CHMC Syllabus for Class - Seminole State College of Florida
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Both 12C and 13C are stable isotopes. The nuclei of some isotopes are unstable and decay spontaneously, emitting particles and energy. When 14C decays, one of its neutrons is converted to a proton and an electron.
This converts 14C to 14N, transforming the atom to a different element. Radioactive isotopes have many applications in biological research. Radioactive decay rates can be used to date fossils. Radioactive isotopes can be used to trace atoms through metabolic processes.
Radioactive isotopes are also used to diagnose medical disorders. For example, a known quantity of a substance labeled with a radioactive isotope can be injected into the blood, and its rate of excretion in the urine can be measured. Also, radioactive tracers can be used with imaging instruments to monitor chemical processes in the body.
While useful in research and medicine, the energy emitted in radioactive decay is hazardous to life. This energy can destroy molecules within living cells. The severity of damage depends on the type and amount of radiation that the organism absorbs.
Electron configuration influences the chemical behavior of an atom.
Question about ionic and covalent bonds?
Simplified models of the atom greatly distort the atom's relative dimensions. To gain an accurate perspective of the relative proportions of an atom, if the nucleus was the size of a golf ball, the electrons would be moving about 1 kilometer from the nucleus. Atoms are mostly empty space. When two elements interact during a chemical reaction, it is actually their electrons that are involved. The nuclei do not come close enough to interact.
The electrons of an atom vary in the amount of energy they possess. Energy is the ability to do work. Potential energy is the energy that matter stores because of its position or location.
Water stored behind a dam has potential energy that can be used to do work turning electric generators. Because potential energy has been expended, the water stores less energy at the bottom of the dam than it did in the reservoir. Electrons have potential energy because of their position relative to the nucleus.
The negatively charged electrons are attracted to the positively charged nucleus. The farther electrons are from the nucleus, the more potential energy they have.
Changes in an electron's potential energy can only occur in steps of a fixed amount, moving the electron to a fixed location relative to the nucleus. An electron cannot exist between these fixed locations. The different states of potential energy that the electrons of an atom can have are called energy levels or electron shells. The first shell, closest to the nucleus, has the lowest potential energy. Electrons in outer shells have more potential energy.
Electrons can change their position only if they absorb or release a quantity of energy that matches the difference in potential energy between the two levels.
The chemical behavior of an atom is determined by its electron configuration-the distribution of electrons in its electron shells.
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The first 18 elements, including those most important in biological processes, can be arranged in 8 columns and 3 rows. Elements in the same row fill the same shells with electrons. Moving from left to right, each element adds one electron and proton from the element before.
The first electron shell can hold only 2 electrons. The two electrons of helium fill the first shell. Atoms with more than two electrons must place the extra electrons in higher shells. For example, lithium, with three electrons, has two in the first shell and one in the second shell.
The second shell can hold up to 8 electrons. Neon, with 10 total electrons, has two in the first shell and eight in the second, filling both shells. The chemical behavior of an atom depends mostly on the number of electrons in its outermost shell, the valence shell.
Electrons in the valence shell are known as valence electrons. Lithium has one valence electron; neon has eight. Atoms with the same number of valence electrons have similar chemical behaviors. An atom with a completed valence shell, like neon, is nonreactive.
All other atoms are chemically reactive because they have incomplete valence shells. The paths of electrons are often portrayed as concentric paths, like planets orbiting the sun.
In reality, an electron occupies a more complex three-dimensional space, an orbital. Each orbital can hold a maximum of two electrons. The first shell has room for a single spherical 1s orbital for its pair of electrons.
The second shell can pack pairs of electrons into a spherical 2s orbital and three dumbbell-shaped 2p orbitals. The reactivity of atoms arises from the presence of unpaired electrons in one or more orbitals of their valence shells.
