1. Dopamine
That initial giddiness that comes when we're first falling in love includes a racing heart, flushed skin and sweaty palms. Researchers say this is due to the dopamine, norepinephrine and phenylethylamine we're releasing. Dopamine is thought to be the "pleasure chemical," producing a feeling of bliss. Norepinephrine is similar to adrenaline and produces the racing heart and excitement. According to Helen Fisher, anthropologist and well-known love researcher from Rutgers University, together these two chemicals produce elation, intense energy, sleeplessness, craving, loss of appetite and focused attention. She also says, "The human body releases the cocktail of love rapture only when certain conditions are met and ... men more readily produce it than women, because of their more visual nature."
They discovered that people in love have lower levels of serotonin and also that neural circuits associated with the way we assess others are suppressed. These lower serotonin levels are the same as those found in people with obsessive-compulsive disorders, possibly explaining why those in love "obsess" about their partner.
In romantic love, when two people have sex, oxytocin is released, which helps bond the relationship. According to researchers at the University of California, San Francisco, the hormone oxytocin has been shown to be "associated with the ability to maintain healthy interpersonal relationships and healthy psychological boundaries with other people." When it is released during orgasm, it begins creating an emotional bond -- the more sex, the greater the bond. Oxytocin is also associated with mother/infant bonding, uterine contractions during labor in childbirth and the "let down" reflex necessary for breastfeeding.

2. Norepinephrine

3. phenylethylamine

4. serotonin 5-hydroxytryptamine (5-HT)
5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal (GI) tract, platelets, and in the central nervous system (CNS) of animals including humans. It is popularly thought to be a contributor to feelings of well-being and happiness.[5]
5-hydroxytryptamine (5-HT)

5. oxytocin
1-{[(4R,7S,10S,13S,16S,19R)-19-Amino-7-(2-amino-2-oxoethyl)-10-(3-amino-3-oxopropyl)-13-[(2S)-2-butanyl]-16-(4-hydroxybenzyl)-6,9,12,15,18-pentaoxo-1,2-dithia-5,8,11,14,17-pentaazacycloicosan-4-yl]car bonyl}-L-prolyl-L-leucylglycinamide

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Aldehydes and Ketones
Aldehydes and ketones are common products when alcohols react with molecular oxygen and are said to be more oxidized than alcohols.
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7. Aldehydes and Ketones Formaldehyde is toxic to humans and animals.
It is a gaseous compound at normal temperatures and pressures, and is used to prepare plastics, to preserve biological specimens, as an embalming fluid, and as a domestic disinfectant.
It is commonly used as a 40% solution in water called formalin.

8. Copyright W. H. Freeman and Company · New York
Acetaldehyde is an air pollutant.
Acetaldehyde is most often encountered as an air pollutant.
It is produced by the partial oxidation of ethanol.
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9. Aldehydes often occur naturally in fruits and other plants.

12. Copyright W. H. Freeman and Company · New York
Synthetic aldehydes are often used in perfumes:
prime component in Chanel No. 5:
Perfumes are complex mixtures which evaporate in three stages called the top, middle, and base notes.
Aldehydes are used as one of the top notes, the first scents we smell in a perfume.
Copyright W. H. Freeman and Company · New York

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Aldehydes and Ketones
Ketones have two carbon groups bonded to the C=O carbon
Ketones have two carbon chains or rings attached to the carbonyl group. The names of most ketones end in –one.
The simplest ketone is acetone:
Acetone is good solvent for many organic compounds and is the major component in nail varnish remover.
Copyright W. H. Freeman and Company · New York

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Vitamins
Vitamin C is water soluble because it contains many hydroxyl groups.
Vitamin C is required for the production of collagen, an important connective tissue.
A deficiency of vitamin C results in the disease, scurvy, characterized by skin lesions and tooth loss.
Vitamin C is found in fresh fruits and vegetables, especially citrus fruits.
Copyright W. H. Freeman and Company · New York