chemlecture.notebook
September 24, 2013
QOD Ch 2­
Outline #1
9/23/13
1. What is the most common element in the body by mass/weight?
2. What is an ion?
3. How many bonds can Carbon form?
Sep 30­2:33 PM
GENERAL CHEMISTRY: CHAPTER 2
Describe the structure of an atom:
Smallest stable unit of matter
Atom Neg (­) charge, outside nucleus in energy levels, negligible mass, determines chemical characteristics
Electrons Pos charge (+), in nucleus, mass of 1 AMU, determines physical characteristics Protons
No charge, in nucleus, similar in mass to proton Neutrons
Sep 12­5:30 PM
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chemlecture.notebook
September 24, 2013
What is the difference between the atomic number and the mass number?
Atomic #: number of protons/electron in neutral atom
Mass #: protons + neutrons
Isotope: Atom w/ different mass number than normal, can be radioactive­ often used in medical diagnostics
Ion: occurs when an atom or compound loses or gains an electron, therefore becoming charged.
Sep 17­12:03 PM
Elements: pure substance, one kind of atom, displayed on Periodic Table
List of the most common elements in the body­ p. 28
CHEMICAL BONDS Why do atoms form bonds with other atoms?
Different atoms join in order to achieve stability (fill their outermost shell w/electrons)
This electrical compatibility is known as BONDING
Compounds: a chemical substance made up of 2 or more different types of atoms
Molecules: atoms held together by covalent bonds
Sep 19­12:34 PM
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Periodic Table is in back of text p. A­39
Sep 22­2:09 PM
Reactive elements
Non­reactive elements
Sep 22­2:11 PM
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chemlecture.notebook
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Describe the formation of an ionic bond:
Ionic bonding: occurs between ions (charged atoms or molecules)
1. electron donor loses e­ becomes cation (+)
2. electron acceptor gains e­ becomes anion (­)
3. attraction between opposites draws ions together
Not particularly stable, dissolves in water
Sep 12­5:30 PM
Sep 19­1:41 PM
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chemlecture.notebook
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http://www.youtube.com/watch?v=lODqdhxDtHM&feature=related
Aug 30­7:47 AM
Describe the formation of a covalent bond:
Another form of bonding is due to a sharing of electrons known as COVALENT BONDING
Electrons travel so fast between atoms, that outer shells seem "full" all of the time
Can occur as:
Single bonds H­H H2
or double bonds O=O O
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O=C=O CO2
or even triple bonds!
Covalent bonds are usually: STRONG, STABLE­most bonds found in living tissues
http://www.youtube.com/watch?v=j1e­f1W­0UA&feature=related
Sep 19­12:47 PM
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chemlecture.notebook
September 24, 2013
Free radical: unpaired electrons
Sep 19­1:42 PM
What is the difference between non­polar covalent bonds and polar covalent bonds?
Polar covalent bond
Sep 19­1:42 PM
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chemlecture.notebook
September 24, 2013
What is the importance of hydrogen bonding in biological systems?
There are a few other weak forces that act between atoms and molecules­
Most important: Hydrogen Bonds
The attraction between the + and the ­ end of a polar covalent bond
Too weak to create molecules, but can change shapes, or pull molecules together/apart
Example: surface tension of water
Sep 19­1:01 PM
Exit Task: Complete the Atomic Number and Mass Number Review If you don't finish today, complete as HW
Remember­
The atomic # = # of protons and # of electrons The mass # is the # of protons + the # of neutrons
An ion will have more or less electrons than a neutral atom
An isotope will have a different # of neutrons
If it is a neutral atom, leave last column blank­ or write neutral
Periodic Table is also in back of text p. A­39 Due tomorrow
Oct 3­12:56 PM
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