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| Presec3.1 ...Area of Chemistry study that considers the quantities of materials consumed and produced in chemical reactions is called | Chemical Stoichiometry |
| sec3.1 A customer comes into a candy store and requests 1000 jelly beans. The jelly beans are each identical to each other and each has a mass of 5g . What mass of jelly beans would you be required to have in stock in order to satisfy this customers request? | 5 kg ....Each bean has 5g mass, need 1000 beans so 1000 beans times 5g each bean gives an overall needed mass of beans equal to 5 000 g , but since 1 000g = 1 kg, we need 5 kg in stock. |
| sec3.1 Total mass of objects DIVIDED by the total NUMBER of objects gives ? | AVERAGE mass.... Total sum of masses divided by sum of objects is Average Mass of each object...None of the individual objects neccessarily have to be equivalent to the average mass, in fact none may equal it.Average Mass is just that, an AVERAGE of all object masses in consideration. |
| sec3.1 Objects do NOT neccessarily have to hold identical masses to be counted by ? | Weighing...If one knows the AVERAGE Mass of the objects involve, one could divide the TOTAL MASSES of all the objects by the AVERAGE MASS of the objects to gain a great approximation to how many objects there are in the collection. |
| sec3.1 For purposes of COUNTING, the objects are viewed as if they behave as though they were all ? | Identical....For counting purposes, we need to VIEW that each object is exactly the AVERAGE MASS of the objects, although in reality we realize that some or even all the objects may NOT be that exact mass . |
| sec3.1 How do scientist determine the number of atoms in a given sample of substance? | By finding the substances MASS, we THEN can determine the number of objects of that substance. |
| sec3.2 Scientists John Dalton, Gay-Lussac, Avogadro , and Berzelius were the first to study and provide quantitative information about ? | Atomic Masses. ..The FIRST quantitative information about atomic masses came from works of Dalton, Lavoisier, Avogadro,Berzelius, and Guy-Lussac. |
| sec3.2 Nineteeth-century chemists calculated RELATIVE ATOMIC MASSES how? | By observation of the PROPORTIONS in which elements combine to form various compounds. |
| sec3.2 What year was the MODERN SYSTEM of ATOMIC MASSES instituted ? | In the year 1961 , it was based on the allowing C-12 (Carbon twelve, carbon with an atomic mass of 12) to be the STANDARD. |
| sec3.2 What isotope of what element is assigned a mass of exactly 12 atomic mass units (amu or u ), and the masses of all other atoms are given relative to this standard? | C-12 , Carbon Twelve...This is the Carbon isotope with 6 neutrons and an atomic mass of exactly 12 ( Recall atomic mass is the SUM of protons plus Neutrons)... Also written as such that the 12 is in the SUPERSCRIPT of the LEFTSIDE of the element carbon's sybol, such as 12^C with the 12 being a SUPERCRIPTED value. |
| sec3.2 Currently, what is the most accurate method to compare the masses of atoms. | Use of a Mass Spectrometer would ,TODAY, provide the most accurate method for comparing atomic masses. |
| sec3.2 In what instrument are atoms or molecules passed into a beam of high-speed electrons, which knock electrons off the atoms or molecules being analyzed and charge them into POSITIVE IONS. An applied field then ACCELERATES these ions into a magnetic field, causing an interaction between the ion and magnetic field occurs, the path of that ion tends to change. The AMOUNT OF PATH DEFLECTION for each differing ion DEPENDS on that ion's MASS.The most MASSIVE ions are deflected the LEAST amount, the least massive ions deflected the greatest.This change in ionic path causes ions of different masses to SEPARATE. What instrument facilitates this? | The Mass Spectrometer |
| sec3.2 An accelerating ion produces its own what? | Magnetic Field...Any accelerated charged object creates a magnetic field unique to itself |
| sec3.2 What is another commonly used name for Atomic Mass? | Atomic Weight |
| sec3.2 The atomic mass number for carbon based on the periodic table is 12.01 amu. Does this mean that there does exist at least one isotope of carbon that has the atomic mass number of 12.01 as well? | No--there is exactly NONE....No carbon nor any other isotope of any element that can be a fraction of a mass unit. The REAL atomic mass of any element's isotope MUST be a WHOLE NUMBER, irregardless of the element or isotope.Why? Because atomic mass number is the COUNTED SUN of Protons PLUS Neutrons, and you can NOT have a portion of a proton nor a portion of a neutron. |
| sec3.2 On Earth, what three(3) NATURAL carbon isotopes are found? | Natural Carbon, ON EARTH, is a mixture of three(3) carbon isotopes..The three(3) carbon isotopes making up natural earth carbon are C-12 , C-13 , and C-14. Since each isotope is from the element carbon, all three(3) always have exactly SIX(6) protons in its nucleus (no exceptions) but differ in the number of NEUTRONS each has. C-12 has 6 neutrons, C-13 has 7 neutrons, and C-14 has 8 neutrons. |
