Articles+for+Close+Reads+and+Text+Based+Questions+in+Science

Conrad Schools of Science NGSS Articles (pulled from UD/Lib Search) from March 28th Professional Development Physics (By John Castellaneta) - **//[|Astronomy and Cosmology: Pre-Eighteenth Century] //** Summary and analysis of developments in Physics and Astronomy during and after the Scientific Revolution. Emphasis on particular physicists' contributions and cosmological models. Biology (By Dana Hammaker and Kathleen Caligiuri) - //**[|Transgenic Plants]**// --> Summary of the potentials of GMOs AND [|Biopharming] --> AN outline of the new production methods of plant-made pharmaceuticals. Biomedical Science (By Rob Naylor) - //**[|Arthritis]**// This article is for a high school Biomed/Anatomy course. If you are responsible for a unit on joints, or range of motion, this is a great article for an extension on those topics. Discussing why some individuals lose the full range of motion as a result of various types of arthritis. Aquatic Biology (By Josh Farside) - //**[|Sustaining Resilience at Sea]**// Summary of the state of Marine Reserves

Mr. Field - Cab Calloway School of Arts
Source: trends on periodic table [] and then go to periodic table trends, then select the first document in the list.


 * periodic trends **
 * From: ** //Encyclopedia of Physical Science//.

The periodictable of the elements is a visual representation of the atomic structure of the known chemical elements. The table is arranged in order of increasing atomic number, with elements having the same number of valence electrons found in the same column or group, and elements with valence electrons in the same energy level found in the same row or period. Periodictrends become evident when the chemical and physical properties of the elements vary according to their position on the periodictable. Types of periodictrends that can be determined by an element's position on the periodictable include atomic mass, atomic radii, ionic radii, density, ionization energy, electronegativity, and electron affinity. Each of these properties contributes to the chemical reactivity of the element.

