Lesson Plan: Valentine’s Day Chemistry
FOR THE TEACHER
Submitted by
Marie Thomas
Springville High School
Springville, Utah
Summary
In this lesson, students learn about the chemistry of love. They see
chemical structures of compounds involved in the biological process of love and learn about
some of the chemical changes associated with love.
Grade Level
High or middle school
Objectives
By the end of this lesson, students should be able to
 Understand some of the chemistry involved with love
Chemistry Topics
This lesson supports students’ understanding of
 Chemical changes
Time
Teacher Preparation: 15 minutes
Lesson: 65 minutes (all four parts, each part’s estimate is listed below)
Materials
 PowerPoint
Safety
No specific safety considerations need to be observed during this lesson.
Teacher Notes
 I find that students love learning about the changes going on in their body when love is
involved. They often share this information with their friends and family.
 Some information included for the PowerPoint may be too mature for your students. The
information is intended for the teacher’s background, and it’s up to them what they want
to share with their students. All sources are provided, so teachers can cater the lesson to
what they are comfortable sharing with their students.
FOR THE STUDENT
Lesson
 Show the Valentine PowerPoint (30 minutes)
 Talk about Valentine gifts (15 minutes)
 Relationship demos (10 minutes)
 Valentine minute-to-win-it (10 minutes)
Information for PowerPoint
From: “How Love Works,” “The Chemistry of Love,” “The Science of Love,” “Chocolate: The Love Drug … And Why
It’s Good for You”
Love happens in three stages, and each stage involves different chemicals in the body.
Lust testosterone, estrogen
Attraction phenylethylamine, epinephrine, dopamine, serotonin, pheromones
Attachment oxytocin, vasopressin, endorphins
Attraction
Phenylethylamine (PEA) (C8H11N)
It is an organic compound that plays the role of a neurotransmitter in the central nervous
system of humans and other mammals. This endogenous chemical is naturally present in the
brain and helps focus, reduce stress, and regulate mood. It has the ability to release
noradrenaline, a stimulant hormone, which gives a boost to your heart rate, blood pressure, and
blood flow. Low levels of this compound have been connected with attention deficit
hyperactivity disorder , along with certain types of depression. Abnormally high levels of this
chemical have been observed in schizophrenic patients. The giddiness and feeling of high that
one experiences during intimate moments is due to the increased concentration of this
compound in the brain. It is also present in high levels in chocolate. Therefore, many a time,
chocolate is referred to as a comfort food. PEA present in it gives the feeling of happiness and
increases confidence levels.
Epinephrine (C9H13NO3)
The initial stages of falling for someone activate your stress response, increasing your blood
levels of adrenalin and cortisol. This has the charming effect that when you unexpectedly bump
into your new love, you start to sweat, your heart races, and your mouth goes dry. Epinephrine is
also known as adrenaline.
Dopamine (C8H11NO2)
In addition to releasing oxytocin, hugs also stimulate brains to release dopamine, the pleasure
hormone. Dopamine sensors are the areas that many stimulating drugs such as cocaine and
methamphetamine target. Helen Fisher asked newly love struck couples to have their brains
examined and discovered they have high levels of the neurotransmitter dopamine. This chemical
stimulates desire and reward by triggering an intense rush of pleasure. It has the same effect on
the brain as taking cocaine. Fisher suggests “couples often show the signs of surging dopamine:
increased energy, less need for sleep or food, focused attention, and exquisite delight in smallest
details of this novel relationship.”
Serotonin (C10H12N2O)
One of love's most important chemicals that may explain why when you’re falling in love, your
new lover keeps popping into your thoughts. A landmark experiment in Pisa, Italy, showed that
early love (the attraction phase) really changes the way you think. Dr .Donatella Marazziti, a
psychiatrist at the University of Pisa, gathered 20 couples who had been madly in love for less
than six months. She wanted to see if the brain mechanisms that cause you to constantly think
about your lover were related to the brain mechanisms of Obsessive-Compulsive Disorder
(OCD). By analyzing blood samples from the lovers, Dr. Marazitti discovered that serotonin
levels of new lovers were equivalent to the low serotonin levels of OCD patients.
