Electronegativity Flashcards
When is the only time the sharing of electrons in a covalent bond is equal?
When both atoms are the same
What would be an example of an equal share of electrons in a covalent molecule?
O2, Cl2
Why is the sharing of electrons in a molecule with two different atoms not always equal?
The ability of an atom in covalent to attract the bonded pair of electrons is down to its electronegativity.
What does the Pauling Scale do?
It assigns values of electronegativity to element, 4 being the highest, 0 being the lowest.
What happens to electronegativity as you move down a group?
Electronegativity decreases
What happens to electronegativity as you move across a period?
Electronegativity increases
Where are the most electronegative elements found?
Top right of the periodic table
What is a ‘pure’ covalent bond?
Equal sharing of electrons, electrons are found roughly half way between 2 atoms in a covalent bond
Are electrons attracted to higher or lower electronegativity?
Higher
What happens in a molecule where one element is more electronegative than the other?
The more electronegative element will become more electron dense and so will be slightly negative while the other element becomes slightly positive.
What is formed when one side of a molecule is slightly negative and one side is slightly positive? (2 terms)
A polar bond is formed and so the molecule is called a permanent dipole.
What happens if one element in a molecule is a lot more electronegative than another?
The pair of electrons is dragged over to the more electronegative atom which has gained complete control of the electrons. An ion is formed.
Why is there no clear cut between ionic and covalent bonding?
There is no answer to how fair a pair of electrons can be dragged by a more electronegative element until it becomes ionic.
Is CCl4 polar? Why?
No, there is no overall separation of charge as the molecule as a whole does not have a side which is slightly + or -.
What molecules with a specific shape will not be polar?
Symmetrical molecules with the same element around a central atom will cancel out the dipoles.
