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Questions About Atoms and Elements Chemistry 1.) The following statements are about the particles that make up the atom. For each statement write: p if it describes the proton e if it describes the electron n if it describes the neutron a.) The positively-charged particle ______ b.) Found with the proton, in the nucleus ______ c.) The particle that can occur in different numbers in atoms of the same element ______ d.) Held in shells around the nucleus. ______ e.) The negatively-charged particle. ______ f.) The particle with the negligible mass. ______ g.) The number of these particles is found by subtracting the proton number from the nucleon (mass) number. ______ h.) The particle with no charge. ______ i.) The particle with the same mass as a neutron. ______ j.) The particle that dictates the position of the element in the Periodic Table. ______ 2.) The atoms of an element can be represented by a set of three letters, as shown below. y zQ a.) What do the following letters stand for? i.) Q _____________________ ii.) y _____________________ iii.) z ____________________ b.) How many neutrons and protons are there in these atoms? i.) ii.) 107 47 Ag Neutrons _______ Protons ________ 63 29 Cu Neutrons _______ Protons ________ iii.) 1 1 iv.) 20 10 v.) 238 92 H Ne U Neutrons _______ Protons ________ Neutrons _______ Protons ________ Neutrons _______ Protons ________ c.) Most Bromine atoms have 45 neutrons. Describe a bromine atom, using the method in b.). _____ _____ ____ 3.) For each of the six elements aluminum (Al), boron (B), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S) fill in the table below: Element Period in Periodic Table Group Number in Periodic Table Proton (Atomic) Number Number of Number of electrons Electronic Outer in neutral configuration Shell atom electrons Al ______ ______ ______ ______ ________ ______ B ______ ______ ______ ______ ________ ______ N ______ ______ ______ ______ ________ ______ O ______ ______ ______ ______ ________ ______ P ______ ______ ______ ______ ________ ______ S ______ ______ ______ ______ ________ ______ 4.) Strontium, proton (atomic) number 38, is in the fifth period of the Periodic Table. It belongs to Group II. Complete the following. A neutral atom of strontium has: a.) how many electrons? ________________ b.) how many shells of electrons? _____________ c.) How many electrons in its outer shell? __________ 5.) Boron has two types of atoms, shown below. Proton Neutron Electron Atom A Atom B a.) What is different about these 2 atoms? b.) What name is given to atoms like these? c.) Describe each atom in shorthand form, as in problem 3.). _____ _____ ____ _____ _____ ____ d.) What is the nucleon (mass) number of atom A? ________ e.) Is Atom B heavier, or lighter, than Atom A? _________________ f.) Give the electron configuration for: Atom A _______________ Atom B _______________ g.) Do two isotopes of the same element have the same electron configuration? ________ 6.) The two metals sodium (proton (atomic) number 11) and magnesium (proton (atomic) number 12) are found next to each other in the Periodic Table. a.) State whether each phrase is the same, or different, for their atoms: i.) The number of electron shells. _________________ ii.) The number of outer (valent) electrons _____________ The relative atomic mass of sodium is 23.0. The relative atomic mass of magnesium is 24.3. b.) Which of the two elements may exist naturally as a single isotope? Justify your answer. 7.) This diagram represents the electronic arrangement for a neutral atom of an element. a.) Give the electron distribution for the atom. _______________ b.) What is special about this arrangement? ___________________________ c.) Which group of the Periodic Table does the element belong to? ________ d.) Name the element. ____________________ e.) Name another element with the same number of outer-shell electrons in its atoms. _______________________________ 8.) Gallium exists naturally as a mixture of two nonradioactive isotopes, gallium-69 and gallium-71. The proton (atomic ) number of gallium is 31. a.) i.) How many neutrons are there in gallium-69? ___________ ii.) How many neutrons are there in gallium-71? __________ Gallium also has a radioactive isotope, gallium-67. As gallium-67 decays, it gives out rays called gamma rays. b.) How does the radioactive isotope differ from the non-radioactive isotope? _______________________________________________________ c.) Name two possible uses, one medical and one non-medical, for gallium-67. _______________________________________________________ _______________________________________________________ 9.) From the following list of names: Aristotle Niels Bohr Boyle Chadwick Marie Currie John Dalton Democritus Proust Rutherford J. J. Thomson Identify the person most associated with each statement below. Some names will be used more than once. a.) ____________ Gold Foil Experiment b.) ____________ Concept of electron shells c.) ____________ Analyzed compression of gases, concluding that empty space predominated the volume. d.) ____________ In noticing the ratios of elements are always constant for a given compound, concluded elements must be composed of small, indivisible particles he called atoms. e.) ____________ Ancient Greek who proposed that matter can be broken down an infinite number of times and still maintain its properties. f.) _____________ Electrons exist in an atom. g.) ____________ Ancient Greek who proposed things are made of discrete units called atomos. h.) ____________ Cathode ray tube. i.) ____________ Atom composed of a nucleus containing positive charge. j.) _____________ Neutrons are also present in the nucleus of an atom. k.) ______________ Plum pudding model of an atom. l.) _______________ Investigated finding medical uses for radiation. m.) _______________ Recognized alpha particles, beta particles, and gamma rays. n.) ______________ Discovered elements polonium (Po) and radium (Ra). CHALLENGE PROBLEM 10.) In this problem we will estimate how likely it is that an alpha particle will strike the nucleus of a gold atom when passing through Rutherford’s gold foil, which was 0.00004 cm thick (4. x 10-7 m thick) We have mentioned that a typical atom has a radius of approximately 1 x 10-10 m. We will assume that a typical nucleus is about 1 x 10 -14 m (some references give a value of about 1 x 10-15 m, but in this problem let’s use 1 x 10-14 m). Gold atoms are arranged in a face centered cubic FCC arrangement, as shown in the diagram below: s r a.) What is the length of the diagonal of a face (in terms of r and in meters)? b.) What is the length, s, of a side of a face in meters? (show calculations) c.) What is the area of a face of the cube (in square meters)? d.) The cross section of how many nuclei are included on a face? s r e.) What is the total cross sectional area of the nuclei on the face? f.) What percent (as a decimal) of the face is a nucleus? g.) What is the reciprocal of part f.)? This gives how many alpha particles would pass through for every alpha particle that hits a nucleus. h.) How many atoms would line up over a thickness of 4.0 x 10-7 m? i.) Divide your answer in part g.) by that in part h.). This gives approximately how many alpha particles would pass through for every 1 that is deflected by a collision with a nucleus.