Unit 3: The Periodic Table What is so periodic about it?

History of the PT Dmitri Mendeleev and Lothar Meyer: arranged the elements in order of atomic mass and found that certain properties repeated themselves at regular intervals. Some spaces in their periodic table were empty because some elements had not been discovered yet. Mendeleev was able to predict the properties of the elements that had not been discovered based on the repeating nature of the properties on the periodic table. 1 Henry Moseley: arranged the elements in order of increasing atomic #, and found that the elements fit a more regular pattern This is the way the periodic table is arranged today. Modern Periodic Law: When the elements are placed in order of increasing atomic #, elements with similar properties occur at periodic (regular and repeating) intervals. 2 3

Groups and Periods Groups: Periods: vertical columns of elements All elements in a group have the same # of valence e-. The last digit in the group # tells how many valence e- an element has (except groups 3-12) All elements in a group have similar chemical properties (because chemical properties depend on the number of valence e-) Periods: Horizontal rows of elements All elements in a period have the same # of PEL’s

Names of Groups Main Group Elements Group 1: Group 2: Alkali Metals Elements in groups 1, 2, and 13-18 are known as the main-group elements. The electron configurations of the elements in each main group are regular and consistent: the elements in each group have the same number of valence electrons. Four groups within the main group elements have special names. These groups are: Group 1: Because the Alkali metals only have a single valence electron, they are very reactive. By losing the 1 valence e-, they achieve a stable e- configuration. These metals are so reactive that the they are always found in compounds. They are named Alkali metals because they react with water to make alkaline solutions. **Hydrogen is not part of Group 1, it is only placed there because it has 1 valence e- Group 2: Also very reactive metals, but slightly less reactive than Group 1. Therefore the Alkaline Earth metals are usually found as compounds also. Alkaline Earth metals must lose 2 valence e- to become stable. It takes more energy to lose 2 e- than to lose 1 e- like the Alkali metals. Alkali Metals Alkaline Earth Metals

Halogens Group 17: Group 18: Noble Gases Most nonmetallic elements…they will often gain an e- to fill their valence shell. Halogens are very reactive and generally found in compounds or bonded to themselves. Group 18: Have 8 valence e- (a stable octet) Do not react because the outer shell is completely full. Transition Elements (Transition metals) Group 3-12: More dense metals than Groups 1+2 (heavy metals) Form different charges, depending on what they bond with. Transition elements can form colorful solutions when they are in compounds that are dissolved in water. Inner Transition Metals: Lanthanide series: an extension of period 6 #57-71 Actinide series: an extension of period 7 #89-103 Halogens Noble Gases Transition Metals Ex) CuSO4 (aq)

Groups of Groups: Metals Since most chemical properties are tied to the # of valence e- and element has, elements can be divided into 4 basic categories based on what they do with their valence e- when they bond. Metals: atoms that lose e- (are oxidized) and form positive ions (cations) when bonding with other elements. The most metallic elements are in the lower left hand corner of the PT. Have luster (shiny) Have malleability and ductility Thermal and electrical conductivity High melting points High density More than 2/3 of all elements are metals Alloy: mixture of metals by melting them together (not compounds)

Groups of Groups: Nonmetals atoms that gain e- (are reduced) and form negative ions (anions) when bonding with other elements. The most nonmetallic elements are in the upper right hand corner of the PT (not including group 18) Look dull Are brittle and hard (not malleable or ductile) Insulators Have low densities Have lower melting points There are only 11 nonmetals

Groups of Groups: Semimetals Semimetals (Metalloids): atoms that can gain e- (are reduced) or lose e- (are oxidized) and form positive or negative ions (cations or anions) when bonding with other elements. Have some properties of metals and some of nonmetals. Used in semiconductors (computer chips) There are 7 semimetals Remember the staircase

Groups of Groups: Noble Gases atoms that can neither gain e- nor lose e- and do not bond with other elements. Noble Gases have what is called a stable octet of e- ALL other elements want to be like Noble Gases and will react with other elements to become stable. Other elements bond in order to attain a “noble gas electron configuration”

Phases of Matter on the PT All of the information on the PT is given at STP and ground state. Liquids: Br + Hg Gases: H, N, O, F, Cl, Noble Gases Solids: everything else mp is below STP bp is above STP mp is below STP bp is below STP mp is above STP bp is above STP

Other categories on the PT Diatomics: elements that are always in a pair in nature. HOFBrINCl, or 7-H club

Other categories on the PT Diatomics: elements that are always in a pair in nature. HOFBrINCl, or 7-H club Radioactive: any element where ALL of the isotopes of that element are radioactive (the nucleus is unstable and breaks down spontaneously) Atomic # > 84 and 43, 61 Synthetic: man-made elements All are radioactive as well (they disintegrate in milliseconds) Atomic # > 93 and 43, 61 * * * * * * * * * * * * * * * * * * * * * * * *

Allotropes Allotropes: 2 or more different structural forms of the same element in the same phase. The chemical and physical properties of allotropes are different, because the atoms are bonded differently. Ex) O2(g) O3(g) Ex) C(s) C(s) This is oxygen in the gas phase. The oxygen that we breathe. It is clear. This is oxygen in the gas phase. This oxygen is ozone. It is blue and toxic. coal 8 graphite 6 4 diamond 5 Buckminster fullerene (bucky balls) 7

