nucleus contains positively charged protons and uncharged neutrons. The electron cloud is composed of negatively charged electrons. Elements in the same row are similar in size. Elements in the same column have similar electronic and chemical properties. An s orbital has a sphere of electron density and is lower in energy than the other orbitals of the same shell. A p orbital has a dumbbell shape and contains a node of electron density at the nucleus. It is higher in energy than an s orbital.
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29 years. What fraction of the atoms in a sample of 90Sr would remain 175 years later? Answer 0.166 0.125 0.062 here 0.015 Which relation is not correct? Answer 11p = 11H = proton 0-1e = 0-1β = electron here +10e = +10β= positron 10n = neutron As a result of beta decay‚ the product nucleus is Answer one atomic number lower than the original element. two atomic number higher than the original element. here one atomic number
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Lesson 03.01: History of the Periodic Table Explain how scientific observations led to the development of‚ and changes to‚ the periodic table. Russian chemist Dmitri Mendeleev set out to organize the 63 known elements according to their properties. Mendeleev wrote the name‚ mass‚ and chemical properties of each element on a separate card and arranged the cards by various properties‚ looking for trends and patterns. When he arranged the elements by increasing atomic mass‚ Mendeleev noticed that similar
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of variation of mass with speed and mass energy equivalence. 12. A proton of rest mass [pic] is moving with a velocity of 0.9c. Calculate its mass and momentum. TUTORIAL SHEET: 1 (Module1: Special Theory of Relativity) . 13. The speed of an electron is doubled from 0.2 c to 0.4 c. By what ratio does its momentum increase? 14. A
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another Covalent Bonding - two atoms each sharing electrons within a molecular orbital Metallic Bonding - positive metal ions held together in a lattice with a “sea of electrons” An actual chemical bond is a blend of all three types of bonding. Most often‚ one type is dominant over others. We will concentrate on ionic and covalent bonding. LEWIS STRUCTURES Only valence electrons are important in bonding. Lewis dot structures show valence electrons surrounding atom. We visualize the four valence orbitals
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absolute configuration absolute counting in radioanalytical chemistry absolute electrode potential absolute full energy peak efficiency absolute lethal concentration ( )quantity absolute lethal dose ( )quantity absolute photopeak efficiency absolute preconcentration in trace analysis absorbance‚ quantity absorbance matching in spectrochemical analysis absorbed dose of a substance absorbed dose‚ of radiation absorbed electron coefficient in in situ microanalysis absorbed electrons in in
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based on total external reflectivity. Using this method we can calculate the thickness of the film electron density profile of the material and roughness of the film surface. After a short introduction of Fresnel’s reflectivity‚ the Parratt formulation is used for the calculation reflectivity for a stratified film. Then after discussing the experimental technique‚ we have calculated the thickness‚ electron density and roughness from the experimental curve. CONTENTS Introduction---------------
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0 Points Question 1 of 23 2.0/ 2.0 Points How many core electrons are in a chlorine atom? A.10 B.7 C.17 D.1 E.none of the above Answer Key: A Question 2 of 23 2.0/ 2.0 Points Which subshell letter corresponds to a spherical orbital? A.f B.d C.p D.s E.not enough information Answer Key: D Question 3 of 23 2.0/ 2.0 Points Consider the electron configuration of the ion to determine which ion shown below has an incorrect
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The different electron energy levels caused in hydrogen cause these lines in the spectrum to be produced in this way because the wavelengths that are released when the electron move back to the ground state is specific and it varies accordingly. 2. Into which energy level are electrons dropping into to make these visible lines? The electrons are dropping back to the ground state which is the bottom most energy level to makes these visible lines. 3. What happens when the electrons drop into the
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of Radiation and Radioactivity Introduction: Radiation can be defined as the propagation of energy through matter or space. It can be in the form of electromagnetic waves or energetic particles. Ionizing radiation has the ability to knock an electron from an atom‚ i.e. to ionize. Examples of ionizing radiation include: • alpha particles • beta particles • neutrons • gamma rays • x-rays Non-ionizing radiation does not have enough energy to ionize atoms in the material it interacts with. Examples
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