Chapter 6 Flashcards
What is the shape and properties of group two?
linear, 180°, 2 bond pair and no lone pairs
What is the shape and properties of group 3?
Trigonal planar, 120°, 3 bond pairs and no lone pairs
What is the properties and shape of group 4?
Tetrahedral, 109.5°, 4 bond pairs and no lone pairs
What is the shape and properties of group 5?
Pyramidal, 107º, 3 bond pairs and one one pair
What is the shape and properties of group 6?
Non-linear, 104.5°, 2 bond pair 2 lone pair
Why are electrons equally spaced out?
Repulsion’s are equal
What happens to the shape it lone pairs are present?
Shape is distorted
Why is the shape distorted with the addition of lone pairs?
Extra repulsion is caused by lone pairs
How much do lone pairs push bond angle down by?
2.5°
How many bonding pairs does an octahedral have? What is the bond angle
6 pairs, 90°
What is electronegativity?
A measure of the tendency of an atom to attract a bonding pair of electrons in a covalent bond
What happens it you increase the electronegativity?
Increases the electrons attracted to it
What are the three factors affecting electronegativity?
Atomic charge,distance from nucleus, electron shielding
How does electronegativity increase in the periodic table?
Across the groups and up the period
Would the dipole be negative or positive it the atom was more electronegative than the other?
Negative
What happens to the dipole is there is a greater difference of electronegarivity?
Greater permanent dipole
What is a permanent dipole?
The charge difference between two bonded atoms of different electronegativities
Are symmetrical bonds polar or non polar?
Non polar
What are symmetrical molecules?
There are not just areas of just positive or just negative charge
Which is the most electronegative element?
Fluorine
What effect on polarity do lone pairs have?
Can cancel out dipoles created by bonding pairs
What are intermolecular forces?
Weak interactions between dipoles of different molecules
What are London forces? And what are they caused by?
Weak intermolecular forces caused by very small dipoles in molecules.
What are factors affecting strength ?
The greater the number of electrons in each molecule,the larger the oscillating and induced dipoles and the greater the attractive forces between molecules
What is a polar molecule?
A molecule which atoms have significant differences in their electronegativity and a dipole created
What elements can hydrogen bonding occur?
Fluorine, nitrogen and oxygen
What is hydrogen bonding?
Special type of dipole-dipole interaction
Why does hydrogen only bond with specific atoms?
Hydrogen has a high density and F,N and O are highly electronegative
What is the best example of hydrogen bonding?
Water
What happens to water when it freezes?
The density decreases
What is the structure of ice and what happens to it when it melts?
Diamond structure and it will collapse
What happens to most simple molecular lattices (minus h20)?
They sublime, water doesn’t due to the hydrogen bonds
What properties do water get from hydrogen bonds?
Relatively high viscosity and surface tension
What happens to the surface tension on q liquid if you disrupt the hydrogen bonds?
It decreases