Electrons occupy separate orbitals within the valence shell until forced to share orbitals. The four valence electrons of carbon each occupy separate orbitals, but the five valence electrons of nitrogen are distributed into three unshared orbitals and one shared orbital. When atoms interact to complete their valence shells, it is the unpaired electrons that are involved. These interactions typically result in the atoms remaining close together, held by attractions called chemical bonds.
The strongest chemical bonds are covalent bonds and ionic bonds. A covalent bond is formed by the sharing of a pair of valence electrons by two atoms. If two atoms come close enough that their unshared orbitals overlap, they will share their newly paired electrons. Each atom can count both electrons toward its goal of filling the valence shell. For example, if two hydrogen atoms come close enough that their 1s orbitals overlap, then they can share a pair of electrons, with each atom contributing one.
Two or more atoms held together by covalent bonds constitute a molecule. We can abbreviate the structure of the molecule by substituting a line for each pair of shared electrons, drawing the structural formula. H-H is the structural formula for the covalent bond between two hydrogen atoms. The molecular formula indicates the number and types of atoms present in a single molecule. H2 is the molecular formula for hydrogen gas.
Oxygen needs to add 2 electrons to the 6 already present to complete its valence shell. Two oxygen atoms can form a molecule by sharing two pairs of valence electrons. These atoms have formed a double covalent bond. Every atom has a characteristic total number of covalent bonds that it can form, equal to the number of unpaired electrons in the outermost shell.
This bonding capacity is called the atom's valence. The valence of hydrogen is 1. Phosphorus should have a valence of 3, based on its three unpaired electrons, but in biological molecules it generally has a valence of 5, forming three single covalent bonds and one double bond. Covalent bonds can form between atoms of the same element or atoms of different elements. While both types are molecules, the latter are also compounds. Water, H2O, is a compound in which two hydrogen atoms form single covalent bonds with an oxygen atom.
This satisfies the valences of both elements.
Methane, CH4, satisfies the valences of both C and H. The attraction of an atom for the shared electrons of a covalent bond is called its electronegativity. Strongly electronegative atoms attempt to pull the shared electrons toward themselves. If electrons in a covalent bond are shared equally, then this is a nonpolar covalent bond.
A covalent bond between two atoms of the same element is always nonpolar. A covalent bond between atoms that have similar electronegativities is also nonpolar.
Because carbon and hydrogen do not differ greatly in electronegativities, the bonds of CH4 are nonpolar.
When two atoms that differ in electronegativity bond, they do not share the electron pair equally and form a polar covalent bond. The bonds between oxygen and hydrogen in water are polar covalent because oxygen has a much higher electronegativity than does hydrogen. Compounds with a polar covalent bond have regions of partial negative charge near the strongly electronegative atom and regions of partial positive charge near the weakly electronegative atom.
An ionic bond can form if two atoms are so unequal in their attraction for valence electrons that one atom strips an electron completely from the other. For example, sodium, with one valence electron in its third shell, transfers this electron to chlorine, with 7 valence electrons in its third shell. Now, sodium has a full valence shell the second and chlorine has a full valence shell the third.
After the transfer, both atoms are no longer neutral, but have charges and are called ions. Sodium has one more proton than electrons and has a net positive charge. Atoms with positive charges are cations. Chlorine has one more electron than protons and has a net negative charge. Atoms with negative charges are anions. Because of differences in charge, cations and anions are attracted to each other to form an ionic bond. Atoms in an ionic bond need not have acquired their charges by transferring electrons with each other.
Compounds formed by ionic bonds are ionic compounds, or salts. An example is NaCl, or table salt. The formula for an ionic compound indicates the ratio of elements in a crystal of that salt.
Ionic compounds can have ratios of elements different from 1: For example, the ionic compound magnesium chloride MgCl2 has 2 chloride atoms per magnesium atom. Magnesium needs to lose 2 electrons to drop to a full outer shell; each chlorine atom needs to gain 1. Entire molecules that have full electrical charges are also called ions. The lab experiments are designed to be safe if the instructions are followed.
