HOW ARE ELEMENTS ORGANIZED? (4-1) Periodic Table an arrangement of the elements in, based on a set of that repeat row after row

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1 The Periodic Table Chemistry, Ch. 3 HOW ARE ELEMENTS ORGANIZED? (4-1) Periodic Table an arrangement of the elements in, based on a set of that repeat row after row Dmitri Mendeleev created the first useful Inspired by solitaire! Mendeleev noticed properties of the elements formed a Was initially successful Mendeleev used it to existence of several new elements, and the properties of them But it wasn t perfect After the proton was discovered, they rearranged it by increasing (I.e. proton count) the periodicity became more perfect Periodic Law When the elements are arranged according to their, elements with similar properties appear at regular intervals Parts of the periodic table Periods the Groups the Sometimes called families Elements in the same groups have similar properties 3 Classes of Elements Metals Location: of the zig zag Properties: Good conductors of heat and electricity Malleable can be flat Ductile can be into a wire Shiny Usually solids 1

2 Nonmetals Location: To the of the zig-zag Properties: Poor conductors Not malleable Not ductile Dull Gases, liquids, and solids Metalloids Location: the zig-zag Properties: Partly like metals, partly like non-metals Ex. Are poor conductors at low temps and good conductors at high temps TOUR OF THE PERIODIC TABLE (4-2) We ll take a look a few key groups Alkali metals Alkaline Earth metals Transition metals F-block metals Halogens Noble Gases Hydrogen Alkali metals Group of periodic table Soft, silvery metals Ex. Na metal, flammable in water Alkaline-earth metals Group of periodic table Harder, denser than alkali metals Very reactive Ex. Ca metal, reacts vigorously with water Transition Metals Group of periodic table elements Most elements you might imagine when say metals are here Ex. gold, silver, chromium, copper, iron, etc. 2

3 F-block metals occur in the expanded section at the bottom of a standard periodic table Halogens Group elements Very reactive Ex. Fluorine, Chlorine, etc. Noble Gasses Group elements Ex. Helium, Neon, Krypton, etc. Hydrogen: Most common element in the universe of every atoms in universe are hydrogen Highly reactive Never exists as single atom in nature Hydrogen gas is diatomic (H 2 ) Nonmetal, but sits in group 1 why? TRENDS IN THE PERIODIC TABLE (4-3) 5 Trends in the Periodic Table 1. Ionization Energy 2. Atomic Radius 3. Electronegativity 4. Ionic Radius 5. Melting & Boiling points Ionization energy the energy required to Increases as move and/or to the Most difficult to remove an electron from fluorine 3

4 Two concepts: Distance of electrons from nucleus important Lots of electrons means energy levels Thus farther from nucleus, thus to remove Number of electrons in energy level important When only 1 or 2 in a level, the distance is, and there aren t that many protons holding in But when have 6 or 7 in a level, they are all at the distance, and additional protons hold them closer Atomic radius the radius of an atom Increases as you move and to the Makes sense that they get bigger as you move down, but why smaller as you move to the right? Electronegativity how strongly an atom attracts electrons Increases as you move and to the Fluorine is the most electronegative element Can you explain this phenomena? Ionic Radius Increases as move and to the Melting & Boiling Points Highest when d and p blocks are Lowest when d and p blocks Why? Unpaired electrons allow stronger bonds between atoms. Stronger bonds = higher melting points This is why mercury is a liquid! 4

5 WHERE DID THE ELEMENTS COME FROM? (4-4) Natural elements Most sources say 92 Book says elements are natural But Technetium, Promethium, and Neptunium are not found on Earth Where do natural elements come from? Most made inside during nuclear fusion Universe s origin Leading theory: All of the matter in universe was condensed into one tiny speck It exploded the no matter existed, only energy As cooled, formed electrons, protons, & neutrons These joined & formed hydrogen, maybe some helium Clouds of this condensed into stars Nuclear fusion Inside stars there is enormous temperature and pressure Forces atoms of hydrogen to into atoms of helium At the same time, releasing huge quantities of When the stars run low on hydrogen, they combine helium &/or other elements to create increasingly heavy elements up to iron Anything larger than iron requires a So the 93 natural elements come from the stars What about the 20+ other elements? Called the synthetic elements Synthetic elements are made in particle accelerators (AKA atom smashers ) Particle accelerator device that uses to propel particles to nearly the speed of light, then crash them into each other Been doing this since 1930 Creates only a few nuclei of the new element Most are and decompose in seconds or fractions of a second Ex. Uuq lasted 30 seconds 5

6 Newest particle accelerator is the at Cern (border of France & Switzerland) 27 km circular tunnel Researching subatomic particles 6