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Atomic Structure II: Isotopes and the Periodic Table

Atomic Structure II: Isotopes and the Periodic Table. Objective: 1. Students will learn Chemical Symbolism. 2. Students will also learn that elements are classified by chemical and physical properties. Standards used:

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Atomic Structure II: Isotopes and the Periodic Table

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  1. Atomic Structure II:Isotopes and the Periodic Table Objective: 1. Students will learn Chemical Symbolism. 2. Students will also learn that elements are classified by chemical and physical properties. Standards used: 5.2.8.A.4 Predict the physical and chemical properties of elements based on their positions on the Periodic Table.

  2. Prerequisite Review:Model of an atom What is the Contemporary Nuclear Model? The Contemporary Nuclear Model depicts a nucleus surrounded by the most likely regions that electrons are likely to inhabit. What comprises the nucleus? The nucleus is composed of protons and neutrons. Protons are positively charged; Neutrons have no charge. Are all atoms alike? Daltons’ Theory states that atoms belong to different elements have different properties. Oxygen atoms are not the same as Carbon atoms.

  3. What defines an element? The atoms of different elements are distinguished by the number of protons in their nuclei.

  4. Ways of Classifying Elements Atomic number- number of protons in an atom’s nucleusAtomic mass- number of protons and neutrons in an atom’s nucleus. Isotope- same atomic number but different atomic mass

  5. Comparison of an atom and its isotopes For hydrogen and its isotopes: deuterium and tritium, the nucleus always contains 1 proton, but the number of neutrons changes: 1 neutron for deuterium, and 2 neutrons for tritium.

  6. Using the definitions of Atomic Number and Atomic Mass, determine the Atomic number and Atomic mass for Hydrogen, Deuterium, and Tritium Hydrogen: contains 1 proton and 0 neutrons Atomic number is 1,Atomic Mass is 1+0=1 Deuterium: contains 1 proton and 1 neutron Atomic number is 1, Atomicmass is 1+1=2 Tritium: contains 1 proton and 2 neutrons Atomic number is 1, Atomic mass is 1+2=3

  7. History of the Periodic TableOrganizing Elements into a meaningful pattern. Between 1827 and 1819, Johann Dobereiner organized elements according to chemical properties. 1862, A.E.Beguyer de Chancourtoisorganized elements according to increasing atomic mass due to the observation that chemical properties appeared in periodic intervals. John Newland postulated that Chemical properties repeated in intervals of eight.

  8. Mendeleev (1834 -1907) Arranged elements according to chemical properties and periodic intervals of 17 elements. (Modern Periodic Table has intervals of 18 elements). Although Mendeleev’s table contained errors and he arranged elements according to Atomic mass as opposed to Atomic Number (to be done by Henry Mosely), he left gaps in his Table for the existence of future elements.

  9. Mendeleev’s Table Modern Table

  10. Physical Classification of Elements: Metals, Nonmetals, and Metalloids Metals are colored blue Nonmetals are colored yellow Metalloids are colored purple. Each column, or Group(1A, 7B, 4A, etc..), contains elements with similar chemical properties. Each row is called a period.

  11. Interpreting Chemical Symbols 126C C- represents name of element (carbon) 6- representsAtomic Number (6 protons) 12- represents Atomic Mass (6 protons + 6 neutrons)

  12. Metals Metals are malleable (change shape without breaking), good conductors of heat and electricity, and they are lustrous (shiny). Copper-used for electrical wiring Aluminum foil-great for wrapping up hot food

  13. Nonmetals Nonmetals have variable shapes (brittle solids, hard solids, liquids, gases), are poor conductors of electricity and heat, and have a dull luster. Two nonmetals, one is solid, the other liquid. What a difference in physical appearance!!

  14. Metalloids Metalloids exhibit properties intermediate between those of metals and non-metalloids, may also conduct electricity at high temperatures (semi-conductors). Ge (Germanum) -used for AM Radio signals. As (Arsenic)- used for Rat Poison It doesn’t look shiny like Ge

  15. Lesson Review Define Atomic Number, Atomic Mass, Isotope. Atomic Number represents the number of protons in the nucleus of an atom. Atomic Mass represents the number of protons and neutrons in the nucleus of an atom. Isotopes have the same of protons but different number of neutrons. How are elements arranged on the periodic table? Elements are arranged by similar chemical properties (Groups) in order of increasing Atomic Number.

  16. Lesson Review continued What are the three physical categories of elements? Elements are divided into metals, nonmetals, and metalloids.

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