The arrangements of the elements on the earliest versions of the periodictable depended on increasing atomic mass, and then in 1914 a British chemist named Henry Moseley rearranged the table and based his arrangement on atomic number. The current model of the table shows that most elements follow the trend of increasing atomic number across the periods from left to right and down the groups from top to bottom. Exceptions include cobalt and nickel, tellerium and iodine, and several of the newly discovered elements. In general, the periodic trend is that the atomic mass of the element increases with the atomic number. Many of the periodictrends of elements result from the shielding effect of the electrons. Every nucleus exerts a positive attraction, called the effective nuclear charge, for the electrons of the atom. The existence of electrons positioned between the nucleus and the energy level of the electron in question weakens the force of this attraction. The electrons located in the inner energy levels, between the electrons in the outer shells and the nucleus, block the force of the protons' attraction; simply put, they get in the way. This phenomenon is known as electron shielding, and it reduces the hold of the protons on the outer electrons. The shielding effect increases when more energy levels are present in the atom. The repulsive forces between electrons in the same energy level have a similar shielding effect, although not as strong as that of the electrons in lower energy levels. Atomic radius is a measure of the size of the atom, and for metals it is one-half the distance between two nuclei in a diatomic molecule. The atomic radius indicates the distance of the valence electrons from the nucleus. The hold on electrons located farther away from the nucleus is weaker, so the distance from the nucleus to the outside of the atom or the outer energy level plays an important role in determining chemical characteristics of an element. The periodic trend of atomic radii increases in a group from top to bottom. As one moves down the group, the elements at each step have one more energy level than the elements in the previous (higher) row, and, therefore, the atomic radius increases. One might expect the atomic radius of the elements to increase across a period as well, but that is not the case—the atomic radius decreases across a period. Increasing the number of electrons in an outer energy level (as one moves from left to right across a period) does not increase the overall size of the atom. The elements across the period have more protons and electrons, and the addition of more protons gives the positively charged nucleus a stronger attractive force for the electrons in the outer energy level with the same relative amount of shielding from lower-energy-level electrons. Those electrons are held more closely than the electrons of an element in an equivalent energy level and with fewer protons, explaining why the atomic radii decrease from left to right within a period. The ionic radius of an element is the radius of a cation or an anion. When an element gains an electron and becomes an anion, the radius of the anion is larger than that of the original atom. This is because the atom and ion have the same number of protons and, therefore, the same effective nuclear charge, but the ion now has one more electron that will increase the repulsion between the electrons and make the outer shell larger. When an element loses an electron and becomes a cation, the radius of the ion is smaller than that of the original atom because the cation contains one less electron but has the same effective nuclear charge. This causes the electrons of the cation to be pulled more tightly toward the nucleus. While the ionic radius varies across the periods of the periodictable, both anions and cations increase their ionic radius as one progresses down a group. The ionic radius increases with the increased number of energy levels added to the atom, just as atomic radius does. When the ionic radius is compared for different elements across a period, it is necessary to compare elements that contain the same number of electrons. When a cation and an anion contain the same number of electrons, the cation will always have the smaller ionic radius because it has the higher number of protons, thus a higher effective nuclear charge. The density of an element is defined as the mass of an atom of the element divided by the volume the atom occupies. For some elements, the density can be determined by their location on the periodictable. The density of the nonmetals decreases significantly and the density of the gases and noble gases drops off the charts, with the result that the least dense elements are located on the right side of the periodictable. The ionization energy of an atom is the amount of energy required to remove an electron from the neutral atom in its gaseous state and to form an ion. The ionization energy must be measured in the gaseous state of the atom to avoid any intermolecular forces between neighboring atoms. Ionization energy is measured in units of kilojoules per mole. The tighter the hold a nucleus has on a valence electron, the harder it is to remove that electron from the element, and therefore the ionization energy will be greater. The ionization energy varies across the periods, increasing from left to right. If the elements are in the same period, then one can predict the ionization energy of the elements relative to one another. Elements on the right side of the periodictable have the highest ionization energy, meaning energy must be supplied in order to remove an electron. These elements have a higher effective nuclear charge and a smaller atomic radius than atoms to their left, and, therefore, they hold their electrons more tightly than atoms with the same number of energy levels and fewer protons. Because the atomic radii are smaller, the elements on the right of the table require more energy input to remove one of their electrons. Fluorine, with nine protons, being shielded by only two inner shell electrons, holds onto its outer electrons more tightly than lithium, with only three protons being shielded by its two inner shell electrons. The noble gases have the highest ionization energies of all of the elements on the periodictable, and helium has the highest first ionization energy. The high ionization energy of nonmetals explains why they become anions when they ionize. The ionization energy decreases down the groups of the periodictable. The farther down the table, the more energy levels shielding the nucleus from the valence electrons, and the harder it is for the protons to hold onto the valence electrons. The very low ionization energies of the alkali metals allow them to donate an electron readily. This periodic property explains why metals form cations when they ionize. If an element is able to lose more than one electron, each electron lost has a characteristic ionization energy. The amount of energy required to remove the first electron is known as the first ionization energy, the energy required to remove the second electron is known as the second ionization energy, and so on. Once an atom loses its first electron, the amount of shielding due to the repulsion of the electrons is reduced, so the effective nuclear force of the protons increases and the remaining electrons are held more tightly. This means that the second ionization energy is higher than the first, and the third ionization energy is higher than the second. Electronegativity is the measure of the attraction of an atom for the electrons shared in a covalent bond. If an atom has a very high electronegativity, it is highly attracted to shared electrons and is likely to "hog" the electrons when forming a bond. The difference in electronegativity between the two elements involved in the bond determines whether they form ionic or covalent compounds. In 1932, the American chemist Linus Pauling developed a measurement system for electronegativities that gives the most electronegative element on the periodictable, fluorine, a value of 4, and lithium, which is located to the far left in the same period on the table , is given a Pauling value of 1. The least electronegative element on the periodictable has a Pauling value of 0.7. If the electronegativity difference between the two atoms involved in a bond is high enough, the more electronegative element can "steal" the electron from the less electronegative element, and an ionic bond will form. An electronegativity difference that is greater than or equal to 1.7 means an ionic bond will form. If the difference is between 1.4 and 0.4, a polar covalent bond will form. An electronegativity difference of less than 0.2 will create a true covalent bond where the bonding electrons are equally shared between the two elements. The electronegativity of an atom is dependent on the effective nuclear charge, related to its number of protons. If the element is able to hold on tightly to its own electrons, that same nuclear charge will be able to hold additional electrons gained by forming a covalent bond closely to that atom. Electronegativity increases from left to right across the periodictable. The elements in a period essentially have the same shielding but with an increased nuclear charge as one moves across the table. Electronegativity values decrease as one proceeds down a group on the periodictable. The shielding caused by the increased number of energy levels of electrons causes the elements farther down the group not to have enough of a nuclear charge to attract the bonded electrons. The decrease down the group of electronegativity helps explain the difference in elemental properties on groups of the periodictable. Some groups, or families, contain nonmetal, metalloid, and metal elements. This is due to the fact that as more energy levels are added, the atoms lose their ability to attract bonded electrons. Electron affinity is the attraction that an element has for additional electrons, a periodic property closely related to ionization energy. While the ionization energy is the amount of energy required to remove an electron from a neutral atom, electron affinity indicates the likelihood of an atom to take on another electron. In order to measure electron affinity, one measures the amount of energy required to remove an electron from the ionized gaseous state of the atom. The difference between this and measuring the first ionization energy is that here electrons are being removed from an ion rather than a neutral atom. A large, positive electron affinity means that a lot of energy is required to remove the electron from the ionized state, so that atom must have a high affinity for the extra electron. The harder it is to remove the extra electron from the ion, the higher the atom's affinity for that electron. The variation of electron affinity down the groups is relatively small. All of the elements in a group have the same valence electron configuration, and so they exhibit a similar tendency to accept more electrons. The halogens have the highest electron affinities of all of the groups on the periodictable because they have seven valence electrons and the acceptance of one more electron gives them the same stable electron configuration as that of the next noble gas. The electron affinities of the noble gases are near 0. Because the noble gases already have a full octet of valence electrons, they have no inclination to take on another electron. All metals including the alkali metals (Group IA) and alkaline earth metals (Group IIA) have electron affinities lower than those of the nonmetals. Text-dependent questions: Thought question. ..
 * 1) What are the periodic trends that can be determined by an element’s position on the periodic table?
 * 2) Why does the atomic radius get larger when you go from top to bottom of the periodic table?
 * 3) Why does the atomic radius get smaller as you go from left to right on the periodic table?
 * 4) What is the relationship between the electronegativity, ionization energy, and electron affinity trends on the periodic table?
 * 1) Given the trends for ionization energy and electronegativity-, which element in this list is more likely to give up a valence (outer) electron to a neighboring atom? (K, Al, S, Cl)