Pheromones
These are chemicals that are excreted by the body and are known to induce various reactions in
other beings who are at the receiving end. There are various kinds of pheromones, but sex
pheromones are the ones important in this context. They are dubbed as the silent signals that
mammals send out to each other with the help of smell and other olfactory means. These signals
are believed to be signs for them to find and identify an appropriate sexual partner. They are
known to change the behavior of the opposite sex and sometimes even trigger sexual excitement
in them. Although there is no evidence of them being present in humans, various studies have
proved that smell plays a vital role in human mating and selection of a partner.
Attachment
Oxytocin (C43H66N12O12S2)
When we hug someone, oxytocin is released into our bodies by our pituitary gland, lowering
both our heart rates and our cortisol levels. Cortisol is the hormone responsible for stress, high
blood pressure, and heart disease. Oxytocin is the hormone that is also responsible for us being
here today. It is released during childbirth, making our mothers forget about all of the
excruciating pain they endured birthing us and making them want to still love and spend time
with us. Diane Witt, an assistant professor of psychology, has showed that if you block the
natural release of oxytocin in sheep and rats, they reject their own young. Conversely, injecting
oxytocin into female rats who’ve never had sex, caused them to fawn over another female’s
young, nuzzling the pups and protecting them as if they were their own
Endorphins
These are the body's natural painkillers and also play a key role in long-term relationships. They
produce a general sense of well-being, including feeling soothed, peaceful, and secure. Like
dopamine and norepinephrine, endorphins are released during sex; they are also released
during physical contact, exercise, and other activities. According to Michel Odent of London's
Primal Health Research Center, endorphins induce a "drug-like dependency."
So back to the question about chocolate being a comfort food …
Chocolate
Chocolate gets right to the heart of sexual pleasure by increasing the brain’s level of
serotonin, the feel-good brain chemical. Serotonin plays a major role in positive mood,
emotional health, proper sleep, and balanced appetite, contributing to numerous behavioral
and physiological functions. Decreased serotonin is a well-known factor in cases of
depression. Increased brain serotonin promoted by chocolate increases sexual excitation,
desire, and responsiveness. Women have more serotonin in their systems than men and
appear to be more sensitive to chocolate. Chocolate provides a mood boost to women during
PMS and menstruation, when serotonin levels are often down.
Probably the most influential love compound in chocolate is PEA. This chemical, which
occurs in chocolate in small quantities, stimulates the nervous system and triggers the
release of pleasurable opium-like compounds endorphins. PEA also potentiates the activity
of dopamine, a neurochemical directly associated with sexual arousal and pleasure. PEA acts
as a potent antidepressant in both genders and rises during periods of romance. The giddy,
restless feelings that occur when we are in love are because of PEA to an extent, as it is
significantly increased in the brain at that time and when we achieve orgasm. Some
scientists dismiss this notion, claiming that the PEA in chocolate is metabolized too quickly
to produce a significant mood-altering effect, but others disagree. Why else would chocolate
be so inextricably intertwined with love and romance?
Activities for students to demonstrate the love chemistry
oxytocin – allow students to give friends hugs if the friend agrees
pheromones – allow students to try on some cologne or perfume with pheromones
adrenaline – who thinks they are in love? Have students test with “love meter” (a hand
boiler)
PEA – give them each a piece of dark chocolate because it has PEA
Valentine gifts
Love Apples – In olden days, women would put a peeled apple under their armpit and allow
it to soak up pheromones. When a loved one went to war, the women gave the apple to
the man so they could smell them.
Synthetic diamonds – Companies can make diamonds out of breath or ashes of loved ones.
Flowers – Buy white flowers. Spray them with phenolphthalein (don’t tell students). Show
them the flowers, and share with them that you really want pink flowers. Spray with a
basic solution (ex: 6 M ammonia), and they turn pink.
Relationship demos
Potassium permanganate demo – blind date – slow to start and then sparks fly
Gun cotton – quick fling and then it’s over
Thionin (demo from Flinn Scientific) – sometimes people are different around the one
they date and their everyday friends
Minute-to-win-it
Stack candy hearts – Put 15-20 in each bag and have students get in groups of twos.
Measure the height in cm for each group. They can eat the hearts after.
Juju hearts – I draw four names from each class for this activity. I
have lids to party pail ice cream that have a nice blue circle ring.
Students bite of the tips of the hearts and make a circle and see who gets the
furthest around in one minute.
Marshmallow toss – One partner has a plastic cup and the other stands on the
other side of the room and tries to throw marshmallows into the cup.