A hydrogen bond is a weak type of chemical bond that is common in organisms. As the name suggests, this type of bond involves a hydrogen atom that is attracted to a strongly electronegative atom such as oxygen, fluorine, or nitrogen of a polar covalent bond in the same or another molecule.
An investment grade is a rating that indicates that a municipal or corporate bond has a relatively low risk of default. Bond rating firms, such as Standard & Poor's and Moody's, use different designations consisting of upper- and lower-case letters 'A' and 'B' to identify a bond's credit quality rating.
In this case the covalent bonds are shown by the lines and the shared electrons are shown by the black dots. When ionization of the carboxyl group occurs a proton dissociates from the OH group, leaving the shared electrons behind with the oxygen.
Bond secured by a lien on the bond issuer's assets and payable from the issuer's income. Unlike a mortgage backed pass-through security (which conveys an ownership right), these bonds instead offer a more predictable maturity and, thus, a type of call protection against the bond's early redemption.