Since they involve chemicals, heat and other potentially harmful things, serious injuries could result if the safety guidelines are not followed. Failure to observe these precautions will result in eviction for the remainder of the class period and a grade of zero for all corresponding lab work.
What are the basic rules for lab conduct? If you are late and miss these, the instructor may not allow you to do the lab because you have missed these important instructions and it is not the responsibility of the instructor to repeat material due to your tardiness.
No food or drink in lab. Do not touch, taste or smell any chemicals in the lab. Wash your hands whenever you leave the lab to prevent accidental ingestion or contact with chemicals. Indirect vented safety goggles the only acceptable type are worn at all appropriate times in the lab, including when you are washing your hands in preparation to leave the lab. The only acceptable times to not be wearing your safety goggles is when you first walk into the lab and when you are walking out at the end of the lab.
Cotton or wool pants must cover you to the ankle. No shorts, yoga tights, leggings, skirts, capri pants or dresses allowed. Sandals, ballet flats without sockspumps, etc. Shoes must also be low-heeled and provide good traction.
Clothing made from natural fibers cotton, wool, linen is recommended. Long hair must be pulled back and secured. Do not do unauthorized experiments. Clean up your mess. How is safety enforced in the lab? For your first minor violation, you receive a warning.
For your second, you will be docked 20 points. For your third, you will be banned from lab for the duration of the semester and receive a score of 0 for all remaining labs.
For a major safety violation you will be banned from lab for the duration of the semester and receive a score of 0 for all remaining labs. An example of a minor violation is not wearing your goggles at all times.
Examples of major violations are having a water bottle on the lab bench, doing an unauthorized experiment or not cleaning up spilled chemicals. This is solely the discretion of the instructor, however. If I have a medical condition should I inform the instructor?
If you have a condition such as heart problems or epilepsy and you do not wear a medical information bracelet, please let your instructor know. This will allow the instructor to provide emergency responders with information that may be critical to your future health should you be unable to speak for yourself. If you are pregnant, please inform the instructor for the reason listed above. The instructor can also keep you informed of any additional safety precautions you may want to consider.
Finally, if you have color blindness, please let the instructor know. Many labs require descriptions of colors. Lab Protocols How do I prepare for labs? Go to the course website and print out the documents required for that lab day. Note that due to the restructuring of the course, not all lab procedures will be available on the first day of classes.
You will need to be diligent; Read the lab procedures; Complete any pre-lab questions if that lab has one. They must be completed and turned in by the start of the lab — no late pre-labs will be accepted; Dress appropriately; Bring a pen — all data in lab must be recorded in ink or there will be points deducted. How do I record data in the lab? All data in the lab must be recorded in ink in the correct place on the correct sheets as you take it.
You may not write it on a separate piece of paper and then copy it over to your data sheet. No credit is given for labs with ANY data written in pencil. You get a 0 for that lab. What if I write down something incorrect? Any errors should be crossed-out with a single line. No credit will be given for labs if white-out is used. These rules are not optional. This ensures that you have followed the rules.
Failure to get approval means no credit for the lab and it is your responsibility to get approval. How can I get full credit for each lab? Full credit is given only for reports turned in on time that have all data recorded properly, all calculations done as instructed, all results are accurate and any lab questions fully answered correctly.
Yes — part of your grade depends on the accuracy of your experimental results. Poor results are an indication of sloppy work.
When are lab reports due? Due dates are listed clearly in the course schedule but generally labs are due the week following the lab experiment. The labs are due by the end of the class period or they are considered late. What if I turn in a lab report late? Late labs will have 1 point deducted for each weekday day they are late; reports more than one week late will receive no credit. Late labs may be turned in via email as a single pdf no other formats accepted to bakerw seminolestate.
What if we have multiple labs due on the same day? Each outline and lab report must be handed in separately — do not staple them together.
Do I have to pay for broken glassware or damaged equipment?