Periodic Trends The Organization of the Elements
Warm Up Activity• Provide the Electron Configurations for the following elements: – H – Li – Na – K – Rb – Cs – Fr• Do you notice any patterns/trends/similarities in their electron configurations?• Do you notice any patterns/trends/similarities in their location on the periodic table?
Periodicity• Periodicity: Refers to the inherent reoccurring nature of certain properties within the elements at specific predictable intervals.• There are repeating patterns within the elements.• Certain elements have many properties in common and can be grouped together into specific families.• Has Everything to do with the number and location of electrons.
The Periodic Table• The periodic table is a invaluable tool that arranges the elements in a very specific way.• It groups “like” elements together by their properties.• The periodic table has a number of trends within in it.• ESSENTIAL organizational tool for chemists
Early Attempts• Believe it or not chemists did not immediately stumble upon the current periodic table. – There were many many attempts at creating a working model, that met with varying degrees of success, before the modern periodic table we all recognize was developed.
Mendeleev• Our modern periodic table is based on the work of Dimitri Mendeleev who was the first scientist to publish an functioning organized table of the known elements.• Based his table on 2 factors: similarities in chemical and physical properties and atomic mass.• Mendeleev even went out on a limb and predicted the properties of 2 at the time undiscovered elements.• He was very accurate in his predictions, which led the world to accept his ideas about periodicity and a logical periodic table.
“Periodic Law”• Mendeleev’s Table was very good but not perfect.• Moseley proposed the idea of a Periodic Law which states: – When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties. – Focuses on atomic number instead of atomic mass
The Periodic Law• The periodic table organizes the elements into Groups/Families and Periods.• Groups or Families: Atoms with similar properties appear in vertical columns on the periodic table. – We now know they are similar because they all have the same number of valence (outer shell) electrons, which governs their chemical behavior.• Periods: Contain elements within the same energy level or shell. – The elements within a period all have the same n (Primary Quantum Number).
Periodic Table e- configuration from the periodic periodic table 1 18 IA VIIIA 2 13 14 15 16 171 H IIA IIIA IVA VA VIA VIIA He 1s1 1s22 Li Be B •B C N O F Ne •2p2 1 2p3 2p5 2s1 2s2 2p1 2p 2p4 2p6 Na Mg 3 4 5 6 7 8 9 10 11 123 IIIB IVB VB VIB VIIB VIIIB IB IIB Al Si P S Cl Ar 3s1 3s2 3p1 3p2 3p 3 3p4 3p5 3p64 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Be Kr 4s1 4s2 3d1 3d2 3d3 4s13d5 3d5 3d6 3d7 3d8 4s13d10 3d10 4p1 4p2 4p3 4p4 4p5 4p65 Rb Sr Y Zr Nb Mo Tc Ru Rh Ni Ag Cd In Sn Sb Te I Xe 5s1 5s2 4d1 4d2 4d3 5s14d5 4d5 4d6 4d7 4d8 5s14d10 4d 10 5p1 5p2 5p3 5p4 5p5 5p66 Cs Ba La Hf Ta W Re Os Ir Ni Au Hg Tl Pb Bi Po At Rn 6s1 6s2 5d1 5d2 5d3 6s15d5 5d5 5d6 7 5d 5d8 6s15d10 5d10 6p1 6p2 6p3 6p4 6p5 6p67 Fr Ra Ac Rf Db Sg Bh Hs Mt 7s1 7s2 6d1 6d2 6d3 7s16d5 6d5 6d6 6d7
Grouping the Elements by PropertiesCLASSES OF ELEMENTS
Major Categories• Metals: are conductors of heat and electricity, lustrous (shiny), malleable, ductile, and generally solid.• Nonmetals: may be solids, liquids, or gases, and are poor conductors of heat and electricity. When solids, they are brittle, non-lustrous materials.• Metalloids: are solids at standard conditions, and are semiconductors of electricity, making them handy for use in the electronics field. Metalloids have properties between that of metals and nonmetals, causing them to have the nickname of "semimetals."
