ElectronegativityThe electronegativity of an element is a measure of the power of attraction of an atom for a shared pair of electrons in a covalent bond
Trends across the periodic table Electronegativity increases from left to right across the periodic table as the number of valence electrons increase Electronegativity values decrease from the top to the bottom in any group as the atomic radii increases Metals are the least electronegative elements, while non-metals are the most electronegative
Electronegativities of Elements Electronegativity
Electronegativity gives an indication of bond type The bigger the difference in electronegativity the more ionic the bond is.
Electronegativity values can be used to predict bond types A difference in electronegativity between two atoms of >1.7 indicates that the bond is ionic A difference in electronegativity between two atoms of <1.7 indicates that the bond is covalent Polar Covalent: An uneven share of electrons. Electronegativity difference of more than zero but less than 1.7
100% covalent compounds 100% covalent compounds have a electronegativity value of zero. This generally only happens when they are the same element. e.g. F and F 6
Bond Polarity and Electronegativity Electronegativity and Bond Polarity• There is no sharp distinction between bonding types.• The positive end (or pole) in a polar bond is represented δ + and the negative pole δ-. HyperChem
Example H and F Hydrogen has a electronegativity value of 2.1. Fluorine has a electronegativity of 4.0. The difference between them is 1.9 => Ionic in character
Investigate the bond type between the following atoms Which of the following compounds are ionic, fully covalent or polar covalent?H and FH and SH and NC and OH and HCl and ClNa and BrMg and OK and FH and HHow would you describe the bonding in the following compounds?CaO, NH3, AlCl3 9
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