the six elements of life
speech transcript
Liceo Classico L. Ariosto – Ferrara
CHNOPS
the six elements of life
in accordo con il
Ministero dell’Istruzione, Università, Ricerca
e sulla base delle
Politiche Linguistiche della Commissione Europea
percorso formativo a carattere
tematico-linguistico-didattico-metodologico
scuola secondaria di secondo grado
teacher
Maria Petresi
eniscuola / smartenglish – A cura di Linda Rossi Holden
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Label europeo 2010
the six elements of life
CHNOPS: the Six Elements of Life
Teacher: Hello everybody, today I will give a lecture on CHNOPS, the six elements of
life. Let's start with the observation of this table that shows the biological
macromolecules we studied last year. The four major macromolecules found in living
things are: carbohydrates, lipids, proteins and nucleic acids. They're made of smaller,
repeating sub units called monomers; their name are amino acids for proteins,
monosaccharides for carbohydrates, nucleotides for nucleic acids….
Matteo: …No teacher! Today’s lesson will be done by us.
Students: Yeah!! Let's go!
Matteo: Today we are going to discuss CHNOPS.
Federica: What are CHNOPS?
Matteo: CHNOPS are the six elements of life. CHNOPS means: carbon, hydrogen,
nitrogen, oxygen, phosphorous and sulfur.
They are important because the elements in life are about 25, but these six are the
most common in living organisms. They are the ingredients of life.
All these elements are non-metals.
Teresa: But, where can we find the other elements?
Matteo: We can find oxygen, silicium, aluminum and iron in the earth’s crust, and
hydrogen, helium, oxygen, carbon, neon, nitrose, magnesium, silicium, iron and
sulphur in the Universe.
A curiosity, we can tell that we are like bacteria. Indeed, euchariots and prochariots
have a similar percentage of CHNOPS.
Nicolò: What’s the most important element?
Matteo: The carbon, because it’s the only that makes a very huge quantity of
biological macromolecules.
Maria Luce: What’s the carbon?
Ilaria: I have the answer! The carbon is an element, solid at room temperature; it’s a
non-metal which we identify with the symbol C, belongs to the fourth group and to the
second period. It’s the base of the life and so every living being is composed of
carbon. So we can find it in Nature, in atmosphere (CO2) and in the Earth crust.
Giovanni: What about the structure of the carbon atom?
Ilaria: The atomic mass is 12 and the atomic number of carbon is 6. Now we’re going
to talk about hydrogen. Gianluca come here!
Gianluca: Hello everybody! Hydrogen it's a non-metal too.
It’s gas at room temperature. It’s an element apart. Its symbol is H. It belongs to the
first group and to the first period. And it’s the most common element in the Universe.
Hydrogen appears as H2, diatomic molecule.
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the six elements of life
Riccardo: Where can we find hydrogen, and what about its atomic structure?
Gianluca: Well, we can find it in a lot of composts, like water, hydrides, hydroxides
and acids and in organic compounds. Talking about its atomic structure, we can say
that its atomic number is 1 as its atomic mass.
Teresa: Excuse me, I haven’t understood what’s a non-metal. Can you help me?
Gianluca: Yes, of course. The non-metal are elements founded on the right zone of
the periodic table. They are usually gases, but in special conditions, they can be solid
or liquid. They don’t conduct electricity and neither heat.
Vassili: And now it's nitrogen time!
The nitrogen is a non-metal with symbol N. We can find it in the atmosphere; it’s a
gas at room temperature. It’s in every living thing too and it can form many
compounds to the oxygen and it's a diatomic molecule: N2.
Luca: Which is the atomic structure of the nitrogen?
Vassili: Oh yes, I was forgetting it!! Its atomic number is 7 and its atomic mass is 14.
Matteo: Okay, thank you!! Now we wanna talk about oxygen! Gaia come here.
Gaia: Yes! The oxygen, symbol O, belongs to the sixth group and second period. It's a
non-metal and it forms the 21% of the atmosphere gas form of a diatomic molecule.
Its atomic number is 8 and its atomic mass is 16.
Federica: Why it’s an element of life?
Gaia: Because without oxygen every aerobic organism would die. It allows the cellular
respiration and it’s produced by the photosynthesis. But the most important aspect is
that it's situated in all living things.
Giulia: Now let's start to explain phosphorus. This element is a non-metal like the
others. Its symbol is P. It’s solid at room temperature and it belongs to the fourth
group and third period.
Nicolò: Where can we find it in nature?
Giulia: The phosphorus appears as a calcium phosphate, in the animals skeletons
and in ATP nucleic acids as phosphate group. About the structure, its atomic number
is 15 and its atomic mass is 30. Ah, one more thing. It makes a single bond.
Francesco: Let’s start to talk about sulfur, symbol S. It's a non-metal solid at room
temperature. It belongs to the sixth group and the third period. Its atomic number is
16 and its atomic mass is 32.
Maria Luce: Can we find it in nature?
Francesco: Yes, we can find it in large deposits mainly in volcanic areas. You can also
find it in many minerals and in proteins.
Alessandro: Why these six specific elements?
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the six elements of life
Matteo: Because these elements share the characteristic of forming strong covalent
bonds. Among these, the carbon is the virtuous one. The CHNOPS build biomolecules
by joining atoms through these bonds.
Riccardo: Excuse me, what is a covalent bond? Can you explain it?
Matteo: Yes, covalent bond is a particular bond where the electrons are shared.
This bond depends on the number of the electrons in the outer shell.
The CHNOPS will share electrons with other elements, in order to complete its outer
shell and some elements, which are called noble gases, have their outer shells
complete and don’t have to share electrons.
Giovanni: Sorry, is there a way to represent the most important electrons in the
outer shell of an atom?
Giulia: Of course! It's the Lewis structure! Come here Ilaria, it's your turn!
Ilaria: Ok, here we go. Now I'll explain the Lewis structure. This is a representation of
the number of electrons that each atom has in the outer shell. The electrons are
represented by dots. These dots are founded in the 4 sides of the symbol of an atom.
Right Giulia?
Giulia: Oh yes. Francesco! Follow me and bring me the models of the CHNOPS?
Francesco: Yes.
Giulia: Thank you! Stay here! Ok, the ability of an atom to combine with other atoms
depends on the number of electrons in the outer shells of the atoms. Right?
Francesco: Yes. The number of covalent bonds that an atom can form is called
valence. Each element has a characteristic valence and we can see that in these
models.
Giulia: This is the carbon. You can see that it has 4 electrons and so it can form 4
bonds. It has valence 4. Then the hydrogen. It has 1 of valence.
Francesco: This is the oxygen, with 2 possible bonds, and the nitrogen, which has
valence 3.
Giulia: Now there are two particular examples. The first is the phosphorus, whose
molecule is formed by 4 phosphorus atoms, P4.
The phosphorus, as you can see, can make 5 bonds.
Francesco: The sulfur molecule instead, consists of 8 sulfur atoms, S8 and it has a
rhombic structure. The sulfur can have 3 types of valence. 2, 4 or 6.
Teacher: Well done! Thank you students!
Materiale sviluppato da eniscuola nell’ambito del protocollo d’intesa con il MIUR
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