Electronegativity Flashcards
Electronegativity is
Electronegativity is the tendency of an atom to attract the bonding pair of electrons towards itself.
Electronegativity of F; Cl; O; H
F - 4; Cl - 3; O - 3.5; H - 0.7
Electronegativity trends in a Periodic Table(might as well recall overall trends dummy)
Up and across the Periodic Table the Electronegativity increases.
Overall rules
Across —>:
Greater nucleus and its attraction.
Same shielding.
Less distance from the nucleus.
Down:
Greater nucleus and its attraction.
More shielding.
Greater distance from the nucleus.
Polarity of bonds in terms of electronegativity(not so important but you’re insane and far gone and wanna learn it so here you go ig)
higher electronegativity - lower(in a bond)
<0.5 - Non-polar covalent bond
0.4-0.9 - Slightly polar
1-1.3 - Moderately polar
1.4-1.7 - Highly polar
1.8-2.2 - Slightly ionic
2.3+ Ionic
Explain polarity
When there is slightly positive and slightly negative end in a molecule, electrons in that kind of bond stick closer to a more electronegative atom.
Difference between Ionic and Polar bonds
In Ionic bond nearly all of the electrons of the pair are attached to a more electronegative atom, the difference in electronegativity is greater and the charges are taken a s full charges.
Do Polar bonds determine whether the whole molecule is polar?
Explain.
No. The polarity of a molecule depends on its shape, if the charges are ‘evenly distributed’ e.g. trigonal planer shape - the molecule itself is not polar. If one side of a molecule has delta -ve charge and the other has delta +ve - that molecule is indeed polar.
Intermolecular forces (definition) -
Unlike intramolecular forces(forces inside the molecule, such as bonds) intermolecular forces are forces between the molecules.
What intermolecular forces are there?
- Permanent dipole-dipole(van der Waal force)
- Instantaneous(Induced) dipole-dipole(also van der Waal force)
- Hydrogen bonds*
Define Dipole -
A polar molecule(a molecule that has slightly positive and slightly negative end)
Define permanent dipole-dipole forces(check your understanding girl)
Permanent dipole-dipole forces occur between two polar molecules. A negative end attaches to a positive one in all directions in a 3D space.
Explain electron density
Since electrons are very fast they create areas of electron density we also call orbitals, they’re that fast that for human eye they just occupy the whole area ig so that means, for example, two electrons can be on the opposite sides of a p-orbital, as well as on one of them at the other moment.
Explain Induced dipole-dipole
Induced dipole-dipole interaction happens when in one non-polar molecule the electron density shifts to one side, creating a slightly negative charge on that side and slightly positive on another, that creates a momentary dipole. This dipole then induces the other non-polar molecule, by either attracting its electrons to a more positive side or repulsing them with a more negative one and that way attracting each other for a moment. This and Permanent dipoles are stronger when more electrons are present.
Define Hydrogen bonding
Hydrogen bonding - when a Hydrogen atom is bonded to O; F or N; Cl and other electronegative atoms are too big to form a Hydrogen bond. This bond is stronger than other intermolecular forces but only 1/10 of a covalent bond.
Water forms the most effective form of Hydrogen bond.
Put intermolecular forces in order from weakest to strongest.
- Induced dipole-dipole
- Permanent dipoles-dipole
- Hydrogen bond
