2.2a Fundamentals of Chemistry
Summary
TLDRIn this module on physiology, the instructor explains why understanding chemistry is crucial for grasping bodily functions. The lesson covers the composition of the human body by elements, emphasizing key ones like oxygen, carbon, hydrogen, and nitrogen. It introduces basic atomic structure, explaining protons, neutrons, and electrons, with a focus on electron shells and valence electrons, which determine how atoms bond. The periodic table is discussed, highlighting the importance of elements like calcium and sodium in physiological processes. The lesson wraps up with a quick quiz on valence electrons for various elements.
Takeaways
- š§Ŗ The module starts with the basics of chemistry because understanding the chemical properties of molecules and elements is essential for learning about physiology.
- š Oxygen is the most abundant element in the human body, making up nearly two-thirds of its composition, followed by carbon, hydrogen, and nitrogen.
- āļø Elements are the simplest units of matter and cannot be broken down into smaller parts under normal circumstances (excluding nuclear fusion).
- š§¬ Atoms combine to form compounds, which are substances made up of two or more elements joined through chemical bonds.
- š¬ Atoms consist of protons (positive charge), neutrons (neutral charge), and electrons (negative charge), with protons and neutrons forming the nucleus.
- āļø The periodic table includes key information such as the atomic number (number of protons, neutrons, and electrons) and atomic weight (mass of one mole).
- š Electrons orbit the nucleus in specific regions called electron shells, and the outermost shell (valence shell) determines how an atom bonds with others.
- š Valence electrons, located in the outermost shell, play a crucial role in bonding properties, as seen in the sodium atom example.
- š” A quick overview of elements and their valence electrons includes examples such as hydrogen (1 valence electron), helium (2), carbon (4), and neon (8).
- š Elements like calcium and iron will be essential to discussions throughout the semester, with calcium being particularly significant in the course.
Q & A
Why is chemistry important in a physiology class?
-Many physiological processes in the human body are determined by the chemical properties of molecules and elements, making it essential to understand chemistry before diving into these processes.
What are the most abundant elements in the human body?
-Oxygen, carbon, hydrogen, and nitrogen are the most abundant elements in the human body, with oxygen making up nearly two-thirds of all elements.
What are trace elements, and what is their role?
-Trace elements, such as boron, chromium, and copper, exist in small amounts but play important roles as catalysts for chemical reactions in the body.
What is an element, and why is it important in chemistry?
-An element is the simplest unit of matter that cannot be broken down into smaller parts. It is important in chemistry because elements combine to form compounds, which are the basis of chemical reactions.
What is the difference between an atom and an element?
-An element is a type of matter, while an atom is the smallest quantity of that element which retains its unique properties.
What are the three types of atomic particles that make up an atom?
-Atoms are made up of protons (positive charge), neutrons (neutral charge), and electrons (negative charge).
What is the significance of the atomic number on the periodic table?
-The atomic number represents the number of protons in an element, and it also corresponds to the number of electrons in a neutral atom.
What is an electron shell, and why is it important in bonding?
-An electron shell is a layer of electrons surrounding an atomās nucleus at distinct energy levels. The arrangement of electrons in these shells, particularly in the outermost shell (valence electrons), determines how an element bonds with others.
What is valency, and why is it important in chemistry?
-Valency refers to the number of electrons in the outermost electron shell of an atom, which determines how that atom can bond with other atoms.
How can we determine the number of valence electrons for elements like hydrogen, helium, carbon, and neon?
-For hydrogen, there is one valence electron. Helium has two, filling its first shell. Carbon has four valence electrons, and neon has eight, filling its second shell.
Outlines
š§Ŗ Introduction to Chemistry for Physiology
The speaker begins by addressing why chemistry is important in a physiology course, explaining that understanding molecular and elemental interactions is crucial for grasping physiological processes. The human body's composition is highlighted, with oxygen, carbon, hydrogen, and nitrogen being key elements, followed by inorganic elements like calcium and phosphorus. Trace elements, like boron and fluorine, serve as catalysts in reactions. The concept of elements as the smallest unit of matter is introduced, with a note on exceptions such as nuclear fusion. The transition into compounds, formed by chemical bonds between elements, sets the stage for further exploration of atomic structure.
š§¬ Understanding Atoms and Atomic Structure
The discussion continues by defining an atom as the smallest quantity of an element, retaining its unique properties. The structure of atoms is explored, explaining that atoms consist of protons (positive charge), neutrons (neutral charge), and electrons (negative charge). The planetary model of the atom is introduced, using helium as an example with two protons and two neutrons in the nucleus. The focus shifts to the periodic table, specifically carbon, explaining the atomic number (number of protons, neutrons, and electrons) and atomic weight. The concept of a mole in chemistry is briefly reviewed, followed by an introduction to valency, the electron configuration determining how atoms bond.
