Química de Materiales o mejor….Fisico Quimica de materiales Prof Aldo Romero Cinvestav Unidad Queretaro

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.

Periodic Table  This table is a remarkable way to show the manifold relationships between differing kinds of elements  The modern table was devised in 1869 by Dimitri Mendeleyev  He arranged the elements by weight and by their chemical properties

Periodic Table  "...if all the elements be arranged in order of their atomic weights a periodic repetition of properties is obtained." - Mendeleyev

Groups…Here’s Where the Periodic Table Gets Useful!!  Elements in the same group have similar chemical and physical properties!!  (Mendeleev did that on purpose.) Why?? They have the same number of valence electrons. They will form the same kinds of ions.

Dimitri Mendeleev: Father of the Table HOW HIS WORKED…  Put elements in rows by increasing atomic weight.  Put elements in columns by the way they reacted. SOME PROBLEMS…  He left blank spaces for what he said were undiscovered elements. (Turned out he was right!)  He broke the pattern of increasing atomic weight to keep similar reacting elements together.

Dmitri MendeleevDmitri Mendeleev (1869) Dmitri Mendeleev In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date. The periodic table is base on the similarity of properties and reactivities exhibited by certain elements. Later, Henri Moseley ( England, ) established that each elements has a unique atomic number, which is how the current periodic table is organized.

The Current Periodic Table  Mendeleev wasn’t too far off.  Now the elements are put in rows by increasing ATOMIC NUMBER!!  The horizontal rows are called periods and are labeled from 1 to 7.  The vertical columns are called groups are labeled from 1 to 18.

The Periodic Table A map of the building block of matter.

Families on the Periodic Table  Columns are also grouped into families.  Families may be one column, or several columns put together.  Families have names rather than numbers. (Just like your family has a common last name.)  We will learn later why the elements can be arranged in this fashion based on the arrangements of the electrons outside the nucleus

Periods and Groups  Sizes of the atoms decrease as we move from left to right across a period  This is due to the increasing number of protons in the nucleus, so the electrical attraction between the nucleus and the orbiting electrons gets stronger and pulls the electrons closer to the nucleus

Periods and Groups  We can display the table to demonstrate other properties as well  As you move from left to right across a period, the ability of the atom to attract another electron increases  This property is called electronegativity

Periods and Groups  All the elements in a column have remarkably similar chemical properties  Some of the columns have been given special names to distinguish them  The first group is called the alkali metals  The second group is the alkaline-earth metals

Periods and Groups  Groups 3-12 are called the transition metals  Groups are not named  Group 16 are the chalcogens  Group 17 are the halogens  Group 18 are the noble gases and are basically inert

Periodic Table Expanded View  The way the periodic table usually seen is a compress view, placing the Lanthanides and actinides at the bottom of the stable.  The Periodic Table can be arrange by subshells. The s-block is Group IA and & IIA, the p-block is Group IIIA - VIIIA. The d-block is the transition metals, and the f-block are the Lanthanides and Actinide metals

Periodic Table: Metallic arrangement  Layout of the Periodic Table: Metals vs. nonmetals Metals Nonmetals

Periodic Table: The three broad Classes Main, Transition, Rare Earth  Main (Representative), Transition metals, lanthanides and actinides (rare earth)

Reading the Periodic Table: Classification  Nonmetals, Metals, Metalloids, Noble gases

Across the Periodic Table  Periods: Are arranged horizontally across the periodic table (rows 1-7)  These elements have the same number of valence shells. 2nd Period 6th Period

Down the Periodic Table  Family: Are arranged vertically down the periodic table (columns or group, or 1-8 A,B)  These elements have the same number electrons in the outer most shells, the valence shell. Alkali Family: 1 e- in the valence shell Alkali Family: 1 e- in the valence shell Halogen Family: 7 e- in the valence shell Halogen Family: 7 e- in the valence shell

Infamous Families of the Periodic Table  Notable families of the Periodic Table and some important members: Alkali Alkaline (earth) Transition Metals Noble Gas HalogenChalcogens