Periodic Table Trends: Shielding There is always an attraction of protons (in nucleus) to the electrons (in PEL’s). Shielding Effect: Describes how the kernel e- “block” the valence e- from the attraction to the protons in the nucleus. Depends on the # of kernel e-. What is the trend going down a group? increase Why? Weaker attraction btwn nucleus and valence e- due to more kernel e- and more PEL’s, What is the trend going across the period? Stays the same Same # of kernel e- and PEL’s Shielding increases 4 shells 5 shells Shielding stays the same

Periodic Table Trends: Atomic Radius Atomic (Covalent) Radius: The radius (size) of the atom. Atomic radius is measured in picometers (pm) Atomic radii are found on Table S What is the trend going down a group? increase Why? more PEL’s What is the trend going across the period? decreases # protons and electrons increases and attract to each other 32 37 130 84 60 62 Radius increases 215 142 136 136 Radius decreases

Periodic Table Trends: Ionic Radius the radius (size) of an ion. Cation: positive ion  loses e- and becomes smaller than its atom Anion: negative ion  gains e- and becomes larger than its atom Ex) Which is larger: Ca or Ca+2 Ex) Which is larger: O or O-2 It is always the one with more e- that is larger when comparing the atom and the ion. 20 e- 18 e- 8 e- 10 e-

Periodic Table Trends: Ionization Energy The amount of energy that it takes to pull away the outermost e- Ionization energies are found on Table S What is the trend going down a group? decrease Why? more shielding, more metallic, easier to lose e- What is the trend going across the period? increases more nonmetallic, smaller atoms, more valence e-, harder to lose e- 1312 2372 520 801 1681 2081 Ionization energy decreases 558 1170 403 1008 Ionization energy increases

Periodic Table Trends: Electronegativity What is the trend going down a group? decrease Why? more shielding, more metallic, easier to lose e- What is the trend going across the period? increases more nonmetallic, smaller atoms, more valence e-, easier to gain e- Noble Gases don’t have electronegativities because they don’ lose or gain e- Metals are generally 2.0 or lower. Nonmetals are generally higher than 2.0 Periodic Table Trends: Electronegativity Electronegatvity: The attraction for e- Electronegativities are found on Table S 2.2 -- 1.0 2.0 4.0 -- Electronegativity decreases 1.9 -- 2.0 2.2 -- 0.8 1.8 2.1 2.1 2.7 2.6 Electronegativity increases

Metallic character: The lower the ionization energy, the easier it loses e- Nonmetallic character: The larger the electronegativity, the easier it gains e- (not including grp 18)

Superlatives The largest atom on the PT is: The smallest atom on the PT is: The most electronegative element is: The least electronegative element is: The element with the highest ionization energy is: The element with the lowest ionization energy is:

Groups of 3 Group Roles: Objectives: Group leader: make sure all members of the group understand before moving on. Time keeper: keep the group on schedule so that you have enough time to finish. Organizer: get any materials the group may need and return them at the end of the period. Objectives: You will be able to explain the trends of shielding, atomic radius, ionization energy and electronegativity. You will be able to explain how these trends are inter-related.

For each of the elements below, look on Table S and find their atomic radius, ionization energy, and electronegativity and fill them in on the appropriate periodic table in your notes. H He Li B F Ne Rb In I Xe

Works Cited http://www.google.com/imgres?q=dmitri+mendeleev&hl=en&safe=active&gbv=2&tbm=isch&tbnid=on2EDTvgTt9STM:&imgrefurl=http://karlzbarkley.edu.glogster.com/false/&docid=nA1VOI2U6rOvEM&w=263&h=270&ei=BsB8TpHfL4Hb0QG32bUL&zoom=1&iact=hc&vpx=224&vpy=41&dur=1265&hovh=216&hovw=210&tx=132&ty=180&page=1&tbnh=96&tbnw=96&start=0&ndsp=10&ved=1t:429,r:6,s:0&biw=792&bih=395 http://www.google.com/imgres?q=lothar+meyer&hl=en&safe=active&gbv=2&tbm=isch&tbnid=Df8bZUcysEHg6M:&imgrefurl=http://en.wikipedia.org/wiki/Julius_Lothar_Meyer&docid=aDVWYd1YZJaGmM&w=150&h=178&ei=X8J8TtmNCoLu0gGK5tHvDw&zoom=1&iact=hc&vpx=545&vpy=116&dur=1421&hovh=142&hovw=120&tx=58&ty=86&page=4&tbnh=142&tbnw=120&start=17&ndsp=3&ved=1t:429,r:2,s:17&biw=792&bih=395 http://www.google.com/imgres?q=henry+moseley&hl=en&safe=active&gbv=2&tbm=isch&tbnid=yWS3DomqKIneSM:&imgrefurl=http://www.enotes.com/topic/Henry_Moseley&docid=EvUYIeIeSrSjfM&w=200&h=298&ei=zMJ8TvGFGqjg0QHf2ZDxDw&zoom=1&iact=hc&vpx=257&vpy=20&dur=3804&hovh=238&hovw=160&tx=88&ty=185&page=1&tbnh=95&tbnw=69&start=0&ndsp=14&ved=1t:429,r:2,s:0&biw=792&bih=395 http://www.google.com/imgres?q=molecular+structure+of+coal&hl=en&safe=active&gbv=2&tbm=isch&tbnid=W_kHdSohoznUlM:&imgrefurl=http://www.aist.go.jp/NIRE/publica/sgkkyo_e/sgkk7-4.htm&docid=rTcWkjScssg88M&w=210&h=137&ei=g8N8TuqjO6Le0QHX_6UW&zoom=1&biw=792&bih=395&iact=rc&dur=344&page=1&tbnh=84&tbnw=129&start=0&ndsp=8&ved=1t:429,r:7,s:0&tx=58&ty=38