OZ - Electronegativity Flashcards
What is electronegativity?
The ability of an atom to attract the binding electrons in a covalent bond.
What is electronegativity usually measured using?
The Pauling scale.
What does the size of the electronegativity value suggest about the electronegativity of the element?
The higher the electronegativity value, the more electronegative the element.
What is the most electronegative element?
Fluorine - has a value of 4 on the Pauling scale.
Apart from fluorine, what other elements are also very strongly electronegative?
Oxygen, chlorine and nitrogen.
How high is the value of the most electronegative element?
4.0
How low is the value of the least electronegative element?
Around 0.7
How does electronegativity change across the periodic table?
It increases as you move towards fluorine.
How does electronegativity change across periods?
Increases.
How does electronegativity change down groups?
Decreases (ignoring the noble gases).
What might covalent bonds be polarised by?
Difference in electronegativity.
In covalent bonding, where do the bonding electrons sit?
In orbitals between 2 nuclei.
When will covalent bonds be non-polar?
If both atoms have similar or identical electronegativities and so the electrons will sit roughly midway between the 2 nuclei and the bond will be non-polar.
In what molecules will covalent bonds be non-polar and why?
In homonuclear, diatomic gases (e.g. H2 and Cl2) because the atoms have equal electronegativities and so the electrons are equally attracted to both nuclei.
When will covalent bonds be polar?
If the bond is between 2 atoms with different electronegativities making the bonding electrons get pulled towards the more electronegative atom. This causes the electrons to be spread unevenly and so there will be a charge across the bond (each atom has a partial charge - one atom is slightly positive and the other is slightly negative).