āļø Electron Shells and Bonding Properties
The third section delves deeper into electron shells, which dictate how atoms bond with others. A crash course on electron shells is presented, explaining that the first shell holds two electrons, the second holds eight, and the third shell begins to fill after that. Sodium is used as an example with 11 electrons, filling the first two shells and leaving one valence electron in the third. The valence electron's role in determining bonding properties is emphasized. The section concludes by reviewing four elements (hydrogen, helium, carbon, neon) and identifying their valence electrons based on their atomic structure.
Mindmap
Keywords
š”Element
š”Atom
š”Proton
š”Neutron
š”Electron
š”Valence Electron
š”Periodic Table
š”Atomic Number
š”Electron Shell
š”Molecule
Highlights
Introduction to the fundamentals of chemistry in a physiology class.
The chemical properties of molecules and elements influence physiological processes in the human body.
The human body is primarily composed of oxygen, followed by carbon, hydrogen, and nitrogen.
Inorganic elements such as calcium, phosphorus, and potassium play crucial roles in physiology.
Trace elements like boron, chromium, cobalt, and copper act as catalysts for chemical reactions.
Elements are the simplest unit of matter, with some exceptions due to nuclear fusion.
Atoms are made up of protons (positive), neutrons (neutral), and electrons (negative).
Protons and neutrons are located in the nucleus, while electrons orbit in shells around it.
The periodic table shows the atomic number and atomic weight, with a focus on up to calcium for the course.
A mole equals 6.02 x 10^23 atoms, an important concept in chemistry.
Electron shells determine how atoms bond, focusing on outer shell electrons (valence electrons).
Valency is a key concept in determining how atoms bond with others.
The first electron shell holds two electrons, the second can hold eight.
Sodium's electron configuration with 11 electrons is an example of how valency works.
Examples of valence electrons for elements: hydrogen (1), helium (2), carbon (4), and neon (8).
Transcripts
Welcome back folks. So in this module we're goingĀ to start off with the fundamentals of chemistry.Ā Ā
So some of you might be asking, "Okay this isĀ a physiology class ā why do we have to get intoĀ Ā
chemistry?" Well it turns out many of the processesĀ in the human body are determined by the chemicalĀ Ā
properties of those molecules and elements,Ā so it makes sense ā before we jump into anyĀ Ā
serious physiology processes, we have to learnĀ about how these atoms and elements interactĀ Ā
at the molecular level. So let's go ahead andĀ start off with the composition of the human body.Ā Ā
So as you can see on your screenĀ right here, specifically at the table,Ā Ā
you can see what percentage each elementĀ makes up in the human body. So some of theĀ Ā
most relevant ones that we'll be discussingĀ throughout the whole entire semester includeĀ Ā
oxygen, which makes up nearly two-thirds of allĀ elements in the human body and that's followed byĀ Ā
carbon, which makes about 1/6 of the total elementsĀ in the body. We also have a notable amount ofĀ Ā
hydrogen and nitrogen, followed by some inorganicĀ elements such as calcium, phosphorus, and potassium.Ā Ā
So at the bottom of the table you'll noticeĀ that there will be some trace elements such asĀ Ā
boron, chromium, cobalt, copper, fluorine, etc. and soĀ these are largely there as catalysts for chemicalĀ Ā
reactions to occur. So when I say "element", this isĀ the simplest unit of matter that cannot be brokenĀ Ā
down into smaller parts. There's an asterisk thereĀ just because there are some technicalities to thisĀ Ā
such as nuclear fusion but we won't really jumpĀ into much detail about that. So for all intentsĀ Ā
and purposes, elements are, for us, the smallestĀ unit of matter. So in nature, elements rarely occurĀ Ā
by themselves but instead they've combined to formĀ compounds. And so we define compounds as substancesĀ Ā
composed of two or more elements joined throughĀ chemical bonds and what we'll see in a momentĀ Ā
is that the chemical properties of each elementĀ determines what type of bonds can be formed byĀ Ā
that element. So diving right in, let's go ahead andĀ review what an atom is and what is it made up of.Ā Ā
So an atom is defined as the smallest quantity ofĀ an element that retains unique properties of thatĀ Ā
element. So put in another way, an atom of hydrogenĀ is considered the smallest unit of hydrogen thatĀ Ā
can exist. As you might be able to guess, atoms areĀ unfathomably small. So these atoms are composed ofĀ Ā
