Bonding Flashcards
Define average bond enthalpy
A measurement of covalent bond strengths
What are the six bonds shapes we need to know?
- Linear
- Trigonal planar
- Tetrahedral
- Pyramidal
- Non-linear
- Octrahedral
Define Linear and give an example
Define trigonal and give an example
Octaheral shape - 6 bonds with an angle of 90 degrees between each one
Describe tetrahedral and give an example
Describe pyramidal and give an example
Describe non-linear and give an example
2 bonded pairs and 2 lone pairs. the 2 lone pairs push the bonded pairs even closer otgether reducing the angle to 104.5 (change of 2.5 degrees each time) H2O
Describe octaheral
6 bonds with an angle of 90 degrees between each one
What is electron pair repulsion?
When the lone pairs are closer to the central atom so repel more strongly than the bonded pair
Define electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond. It increaces up the periodic table and across to the right of the periodic table meaninf flourine is the most elcronegative
What is the difference of electronegativity in a covalent bond
0
What is the difference of electronegativity in a polar bond?
0-1.8
What is the difference of electronegativity in an ionic bond?
1.8 as the large difference in electronegativity means that the stronger atom will gain control of the electrons creating a postive na dnegative ions
What are permanent dipoles and where do they occur?
Delta positive or LISTEN TO THIS BIT AGAIN before 3.19
What are intermolecular forces?
The attractions between dipoles which create the physical properities of a molecule
Name the intermolecular forces and their strengths
Hydrogen bonds - strongest
Permaanent dipole interactions - Stronger that induced, weaker than hydrogen bonds
Induced dipole interactions - weakest
What are induced dipole-dipole forces also known as?
London forces and Van der waals forces. They are when instantaneously electrons move closer or further away to atoms creating instantaneous dipoles which then create a ripple effect on neighbouring molecules creating dipoles that only last for a second
hydrogen bonding is a permanent dipole between a hydrogen atom and either flourine, oxygen or nitrogen. It is hydrogen bonding that gives water its unusual properties for example ice is less dense than water, ususually high melting anf boiling points and high surface tension and viscousity
Define simple molecular lattices
When molecules are held together by weak inermolecular forces, the atomw within the molcule are held together by very strong covalent bonds. These lattices have low melting and boiling points because they will easily break up into their individual moecules due to the weak forcees between them. They dont conduct electricity because the molecules are all held togetherindividually so there are no charges available
Non-polar molecules (molecules without a charge) will be soluble in non-polar solvents because the interactions will weaken the intermolecular forces and cause it to break up and dissolve. However non-polar molecules are insoluble in polar solvents because the polar bonds are too strong to break so there’s no interaction between the molecules and solvent
Polar substances are soluble on polar solvents
