, this is a permanent dipole
- A pure covalent bond is when the bonded electron pair is shared equally between the bonded atoms
4
Q
What is a polar molecule?
A
- When the molecule is unsymmetrical and the dipoles do not cancel out
5
Q
Are CO2 and H20 polar molecules?
A
Co2 = dipoles cancel, non polar
H20 = dipoles do not cancel, polar
6
Q
What are three types of intermolecular forces?
A
- Induced dipole - dipole interactions (london forces)
- Permanent dipole - dipole interactions
- Hydrogen bonding
7
Q
How are induced dipole - dipole interactions formed?
A
- there is movement of electrons that produce a changing dipole in a molecule
- at any moment, there is an instantaneous dipole
- the instantaneous dipole induces a dipole on a neighbouring molecule
- The induced dipole induces further molecules which attract one another
8
Q
How does the strength of induced dipole - dipole interactions vary?
A
- The more electrons
- The larger the instantaneous and induced dipoles
- The greater the induced dipole - dipole interactions
- The stronger the attractive forces between molecules
9
Q
What is the trend with the number of electrons and boiling point?
A
- The more electrons, the greater the strength of the london forces and therefore the more energy required to overcome the london forces
- This increases boiling points
10
Q
What is a simple molecular lattice?
A
- Molecules are held by weak intermolecular forces
- the atoms within each molecule are held by strong covalent bonds
11
Q
What are the properties of simple molecular lattices?
A
- Low melting point and boiling point due to weak london forces
-Soluble in non - polar solvents - Can not conduct electricity as there are no mobile electrons