Electronegativity and Bond Polarity Flashcards
what is electronegativity
the ability of an atom to attract a bonding pair of electrons
how does the electronegativity of elements change down a group
it decreases
how does the electronegativity of elements change across a period
it increases
what one word describes the distribution of electron density between two of the same atoms (from the same element) bonded together
symmetrical
why is the electron density distribution symmetrical in this case
- because as they are the same atom
- their ability to attract the bonding pair of electrons between them is identical
- so the electron density isnt skewed to one side
what does the electron density map of molecules look like
- contour map
- they correspond to the electron density
what will the electron density distribution of hydrogen chloride simply be like and why
- it would be unsymmetrical
- as hydrogen and chlorine have different electronegativities
given that the nucleus of a chlorine atom has a higher electronegativity than hydrogens, what would the electron density map of hydrogen chloride look like
- the contour lines would be more closely spaced near the chlorine atom
- the lines would closer together
- and there would be more contour lines
- resulting in a pear shaped density map
because the chlorine atom has attracted the bonded electrons closer to it, what would the charges of the chlorine and hydrogen corners be
- the chlorine side would have a slight negative charge
- while the hydrogen side would have a partial positive charge
what would these differing partial charged be noted with
o+ and o- on their respective sides
what is this kind of bond therefore called
a polar (covalent) bond
using the format H-Cl, what are the two ways you could show this polarity
- draw the o+ and o- at the top right of the elements
- like H^o+ - Cl^o-
- or draw an arrow within the bond (the arrow head in the middle of the bond) to show the direction of electron drift