even smaller atomic particles and there's threeĀ types. So we have protons, which have a positiveĀ Ā
charge, neutrons which have a neutral charge, andĀ electrons that have a negative charge. And as youĀ Ā
can see on our helium model, right here ā so noticeĀ in the planetary model there is a nucleus in theĀ Ā
center and surrounding it are electrons within theĀ nucleus. You can see it's made up of two protonsĀ Ā
and two neutrons. So since we're going to beĀ talking about all these different elements, I thinkĀ Ā
it's worth reviewing some of the key points ofĀ the periodic table of elements. So let's go aheadĀ Ā
and use carbon as an example. So carbon is theĀ sixth element on the periodic table of elementsĀ Ā
and there are two particular numbers that I thinkĀ you should be aware of. So the first one is thisĀ Ā
number, the atomic number, and it indicates theĀ number of protons neutrons and electrons for thatĀ Ā
atom. Next you'll notice that there is this numberĀ right here, which corresponds to the atomic weightĀ Ā
or the mass in one mole of carbon. AndĀ so just a quick review from chemistryĀ Ā
a mole is equal to 6.02 times 10 toĀ the 23rd atoms and so for this classĀ Ā
ā and so for this class, you should be aware ā soĀ for this course you should be generally awareĀ Ā
of the chemical properties of these elements...Ā about up to calcium. We're actually going to beĀ Ā
talking about calcium quite a bit in this course.Ā Some other elements that might be past calciumĀ Ā
include iron, when we talk about hemoglobin butĀ that's not quite as important as everything beforeĀ Ā
our 20th element calcium. So when talking aboutĀ elements it's important to focus on the electronsĀ Ā
since they determine how an element can bondĀ to other elements. So unlike some of the imagesĀ Ā
of atoms that I've shown on the previous screenĀ and the one that you see of sodium right here,Ā Ā
electrons don't actually orbit the nucleus inĀ a perfect circle instead they stay within theseĀ Ā
particular regions of space called electron shells.Ā And an electron shell is a layer of electronsĀ Ā
that surround the nucleus at distinctĀ energy levels and we call this valencyĀ Ā
and this valency determines how that atom can bondĀ with other atoms. And I just want to point out thatĀ Ā
specifically it's electrons that occupy soĀ ā specifically it's electrons that occupy the outerĀ Ā
electron shell. So we're going to do a veryĀ quick crash course on electron shells. If youĀ Ā
need a little bit more in-depth explanation aboutĀ this, you could take a look at the video that I amĀ Ā
linking in the upper right corner. Otherwise, let'sĀ go ahead and start with this quick explanation.Ā Ā
So like I said before, electron shells canĀ accommodate a certain number of electrons and eachĀ Ā
electron shell has space for a specific number ofĀ electrons. So in the first layer that we see here,Ā Ā
we see that the first electron shell canĀ accommodate two electrons. After that, we moveĀ Ā
on to the next electron shell. So our secondĀ electron shell, which can accommodate eightĀ Ā
electrons ā after all those eight electrons occupyĀ the second shell, then we move on to our thirdĀ Ā
and as we can see there's only one electronĀ occupying that third electron shell. And thisĀ Ā
corresponds to the atomic number of sodium, 11,Ā which which means that there are 11 electrons. WeĀ Ā
have two in the first shell we have eight in theĀ second shell and then one more to get that numberĀ Ā
11. So this outermost electron is what we call aĀ valence electron, because it occupies the outermostĀ Ā
shell and it determines the bonding propertiesĀ of our sodium ion, which we'll discuss when weĀ Ā
talk about ionic bonding. So based on what we'veĀ just learned, we have four different elements hereĀ Ā
starting with the one right here, we have hydrogen,Ā helium, carbon, and neon. So for each of theseĀ Ā
go ahead and answer the question of, "How manyĀ valence electrons do each of these elementsĀ Ā
have?" Okay and so for hydrogen this one's easyĀ since we're on the first shell we have one singleĀ Ā
electron, which is our valence electron so it'sĀ one. And helium, the second atomic element has twoĀ Ā
electrons, so those two electrons will fill theĀ first electron shell ā so we have a valency of two.Ā Ā
For carbon, which is our sixth element, thoseĀ first two electrons will occupy that first shellĀ Ā
and then the next four electrons will occupy thatĀ second shell which gives us a valency of four.Ā Ā
And then neon the tenth element has two ā its firstĀ two electrons occupy that first electron shell andĀ Ā
then the remaining eight will occupy its outermostĀ shell so we have eight valence electrons here.
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