The symptoms of influenza (flu) appear suddenly and often include: 1  Fever of 100.4Â°F (38Â°C) to 104Â°F (40Â°C), which can reach 106Â°F (41Â°C) when symptoms first develop. 2  Body aches and muscle pain (often severe), commonly in the back, arms, or legs. 3  Headache. Pain when you move your eyes.
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electrostatic force of attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction. double bond between two atoms is formed by the sharing of two pairs of electrons, one in a sigma bond and one in a pi bond, with electron density concentrated on two opposite sides of the internuclear axis.
a type of chemical bond involving the sharing of electrons between atoms in a molecule, esp the sharing of a pair of electrons by two adjacent atoms. covalent bond in Medicine Expand. covalent bond n. A chemical bond formed by the sharing of one or more electrons, especially pairs of electrons, between atoms. covalent bond. A chemical bond formed when electrons are shared between two atoms. Usually each atom contributes one electron to form a pair of electrons that are shared by both atoms. See more at coordinate bond, double bond, polar bond.