John Mester, Stanton Middle



Clark Moncure, A.I. DuPont High



Michael Page, A.I. DuPont High

[|Natural Selection]

Barbara Farmer, Skyline Middle

Title: What Will Happen After Sun Vaporizes Earth? Scorched Planets Hold Clue Source: Christian Science Monitor Publication Date: Dec 20, 2011 Page Number: n.p. Database: SIRS Issues Researcher

"Scientists say they've found two planets that survived being swallowed by a red-giant star. Earth won't be so fortunate when our sun becomes a red giant in 5 billion years, but the find shows what can happen to solar systems after such dramatic events....The planets are a glimpse at what can happen to a solar system when a star begins its death throes, becoming bloated and red as it consumes the last of the hydrogen fuel in its core. The same fate awaits our sun in about 5 billion years." (Christian Science Monitor) This article postulates what could happen to Earth--and the rest of the solar system--in the wake of the sun's final red-giant phase.

Christian Science Monitor Dec 20, 2011, n.p.

Copyright © 2011 The Christian Science Monitor ([|www.CSMonitor.com]). Limited printing and electronic copying is permitted under this license agreement. Copies are for personal use only. For re-use and publication permissions, please contact copyright@csps.com. What Will Happen After Sun Vaporizes Earth? Scorched Planets Hold Clue By Pete Spotts Scientists say they've found two planets that survived being swallowed by a red-giant star. Earth won't be so fortunate when our sun becomes a red giant in 5 billion years, but the find shows what can happen to solar systems after such dramatic events.

Forget this season's final episode of "Survivor." The ultimate survivors appear to be two small planet-candidates engulfed for a billion years inside the searing envelope of a red-giant star. And they emerged to tell the tale.

The planets are a glimpse at what can happen to a solar system when a star begins its death throes, becoming bloated and red as it consumes the last of the hydrogen fuel in its core. The same fate awaits our sun in about 5 billion years.

The two planet-candidates announced Tuesday are among the tiniest yet revealed by data from NASA's planet-hunting Kepler spacecraft. And they hold the potential to shed light not only on how planets could survive such a torching, but also how they might affect the evolution of red-giant stars themselves.

"On many levels, it's very cool," says Elizabeth Green, a researcher with the University of Arizona's Steward Observatory and a member of the team reporting its observations in the Dec. 22 issue of the journal Nature.

A red giant originates as a star roughly like our sun - between 0.5 and 8 times the sun's mass. As the star exhausts its hydrogen fuel, its core collapses. The heat of that event causes remaining hydrogen in the outer shell to begin fusion, and the star's outer layer, or photosphere, expands.

By the time the red-giant phase of our sun ends, the Earth, Venus, and Mercury are likely to be vaporized. But scientists have examples of other objects - planets and brown-dwarf stars - that survived being enveloped by red-giant stars they orbited.