| sec3.2 What is the PERCENT COMPOSITION of natural carbon ( as found naturally on Earth) ? | caron (natural carbon from Earth) is made up of 98.89% C-12 atoms, 1.11% of C-13 atoms and a negligible amount of C-14 atoms. That is, since the amount of C-14 in natural carbon is so infinetly small it is virtually eliminated from calculation of percent compositions, so that virtually all the components of natural carbon comes from C-12 and C-13. |
| sec3.1 A commonly utilized AKA (also know as) for atomic mass number is? | average atomic mass |
| Because natural carbon ONLY consists of C-12, C-13, and a negligible amount of C-14 atoms, natural carbon does NOT contain a single atom with a mass of 12.01. However, we CONSIDER carbon to be composed of only one type of atom with a mass of 12.01 when? | For STOCHIOMETRY reasons we MUST calculate as if each atom of carbon possessed exactly 12.01 atomic mass although we KNOW that NO CARBON atom has that atomic mass. This enables scientists to COUNT atoms of natural carbon by WEIGHING a sample of carbon then dividing by the carbon's AVERAGE ATOMIC MASS of 12.01 |
| sec3.2 True or False? For any substance, counting by weighing will work if and only if you know the AVERAGE MASS of all the units being counted. | True--although there may or may not be any of the objects with that actual mass used as the average atomic mass. |
| sec3.2 Most elements occur in nature as mixtures of what? | Isotopes....Isotopes are atoms of the same element differing in ONLY the number of NEUTRONS each isotope has compared to the other isotopes of that element. All isotopes of a given element will always have the exact same number of PROTONS however...Essentially, the only difference between isotopes of the same element is in Atomic Masses, because the atomic numbers are all the exact same. |
| sec3.2 True or False? Atomic Masses are AVERAGE VALUES of all the element's isotopes' atomic masses. | True, the elemental atomic mass is an AVERAGED VALUE |
| sec3.2 What instrument is utilized to determine the isotopic composition of a natural element? | Mass Spectrometer...In addition to being useful in determining the accurate mass values for individual atoms, the mass spectrometer is used to determine the isotopic composition of a natural element. |
| sec3.2 According to collected scientific data, what occured about 250 million years ago in a cataclysmic event? | It is thought that approximately 90% if LIFE on earth was destroyed,marking the ending of the Permian Period and the start of the Triassic Period.This disaster to life on earth is considered the MOST DEVASTATING MASS EXTINCTION in all of earth's history. |
| sec3.2 What is the P-T boundary? | The P-T boundary is called the Permian-Triassic boundary, the intersection of two time periods in Earth's history. This boundary was about 250 million years ago and ended in 90% of Earth's living beings dying off because of a cataclysmic event. This boundary marks END of Periam Period and the beginning of the Traissic Period in earth's history. |
| sec3.2 It is thought by scientist that some 65 million years ago in earth's history what happened? | 65 million years ago a catastophic event occured wiping out the dinosaurs that dominiated earth's surface at that time. |
| sec3.2 Amongst other reasons, the discovery of a crater in the ocean near Mexico preceeded by discovery that the rocks from the time of the K-T boundry possessed an abnormally high concentration of iridium , it is believed that something from outter space caused the tremendous devastation ending the dinosaur presence on earth. What is this outter space object suspected to be? | An asteroid....Iridium is known to be moreso on asteroids than other outter space objects, thus the concentration being so high of iridium at that time's boundary with discovery of a probable crater location near Mexico in the ocean indicates the great likelihood that indeed it was a disaster caused by an asteroidal incident. |
| sec3.2 Another commonly used and accepted name for C-60 molecules , which are part of fullerene. | "buckyBalls" --- these are C-60 molecules whose cavities can trap other atoms such as helium and argon. |
| sec3.2 Where do scientist suspect that fullerenes originated? | In STARS or COLLAPSING GAS CLOUDS where noble gas atoms where trapped as the fullerenes were formed.The fullerenes were then somehow incorporated into the object that eventually hit earth. |
| sec3.2 Based on the isotopic compositions discovered, geochemist estimate that the impacting body that occured at the P-T boundary some 250 million years ago must have been how big? | Geochemist suggest the asteroidal impact at P-T boundary was comparable to the impact ending dinosaur life at the K-T boundary some 65 million years ago. That is, geochemist think the impacting asteroid was 10 kilometers in diameter.This is the prevailing thought today amongst geochemist despite the fact that there is a lack of iridium found in sediments from the P-T boundary as compared to that from the K-T boundary. |
| sec3.2 Although geochemist generally accept that the dinosauer era ended because of a asteroid impact, the overall lack of iridium discovered in the sediment from that time suggested the possibilitity that the impacting object may not have been an asteroid but rather a ? | COMET ...It is feasible that a comet impact could deliver such a blow to earth strong enough to intensify the volcanism already underway on earth, thus delivering what essentially is a "One-Two PUNCH" to earth, obliterating life on earth. |
