chem lewis structure test

describe the difference between localized and delocalized bonding when does each occur and given an example for each?

electrons are delocalized, meaning the electrons can move around the molecule, only resonance structures have delocalizes

what’s a polar bond

when two different atoms are bonded together, and there’s an unequal sharing of electrons, did strengths, one has higher ET

what symbols are used to represent a separation of charge?

S^+ = partial pos (weaker element)

S^- =partial neg (stronger element)

→ =dipol arrow=points towards more ET atom

what’s a non polar bond

when two of the same atoms are bonded together, (diatomica) and share electrons equal equally, equal strength

what are resonance structures? What is the actual structure?

attempts to represent a real structure that is a mix of several possibilities

actual structure is an average of all the resonance structures

in resonance molecules what is actually moving between structures? What is not moving?

in resonance structures, only the electrons can move not the atoms

how do you determine the central atom in a lewis structure?

The least electronegative element excluding hydrogen

what element can never be the central atom in a lewis structure

Hydrogen

what’s electronegativity?

Measures how strongly the atoms attract an electron in a bond

which group of elements have high and low electronegativity values

Non metals = high electronegativity values (want to attract e)

metals= low electronegativity values

which group of elements don’t have electronegativity values?

noble gases

what’s the trend for electronegativity going across a row and going down a group?

when you go across the row, it increases when you go down a group it decreases

define intermolecular forces

forces between molecules that result in the physical properties of the substance

which state of matter has the strongest intermolecular force attractions in which state of matter has the weakest?

solids are strong, liquids have moderate,

and gases are weak

4 types of IMF

Ion Dipole= metal +non metal (allows compounds to be soluble

hydrogen bonding= when H is directly bonded to N,O,F (polar molecule)

Dipole-Dipole= cause by the attraction of polar molecules

London Dispersion Forces= Non polar molecules, weakly attractive forces between molecules

A region of positive and negative charge are found in which type of molecule

a polar molecule

IMF determine what properties of a substance

it dictates the physical properties of molecules (boiling point,melting point)

if the central atom has at least one or more sets of ____ it means the molecule is ___

lone pairs, polar

what’s a dipole moment

the measurement of the overall polarity of a molecule

greatest dipole moment= whichever one is the strongest

overall dipole moment= the polar molecule

which types of IMF are polar and non polar

polar - dipole-dipole, hydrogen bonds, ion dipole

non polar- LDF