None of them, however, is like the ones reported Tuesday. All the previous examples were bigger objects that orbited farther from their parent stars to begin with. For that reason, they didn't spiral as deeply into their stars' photospheres. When these stars' red-giant phase ended - and the stars shrank back to become helium-burning so-called subdwarf B stars - the planets survived.

By contrast, the objects reported Tuesday appear to have traveled far deeper into the red-giant's photosphere and survived only as tiny remnants.

Indeed, the planet-candidates orbit so close to their subdwarf B star, named KIC 05807616, that their years are 5.8 hours and 8.2 hours long, respectively. With one side constantly facing the star, the planets' sun-side faces would roast at between 14,000 and 16,000 degrees Fahrenheit.

So how did the planet-candidates survive such a blistering? The team suggests that the objects may represent the rocky cores of stripped-down gas-giant planets that once orbited farther away.

As KIC 05807616 went through its red-giant phase and expanded, the two planets had to push through far more material as they orbited, creating a drag that slowed them down. That began a long spiral toward the star's core, and as the gas-giant planets migrated, they were stripped of their gas until only the rocky cores remained.

In the process, however, these planets also could have hastened the end of the star's red-giant phase, the team suggests.

The star's gravity is at its weakest in the outer reaches of the extended photosphere. As the planets migrated, their gravity could have stirred the star's outer photosphere in ways that stripped the hot gas away.

There are other possible explanations for the planet-candidates' presence. They could have been rocky planets to start with, were destroyed, and when the red-giant phase ended and the star's photosphere contracted, they reformed from the torched leftovers, says Eliza Kempton, a scientist at the University of California at Santa Cruz, who focuses her research on small extrasolar planets and was not part of the team.

Ironically, the team, which was led by French astronomer Stephane Charpinet of the University of Toulouse, didn't set out to hunt for planets, Dr. Green explains. Instead, the scientists were using Kepler's data to study stars - in particular, stars that had passed through their red-giant phase and had begun to burn the helium in their cores.

KIC 05807616 is one such star. Like many stars, KIC 05807616 varies in brightness in repeating patterns. These patterns can yield information on a star's mass, temperature, size, even the structure of its interior.

Kepler measures such changes with high precision because of the requirements of its planet-hunting mission. It hunts for extrasolar planets by measuring how a planet slightly dims a star's light when passing in front of it. But the scientists using its data need to be able to separate planet-induced dimming from a host star's built-in swings in brightness.

As Dr. Charpinet's team analyzed the varying brightness patterns from KIC 05807616, they detected two additional sets that didn't mesh with the patterns from the star itself.

After carefully weighing other explanations, the most probable explanation left standing was the presence of two planets.

Not everyone is convinced that the team has detected planets, with some ready to go no farther than to describe planet patters as "intriguing modulations." And while the team is confident that the objects are planets, they still formally dub them planet-candidates.

Whatever the answer, astrophysicists studying stars are as tickled to have Kepler on orbit as are planet-hunters. Compared with the tools available prior to Kepler's launch, the quality of the data pouring in from the mission "is fantastic," Green says.

Citation (MLA) :

Spotts, Pete. "What Will Happen After Sun Vaporizes Earth? Scorched Planets Hold Clue." Christian Science Monitor. 20 Dec. 2011: n.p. SIRS Issues Researcher. Web. 28 Mar. 2014.

Citation (APA) :

Spotts, P. (2011, Dec 20). What will happen after sun vaporizes earth? scorched planets hold clue. Christian Science Monitor. Retrieved from []

Kim Fanny, Cab Calloway School of Arts

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Christopher Meanor, A.I. DuPont High

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Physics topics:

[|Kinematics]

[|Forces]

[|Momentum/Impulse]

[|Circular motion]

[|Electricity]

[|Wave Motion]

[|Sound]

[|Light]

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Susan Aylor, Stanton Middle School

