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Published byHilary Chapman Modified over 8 years ago
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The Periodic Table trends
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History of the Periodic Table 1871 – Mendeleev arranged the elements according to: 1. Increasing atomic mass 2. Elements w/ similar properties were put in the same row. 1913 – Moseley arranged the elements according to: 1. Increasing atomic number 2. Elements w/ similar properties were put in the same column.
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Increasing energy 1s 2s 3s 4s 5s 6s 7s 2p 3p 4p 5p 6p 3d 4d 5d 7p 6d 4f 5f Review of Electron Configuration
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Periodic Table & Electron Configuration
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Periodic Groups Elements in the same column have similar chemical and physical properties. These similarities are observed because elements in a column have similar e - configurations (same amount of electrons in outermost shell).
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Know the Group Names
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Periodic Trends Trends we’ll be looking at: 1.Atomic Radius and Ionic Radius 2.Ionization Energy 3.Electronegativity 4.Reactivity 5.Metallic Character
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Atomic Radius Atomic Radius – size of an atom (distance from nucleus to outermost e - ).
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Atomic Radius Trend Group Trend – As you go down a column, atomic radius increases. As you go down, e - are filled into orbitals (energy levels) that are farther away from the nucleus (attraction not as strong). Periodic Trend – As you go across a period (L to R), atomic radius decreases. As you go L to R, e - are put into the same energy level, but more p + and e - total (more attraction = smaller size).
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Ionic Radius Ionic Radius - size of an atom when it is an ion.
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Ionic Radius Trend Metals – lose e -, which means more p + than e - (more attraction) SO… Ionic Radius < Neutral Atomic Radius Nonmetals – gain e -, which means more e - than p + (not as much attraction) SO… Ionic Radius > Neutral Atomic Radius
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Ionic Radius Trend Group Trend – As you go down a column, atomic radius increases. Periodic Trend – As you go across a period (L to R), atomic radius decreases.
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Ionization Energy Ionization Energy – energy needed to remove outermost e -.
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Ionization Energy Group Trend – As you go down a column, ionization energy decreases. As you go down, atomic size is increasing (less attraction), so easier to remove an e -. Periodic Trend – As you go across a period (L to R), ionization energy increases. As you go L to R, atomic size is decreasing (more attraction), so more difficult to remove an e - (also, metals want to lose e -, but nonmetals do not).
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How do electron configurations explain why there is a big change in energy at the red line? Energy to Take Off Several Electrons
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Electronegativity Electronegativity- tendency of an atom to attract e -.
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Electronegativity Trend (really electron affinity) Group Trend – As you go down a column, electron affinity decreases. As you go down, atomic size is increasing, so less attraction of electrons to the nucleus. Periodic Trend – As you go across a period (L to R), electron affinity increases. As you go L to R, atomic size is decreasing, so the electrons are more attracted to the nucleus.
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Reactivity Reactivity – tendency of an atom to react. Metals – lose e - when they react, so metals’ reactivity is based on lowest Ionization Energy (bottom/left corner) – Low I.E = High Reactivity. Nonmetals – gain e - when they react, so nonmetals’ reactivity is based on high electronegativity (upper/right corner). – High electronegativity = High reactivity
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Metallic Character Properties of a Metal – – Easy to shape (malleable); many are ductile (can be pulled into wires) – Conduct electricity and heat – Shiny Group Trend – As you go down a column, metallic character increases (because ionization energy decreases). Periodic Trend – As you go across a period (L to R), metallic character decreases (because ionization energy decreases) (L to R, you are going from metals to non- metals).
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Do This… Based on these trends, can you describe some properties of the following groups? Alkali Alkaline Halogens Noble Gases – Also, be able to identify metals, transition metals semi- metals, and non-metals and know some properties of each.
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