Lecture 17 Flashcards
Electronegativity
A blue describing how well an atom can attract electrons in a molecule
- derived directly from bond energies
Electron affinity
Amount of energy released when an electron is added to an atom
Pauling electronegativity scale
A numerical scale of electronegativies based on bond energy calculations for different elements joined by covalent bonds
Why are smaller elements more electronegative?
Positively charged nuclei are closer to electron density
Ionic bond
No sharing e-
Large electronegativity difference
ex. NaCl, KBr
Polar covalent
Unequally sharing e-
Electronegativity difference in the middle
ex. HCl, HI
No polar covalent
Equal sharing e-
Small electronegativity difference
ex. H2, Cl2
ΔEN values for mostly ionic compounds
1.7-3.3
ΔEN values for polar covalent compounds
0.4-1.7
ΔEN for mostly covalent (no polar) compounds
0-0.4
Bo bonds need to be only ionic or only covalent?
No there is a continuum
Electronegativity
The ability of an atom in a covalent bond to attach the shared electron pair
Metallic bonding
Metal is held together by the attraction between metal cations and the sea of valence electrons
Group 2 had higher ________ than group 1
Melting points
Why do metals bend instead of crack?
Metal ions slide past each other through electron sea and end up in a new position