Scientists find more to study as Milky Way's portrait gets larger
<span style="color: #333333; font-family: ronnia_ltlight; font-size: 17.33px;">By **<span style="font-family: ronnia_ltlight;">Milwaukee Journal Sentinel, adapted by Newsela staff ** <span style="color: #333333; font-family: "Helvetica","sans-serif";"> <span class="imagecaption" style="color: #333333; font-family: "Helvetica","sans-serif";">The Milky Way arches over Monument Valley near the Arizona-Utah state line. <span style="color: #333333; font-family: "Helvetica","sans-serif";">Photo: <span class="imagecredit" style="color: #333333; font-family: "Helvetica","sans-serif";">Wally Pacholka/NASA <span style="color: #333333; font-family: "Helvetica","sans-serif";">MILWAUKEE — A team of Wisconsin scientists has stitched together an exciting 360-degree view of the Milky Way. This remarkable new view shows our spiral-shaped galaxy from every direction. <span style="color: #333333; font-family: "Helvetica","sans-serif";">Galaxies are groups of stars held together by gravity. In addition to the millions of stars in a galaxy, there are the planets, gasses and space dust in between them. Earth is located in the Milky Way Galaxy, one of many galaxies that makes up our universe. <span style="color: #333333; font-family: "Helvetica","sans-serif";">The new picture of our galaxy, which was unveiled on Thursday, is known as GLIMPSE360. It is made up of about 2.5 million images collected by NASA’s Spitzer Space Telescope. This orbiting telescope has been mapping the galaxy for more than 10 years.
 * <span style="color: #333333; font-family: ronnia_ltlight; font-size: 17.33px;">03.26.14 **<span style="color: #333333; font-family: ronnia_ltlight; font-size: 17.33px;"> midnight

Meet Spitzer
<span style="color: #333333; font-family: "Helvetica","sans-serif";">Spitzer is an infrared telescope. That is, it records things as they appear in infrared light. This allows scientists who study space — called astronomers — to see much that isn't visible in ordinary light. Infrared telescopes can cut through clouds of interstellar dust that block visibility with ordinary telescopes. <span style="color: #333333; font-family: "Helvetica","sans-serif";">Thanks to Spitzer, astronomers have been able to study much that was previously hidden in the Milky Way. More than 200 million new stars have been identified. <span style="color: #333333; font-family: "Helvetica","sans-serif";">And now thanks to GLIMPSE360, scientists can easily examine the structure of the Milky Way. It has parts that extend out like arms in a spiral shape. Scientists can now see how many spiraling arms it has, where they are and how far out they extend. <span style="color: #333333; font-family: "Helvetica","sans-serif";">But GLIMPSE360 isn't only about the big picture. Viewers can also zero in on particular objects by using a zoom feature.

A Band Of Millions Of Stars
<span style="color: #333333; font-family: "Helvetica","sans-serif";">GLIMPSE360's infrared images prove something scientists had suspected: A structure shaped like a bar runs like a straight line through the center of the Milky Way. This structure consists of millions of stars and extends out to about 12,000 to 13,000 light years from the galaxy’s center. One light year alone equals around 6 trillion miles. <span style="color: #333333; font-family: "Helvetica","sans-serif";">And GLIMPSE360 can help scientists in a lot of other ways as well. <span style="color: #333333; font-family: "Helvetica","sans-serif";">“We can see stars being born," astronomer Edward Churchwell said. "And if we can identify stars in the process of forming, we can start to learn" more about "how stars are formed. We don’t really understand the details of how stars are born.” <span style="color: #333333; font-family: "Helvetica","sans-serif";">Scientists also now may be able to figure out where stars are formed. <span style="color: #333333; font-family: "Helvetica","sans-serif";">Scientist Robert Benjamin says they can now see every region that forms stars in the galaxy. <span style="color: #333333; font-family: "Helvetica","sans-serif";">And the new view gives scientists some idea how quickly the Milky Way grows, said scientist Barb Whitney. “It tells us how many stars are forming each year.”

Astronomers Have Plenty To Study
<span style="color: #333333; font-family: "Helvetica","sans-serif";">The general location of stars in the galaxy is now visible. And astronomers expect to gain a deeper understanding of the dust that lies between the stars. <span style="color: #333333; font-family: "Helvetica","sans-serif";">But GLIMPSE360 also uncovers new puzzles to be solved. The infrared images show that the space between stars and planets, called interstellar space, is filled with patches of gas. <span style="color: #333333; font-family: "Helvetica","sans-serif";">“They are brightest around regions of star formation" but can be seen throughout the Milky Way, Churchwell said. "They’re floating out in the middle of interstellar space where they have no business being. It raises the question of how they were formed.” <span style="color: #333333; font-family: "Helvetica","sans-serif";">Sent into space in 2003, the Spitzer Space Telescope has far outlasted its planned two-and-a-half-year lifespan. The telescope remains in orbit, sending back infrared images. It can't last forever, however: It will eventually stop working once the liquid helium that cools its cameras runs out. <span style="color: #333333; font-family: "Helvetica","sans-serif";">More than 600 scientific papers already have been published using the information from Spitzer. <span style="color: #333333; font-family: "Helvetica","sans-serif";">Indeed, Spitzer has provided enough new information to keep astronomers busy for many years. “It’s done what we wanted it to do," Churchwell said.