Important members - the Elements Individual members of selected Elements & their characteristics H He Li Na KCa Mg Fe I Cl F P SSi ONC Al Zn Cu Ag Br

Periodic Table e - configuration from the periodic periodic table B 2p 1 H 1s 1 Li 2s 1 Na 3s 1 K 4s 1 Rb 5s 1 Cs 6s 1 Fr 7s 1 Be 2s 2 Mg 3s 2 Ca 4s 2 Sr 5s 2 Ba 6s 2 Ra 7s 2 Sc 3d 1 Ti 3d 2 V 3d 3 Cr 4s 1 3d 5 Mn 3d 5 Fe 3d 6 Co 3d 7 Ni 3d 8 Zn 3d 10 Cu 4s 1 3d 10 B 2p 1 C 2p 2 N 2p 3 O 2p 4 F 2p 5 Ne 2p 6 He 1s 2 Al 3p 1 Ga 4p 1 In 5p 1 Tl 6p 1 Si 3p 2 Ge 4p 2 Sn 5p 2 Pb 6p 2 P 3p 3 As 4p 3 Sb 5p 3 Bi 6p 3 S 3p 4 Se 4p 4 Te 5p 4 Po 6p 4 Cl 3p 5 Be 4p 5 I 5p 5 At 6p 5 Ar 3p 6 Kr 4p 6 Xe 5p 6 Rn 6p 6 Y 4d 1 La 5d 1 Ac 6d 1 Cd 4d 10 Hg 5d 10 Ag 5s 1 4d 10 Au 6s 1 5d 10 Zr 4d 2 Hf 5d 2 Rf 6d 2 Nb 4d 3 Ta 5d 3 Db 6d 3 Mo 5s 1 4d 5 W 6s 1 5d 5 Sg 7s 1 6d 5 Tc 4d 5 Re 5d 5 Bh 6d 5 Ru 4d 6 Os 5d 6 Hs 6d 6 Rh 4d 7 Ir 5d 7 Mt 6d 7 Ni 4d 8 Ni 5d 8

Periodic Table: electronbehavior The periodic table can be classified by the behavior of electrons

2. Trend in Atomic Radius  Atomic Radius:  The size of at atomic specie as determine by the boundaries of the valence e-. Largest atomic species are those found in the SW corner since these atoms have the largest n, but the smallest Z eff.

3. Trend in Ionization Potential Ionization potential: The energy required to remove the valence electron from an atomic specie. Largest toward NE corner of PT since these atoms hold on to their valence e- the tightest.

4. Trend in Electron Affinity Electron Affinity: The energy release when an electron is added to an atom. Most favorable toward NE corner of PT since these atoms have a great affinity for e-.

Summary of Trend  Periodic Table and Periodic Trends  1. Electron Configuration 2. Atomic Radius: Largest toward SW corner of PT 3. Ionization Energy: Largest toward NE of PT 4. Electron Affinity: Most favorable NE of PT

Summary  Periodic Table: Map of the Building block of matter  Type: Metal, metalloid and Nonmetal  Groupings: Representative or main, transition and Lanthanide/Actanides  Family: Elements in the same column have similar chemical property because of similar valence electrons  Alkali, Alkaline, chalcogens, halogens, noble gases  Period: Elements in the same row have valence electrons in the same shell.

Lots of Questions  Why are there only two elements in the first period?  Why are there eight elements in the second and third periods?  Why do we jump to eighteen in the fourth period?  Why are the chemical properties of a group so similar?

Hydrogen  Hydrogen belongs to a family of its own.  Hydrogen is a diatomic, reactive gas.  Hydrogen was involved in the explosion of the Hindenberg.  Hydrogen is 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

Alkaline Earth Metals  Second column on the periodic table. (Group 2)  Reactive metals that are always combined with nonmetals in nature.  Several of these elements are important mineral nutrients (such as Mg and Ca

Transition Metals  Elements in groups 3-12  Less reactive harder metals  Includes metals used in jewelry and construction.  Metals used “as metal.”

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 the 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 or Chalcogens  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  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, monatomic gases  Used in lighted “neon” signs  Used in blimps to fix the Hindenberg problem.  Have a full valence shell.