Electronegativity & IMF Flashcards
(12 cards)
What is Valence Shell Electron Pair Repulsion (VSEPR) Theory?
Electron pairs repel each other to get as far away from each other as possible. Lone pair, lone pair repulsion is greater than lone pair, bonding pair which is greater than bonding, bonding pair repulsion.
What is electronegativity?
The power of an atom to attract a pair of electrons in a covalent bond.
What are the 3 factors affecting electronegativity?
Nuclear charge, atomic radius and shielding.
What happens to electronegativity down a group?
Decreases- due to increased shielding and atomic radius so bonding pair of electrons are further from nucleus.
What causes a permanent dipole?
A shift in electron density between 2 atoms.
Why is H2 not a polar molecule?
The electrons in the covalent bond are being attracted by the same amount by each atom.
Are symmetrical (on different side of the atom, e.g. SF6) or asymmetrical molecules polar?
Asymmetrical- charge unevenly spread out, not cancelled out by each other.
What are the 3 types of intermolecular forces?
Van der Waals forces, Dipole- dipole forces & Hydrogen bonding.
How do Van der Waals forces arise?
Electron move in molecule which creates a dipole. Induces dipole on neighbouring molecule. Temporary dipoles are attracted to each other.
How do permanent dipole-dipole forces arise?
Occurs between molecules with a permanent dipole. Electronegativity leads to bond polarity. Attraction between delta positive on one molecule and delta negative on another molecule.
What is hydrogen bonding?
Occurs when hydrogen is bonded to nitrogen, oxygen or fluorine atom. Delta positive H on one molecule is attracted to lone pair on N,O or F on a neighbouring molecule.
Weakest to strongest intermolecular forces:
Van der Waals forces (weakest), Dipole-dipole, Hydrogen bonding.
