Electronegativity

• Electronegativity is a measure of the attraction of a bonded atom for the pair of electrons in the covalent bond.
• Electronegativity is measured using the Pauling scale, which was invented by Linus Pauling, a chemist who is known for his work on electronegativity.
• In general, electronegativity increases across a period and up a group, as the charge on the nucleus increases across a period.
• Electronegativity increases across a period because the number of protons in the nucleus increases, attracting the outer electrons more strongly.
• Electronegativity increases up a group because the bonding pair of electrons is held increasingly further away from the nucleus as the number of shells increases.
• Polar bonds occur when one atom in a bond is more electronegative than another.
• In a polar bond, the differing attraction for the pair of electrons allows there to be a small charge difference between the atoms.
• The electrons in a polar bond are held closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.
• Polar bonds are permanent dipoles, with a small charge difference always present.
• Non-polar bonds occur if the two bonding atoms are identical, as their attraction for the shared pair of electrons is equal and the electrons are equally distributed between the bonding atoms.
• In a non-polar bond, the bond is perfectly covalent.
• Carbon dioxide has a linear shape and is non-polar.
• Molecules are non-polar if they are symmetrical.
• Dichloromethane is a polar molecule because it is not symmetrical and the dipoles do not cancel out.
• Chlorine is more electronegative than carbon and hydrogen, which have roughly equal electronegativities, making chlorine more electronegative.
• Nitrogen trifluoride has a pyramidal shape and is not symmetrical, making it polar.
• In magnesium iodide, a small difference in electronegativity between the magnesium and the iodine results in polarization of the bond, with the electrons shared unequally and resulting in an uneven distribution of charge.
• A molecule is polar if there is a difference of electronegativity and a difference in charge.
• Silicon tetrachloride has a central silicone surrounded by four chlorine atoms and has a tetrahedral structure, making it non-polar.
• Boron trifluoride has a symmetrical trigonal planar shape, resulting in cancellation of dipoles and making it non-polar.
• Ammonia does not have a symmetrical shape and is polar.
• Boron trifluoride has a trigonal planar shape and is symmetrical, making it non-polar.
• Carbon hydrogen and chlorine can form the molecule dichloromethane (CH2Cl2), which takes a tetrahedral shape and has polar bonds.
• Electronegativity is the tendency of an atom in a bond to attract the electrons to itself and can be measured on the periodic table.
• Non-polar bonds are when the two bonding atoms are identical and the electrons are equally distributed between the bonding atoms.
• In nonpolar molecules, the symmetry of the molecule means the effect of any permanent dipoles is cancelled out and there is no difference in charge across the molecule.
• Silicon tetrachloride, carbon dioxide, ammonia, and bo are examples of polar and non-polar molecules.
• A molecule is non-symmetrical if a difference in charge exists across the molecule, resulting in an overall dipole.
• The lateral density relates the probability of finding electrons at a particular position in space, represented as a cloud of electrons around the nucleus.
• Polar bonds exist on a spectrum, from ionic bonding at one end to covalent bonding at the other.
• A molecule is symmetrical if the dipoles resulting from the bond between the atoms cannot cancel each other out, resulting in no overall dipole.
• Electron density is the probability of finding electrons at a particular position in space, represented as a cloud of electrons around the nucleus.
• Polar bonds are when the two bonding atoms are different and their attraction for the shared pair of electrons is unequal.
• If there is a difference in electronegativities of two atoms, the molecule is polar.
• Molecules containing polar bonds are not always polar, but the symmetry of polar bonds within the molecule can cancel out the effect of any permanent dipole.
• In polar molecules, a difference in charge exists across the molecule, resulting in an overall permanent dipole.
• If there is no difference in electronegativities of two atoms, the molecule is nonpolar.
• When drawing Lewis structures, the bonded electrons are represented as a line between two atoms, visualized as being shared equally between those two atoms.
• In reality, electrons are not shared equally between two atoms, as different elements differ in their electronegativities.
• The more electronegative an atom is, the greater pull that atom will have on the shared electrons in a bond.