The Periodic Table Good afternoon! Please get your notebook and be in your seat when the bell rings.
Pre-Periodic Table Chemistry … …was a mess!!! No organization of elements. Imagine going to a grocery store with no organization!! Difficult to find information. Chemistry didn’t make sense.
Dmitri Mendeleev: Created The Periodic Table HOW HIS WORKED… Elements arranged in rows (periods) by increasing atomic mass. Elements arranged in columns (families) by the way they reacted. SOME PROBLEMS… Left blank spaces for what he said were undiscovered elements. (Turned out he was right!) Pattern of increasing atomic mass was broken to keep similar reacting elements together. http://upload.wikimedia.org/wikipedia/commons/b/b3/Medele eff_by_repin.jpg
The Current Periodic Table In 1913, Henry G.J. Moseley, an English scientist, arranged the elements based on increasing atomic number. http://www.chemistryexplained.com/Ma-Na/Moseley-Henry.html
Groups Vertical columns are called groups or families Groups are numbered 1 to 18.
Groups…Here’s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!! Example: Elements in Group 1 are highly reactive and can be explosive in water. http://www.teachertube.com/view Video.php?video_id=41344 http://www.teachertube.com/view Video.php?video_id=41344 They have the same number of valence electrons. http://www.tutorvista.com/content/science/sci ence-i/structure-atom/valence-shell- electron.php Why?
Valence Electrons Electrons farthest away from the nucleus are most loosely held. Ranges from 1 to 8 valence electrons Many properties of the atom, and therefore of an element, are determined by the number of valence electrons. http://www.tutorvista.com/content/science/sci ence-i/structure-atom/valence-shell- electron.php
Periods Horizontal rows numbered 1 to 7. Elements in the same period have the same number of electron shells or energy levels.
Properties of Elements on the Periodic Table An element’s physical and chemical properties can be predicted from its location in the periodic table Example: Sodium is more reactive than Aluminum Reactivity in metals decreases as you go from left to right. For nonmetals, the opposite is true. Nonmetals in Groups 14 through 17 become more reactive from left to right. Group 18, the Noble Gases, are an exception.
Metals: Left/Middle of Periodic Table Shiny, metallic Conduct heat and electricity Malleable and ductile (reshape) Give up valence electron in a reaction Copper Nickel Aluminum Gold Silver Mercury
Metalloids: Zigzag on Periodic Table where metals and nonmetals meet Mostly shiny, metallic looking Only semi-conductive Often combined with non-metals
Non-Metals: Right side of Periodic Table Dull, not shiny, many are GAS Do not conduct heat or electricity Crumble or break if solid (non-malleable/ductile) Neon Helium Iodine ChlorineCarbon Sulfur Gain or share electrons in a chemical reaction
Hydrogen Belongs to a family of its own. Diatomic, reactive gas. Was involved in the explosion of the Hindenburg aircraft. Promising as an alternative fuel source for automobiles
Alkali Metals 1 st column on the periodic table (Group 1) not including hydrogen. Very reactive metals Always combined with something else in nature (like in salt). Soft enough to cut with a butter knife 1 valence electron
Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals Always combined with nonmetals in nature. Several are important mineral nutrients (Mg and Ca) 2 valence electrons
Transition Metals Elements in groups 3-12 Less reactive harder metals Includes metals used in jewelry and construction.
Boron Family Elements in group 13 Aluminum metal was once rare and expensive, not a “disposable metal.”
Carbon Family Elements in group 14 Contains elements important to life and computers. Carbon is the basis for an entire branch of chemistry. Silicon and Germanium are important semiconductors.
Nitrogen Family Elements in group 15 Nitrogen makes up over ¾ of Earth’s atmosphere. Nitrogen and phosphorus are both important in living things. Most of the world’s nitrogen is not available to living things. The red stuff on the tip of matches is phosphorus.
Oxygen Family Elements in group 16 Oxygen is necessary for respiration. Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)
Halogens Elements in group 17, also called Halides Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature Used as disinfectants and to strengthen teeth
The Noble Gases Elements in group 18 VERY unreactive (STABLE), monatomic gases Used in lighted “neon” signs Used in blimps to fix the Hindenburg problem. Have a full valence shell.
One of two rows that “sits off” to the bottom of the periodic table Reactive Fairly soft metals Lanthanide Series
Also towards bottom of periodic table All are radioactive, some are not found in nature Some with higher atomic numbers have only been made in labs Actinide Series
Electron Configuration http://www.chemprofessor.com/periodicqm.htm http://www.youtube.com/watch?v=jtYzEzykFdg http://www.youtube.com/watch?v=2AFPfg0Como Click on the video links for explanations of electron configuration.
Pre-AP Periodic Trends Atomic Radius – related to the atom’s volume. − Period – atomic radius decreases as you go from left to right − Group – atomic radius increases as you go down a group
Pre-AP Periodic Trends Electronegativity – the atoms “desire” to grab another atom’s electrons. − Period – electronegativity increases as you go from left to right − Group – electronegativity decreases as you go down a group
Pre-AP Periodic Trends Ionization Energy – amount of energy needed to remove the outermost electron. Closely related to electronegativity. − Period – Ionization energy increases as you go from left to right − Group – Ionization energy decreases as you go down a group
Pre-AP Periodic Trends Reactivity – how likely or how vigorously an atom is to react with another substance. Non-Metals − Period - reactivity increases as you go from left to right, except for Group 18 − Group – reactivity decreases as you go down the group Metals − Period – reactivity decreases as you go from left to right − Group – reactivity increases as you go down a group
Pre-AP Periodic Trends Melting Point Metals – the melting point for metals decreases as you go down a group Non-Metals – the melting point for non-metals increases as you go down a group