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 double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that is between two carbon atoms, can be found in alkenes. Many types of double bonds exist between two different elements. For example, in a carbonyl group with a carbon atom and an oxygen atom. Other common double bonds are found in azo compounds (N=N), imines (C=N) and sulfoxides (S=O).