Location on Periodic Table• The periodic table tells you where the metallic, nonmetallic, and semimetallic elements are.• Look for the line that looks like a staircase. – Elements left of this line are metals. – Elements to the far right of this line are nonmetals – Elements touching the line on either side are semimetals, or metalloids
Other Locations• Main block elements: These are the s- and p- sections of the periodic table (groups 1,2, 13-18)• Transition elements: These are the elements in• the d- and f-blocks of the periodic table. – The term “transition element”, while technically referring to the d- and f-blocks, usually refers only to• the d-block. – Technically, the d-block elements are the “outer• transition elements” – Technically, the f-block elements are the “inner transition elements”
Group 1: Alkali Metals All Alkali Metals have 1 Valence Electron. Highly Reactive! • Alkali metals are NEVER found pure in nature; they are too reactive. Potassium, K Flammable in air and water. reacts with water Reactivity of these elements and must be stored in increases down the group. kerosene Low melting (MP of Li = 181° C, Na = 98° C) and Boiling Points. They are light, low-density (Li = 0.535, Na = 0.968 g/ml), soft metals.
Group 2: Alkaline Earth Metals• All alkaline earth metals have 2 valence electrons• They are also reactive, but less so than the alkali metals.• They are light, soft metals, but stronger and denser than the alkali metals. (Density of Ca = 1.55, Mg = 1.74 g/ml).• Alkaline earth metals are not found pure in nature; they are too reactive.• Low MP and BP, but higher than alkali metals (MP of Ba= 302 °C, Mg = 649 °C)• The word “alkaline” means “basic” – common bases include salts of the metals • Ca(OH)2 • Mg(OH)2
Groups 3-12: Transition MetalsThey are less reactive than the alkali and alkaline earth metals, but vary greatly among themselves in reactivity- generally stable.Most are hard solids with high melting and boiling points. (Fe = 1535° C, Ti = 1660° C).Typically High density (Fe = 7.87, Ir = 22.4 g/ml)Share many of the general Copper, Cu, is a relatively soft Mercury, Hg, is the characteristics of all metals metal, and a very only metal that good electrical exists as a liquid at conductor. room temperature
Inner Transition Metals• Lanthanides (4f section)• – Also called the rare earth metals, because they’re rare. – Usually intermediate in reactivity between alkaline earth metals and transition metals. – High MP and BP – Used in light bulbs and TV screens as phosphors.• Actinides (5f section)• – Many have high densities – Most are radioactive and manmade – Melting points vary, but usually higher than alkaline earth metals. – Reactivity varies greatly – Used for nuclear power/weapons, radiation therapy, fire alarms.
Properties of Metalloids They have properties ofboth metals and nonmetals.Metalloids are more brittlethan metals, less brittle thanmost nonmetallic solids Metalloids aresemiconductors of electricity Some metalloids possessmetallic luster
Nonmetals Nonmetals are poorconductors of heat andelectricity Nonmetals tend to bebrittle Many nonmetals are gasesat room temperature Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
Group 17: Halogens Halogens all have 7 valence electrons. These elements are highly reactive. Halogens are never found pure in nature; they are too reactive. Highly volatile – F and Cl are gases, Br is a volatile liquid, and I is an easily sublimed solid. Strong oxidizers – they readily pull electrons from other atoms. All are also extremely dangerous, especially when inhaled. Halogens in their pure form are diatomic molecules (F2, Cl2, Br2, and I2) Chlorine is a yellow-green poisonous gas
Group 18: Noble Gases Have full electron shells Noble gases have 8 valence electrons (except helium, which has only 2) Noble gases are ONLY found pure in nature – they are chemically unreactive. Colorless, odorless, and unreactive; they were among the last of the natural elements to be discovered Used to provide the atmosphere in situations where you don’t want chemical reactions to occur (light bulbs, glove boxes, etc).
Hydrogen• Hydrogen – “The Weirdo”• – Has properties unlike any other element – Diatomic – H2 – Can form either a +1 or -1 charge – Relatively unreactive unless energy is added (under most conditions) – it can form explosive mixtures with oxygen (as it did in the Hindenburg explosion)