Bonding Flashcards
What is ionic bonding
Strong electrostatic forces of attraction between oppositely charged ions held in a lattice
Why do ionically bonded substances have high melting and boilling points
Requires alot of energy to break the strong electrostatic forces of attraction between opposites charged ions
Giant ionic structures:regular structure,cubic shape,repeating pattern
Do ionic compounds conduct electricity? Why?
Yes, When molten/in solution as the ions are free to move and carry charge through the strcture
as solids they cannot as they are in a fixed shape
(they also tend to dissolve in water as they are polar)
What is molecular covalent bonding
A shared pair of electrons that has Weak van der waals forces of attraction between molecules
Can molecular covalent molecules conduct electricity? why?
No- all electrons used in bonding and aren’t free to move
Do molecular covalent substances have a high/low melting and boiling point? why?
Low- Weak van der Waals forces of attraction between molecules that don’t take much energy to overcome
Why do macromolecular covalent bonds have high MP and BP
Requires lots of energy to overcome the many strong covalent bonds
Why do metallic compounds have high MP and BP
Strong forces of attraction between metal ions and negatively charged sea of delocalised electrons
Do macromolecular covalent bonds conduct electricity
Most don’t as all electrons are used in bonding
Why do metallic compounds conduct electricity
The delocalised electrons move throughout the metal and to carry charge
Examples of molecular covalent substances
Iodine
Ice
CO2
Water
Methane
Define metallic bonding
The electrostatic force of attraction between the positive metal ions and the delocalised electrons
What conditions are required for hydrogen bonding to occur?
- Partial charge on H and F/N/O
- Hydrogen attracted to the lone pair of O/N/F
- Large Electrobegativity diff
When is a dative/co-ordinate covalent bond formed
When an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone pair of electrons
what does the electron pair repulsion theory state
that electron pairs will take up positions as far away from each other as possible to minimise the repulsive forces between them
Which experiences the most repulsion?
(Lone pair-Lone pair
Lone pair-Bond pair
Bond pair-Bond pair)
Lp-Lp strongest repulsion
Lp-Bp repulsion middle
Bp-Bp repulsion weakest
what are the main factors affecting the strength of Metallic bonding
Number of protons( the more protons the stronger the bond)
Number of delocalised electrons(more delocalised= stronger)
Size of ion(the smaller the ion the stronger the bond)
When does a dipole dipole occur
When the elements in the bond have diff electronegativities around 0.3 to 1.7
What is the main factor affecting size of Van der Waals forces
The more electrons there are in the molecule the more VDW forces
Poperties of Dipole Dipole
Occur between polar molecules
Stronger than VDW
Assymetrical
Hydrogen bonding
A hydrogen attacthed to the three most electronegative compounds NFO and must have an available pair of lone electrons
U draw the line from the h bond to the lone pair
which atoms are the most electronegative
F N O CL
What is a polar molecule
When there is an electronegatibity diff between two or more atoms in a molecule
How can the shape of a molecule have an effect on the size of VDW forces
Long staright chains have a large surface area so they have stronger VDW whilst chains with kinks have a lower surface area
