UCF CHM 2046 - Atomic Structure
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Topics Covered on Final Exam (70 questions; 2 hrs.)Atomic Structure: ground state electron configurationthe 4 quantum Numbers1. The principal quantum number (n) describes the size of the orbital. Orbitals for which n = 2 are larger than those for which n = 1, for example. Because they have opposite electrical charges, electrons are attracted to the nucleus of the atom. Energy musttherefore be absorbed to excite an electron from an orbital in which the electron is close to the nucleus (n = 1) into an orbital in which it is further from the nucleus (n = 2). The principal quantum number therefore indirectly describes the energy of an orbital.2. The angular quantum number (l) describes the shape of the orbital. Orbitals have shapes that are best described as spherical (l = 0), polar (l = 1), or cloverleaf (l = 2). They can even take on more complex shapes as the value of the angular quantum number becomes larger. 3. There is only one way in which a sphere (l = 0) can be oriented in space. Orbitals that have polar (l = 1) or cloverleaf (l = 2) shapes, however, can point in different directions. We therefore need a third quantum number, known as the magnetic quantum number (m), to describe the orientation in space of a particular orbital. (It is called the magnetic quantum number because the effect of different orientations of orbitals was first observed in the presence of a magnetic field.)electronic transition (no calculations)s, p, d orbitalsatom/ion symbols- Atomic number tells you protons-Isotopes & abundanceshttp://www.youtube.com/watch?v=-FZX1VQgsF0alphabetagamma decay in nuclear chemistry.Nuclear equations are typically written in the format shown below. There are 5 different types of radioactive decay.1. Alpha decay follows the form: Where A is the parent isotope (the atom being broken apart) B is the daughter isotope or the isotope formed. When an element is broken down in alpha decay it looses two neutrons and two (2) protons. This means that the name of the element will change as well, moving back two (2) places on the periodic table. Alpha decay is not very penetrating because the He atoms capture electrons before traveling very far. However it is very damaging because the alpha particles can knock atoms off of molecules. Alpha decay is the most common in elements with an atomic number greater than 83.2. Beta negative decay follows the form: The beta emission increases the atomic number by one (1) by adding one (1) proton. At the same time, one (1) neutron is lost so the mass of the daughter isotope is the same as the parent isotope. Beta negative decay is more penetrating than alpha decay because the particles are smaller, but less penetrating than gamma decay. Beta electrons can penetrate through about one (1) cm of flesh before they are brought to a halt because of electrostatic forces. Beta decay is most common in elements with a high neutron to proton ratio.3. Gamma decay follows the form: In gamma emission, neither the atomic number or the mass number is changed. A high energy gamma ray is given off when the parent isotope falls into a lower energy state. Gamma radiation is the most penetrating of all. These photons can pass through the body and cause damage by ionizing all the molecules in their way. 4. Positron emission (also called Beta positive decay) follows the form:In this reaction a positron is emitted. A positron is exactly like an electron in mass and charge force except with a positive charge. It is formed when a proton breaks into a neutron with mass and neutral charge and this positron with no mass and the positive charge. Positron emission is most common in lighter elements with a low neutron to proton ratio.5. Electron capture follows the form:In this reaction a nucleus captures one (1) of its own atom's inner shell electrons which reduces the atomic number by one. This captured electron joins with a proton in the nucleus to form a neutron. Electron capture is common in larger elements with a low neutron to proton ratio. Molecular Structure and Bonding: Hybridization: http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/hybrv18.swfsigma bonds and pi bonds1. A sigma bond is just a single bond. 2. When you have a double bond, you have 1 sigma bond and 1 pi bond. 3. When you have triple bond, you have 1 sigma bond and 2 pi bonds. How do pi bonds arise? First of all, only period 2 elements form pi bonds. This is due to the fact that period 2 elements are small in size and therefore form short bonds. Due to these short bonds, when 2 atoms like Carbon and Oxygen form a sigma bond, they are so close together, that an energy level(orbital) of carbon overlaps with an energy level(orbital) of oxygen. This forms a pi bond where electrons 'orbit' around.Ionic character in ionic solidsionic radiiNeutral atoms tend to increase in size down a group and across a period. When a neutral atom gains or loses an electron, creating an anion or cation, the atom's radius increases or decreases.band theorynaming simple compounds, Including transition metal compounds When elements from the far left of the periodic table (metals) react, they tend to loose electrons to form positive ions or cations. When elements from the right react with metals, they gobble up these electrons to form negative ions, or anions. Compounds formed between metals and nonmetals where this takes place are called ionic compounds and they are named from the ions that compose them. Cations formed from metals have the same name as the metal. If the metal can form more thanone different positive ion, the charge state of the metal is put in roman numerals within parenthesis following the metal name. Sometimes an older naming scheme is used: when only two ions can be formed from a given metal, an -ous ending is given to the Latin name of the metal for the lower charged (less positive) ion and and -ic ending is given for the higher chargedion. Cations formed from non-metals are given an -ium ending. Here are some examples of names of cations:Monoatomic anions are named by shortening the name of the element ad adding an -ide ending. Some simple polyatomic anions are also given the -ide ending (like hydroxide). Many polyatomic anions contain oxygen and these are called oxyanions. Usually, these anions come in groups that have the same charge but different numbers of oxygen atoms. The names of these species have the root derived from the non-oxygen atom, and the most common ion is given the

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# UCF CHM 2046 - Atomic Structure

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