12/5/2016. Which of the following are main-group elements? Magnesium Vanadium Antimony Lead Neptunium Cesium Rutherfordium Boron Indium

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1 Learning Target: Classify elements according to their location on the Periodic Table This is a brief review of that information. Identify the following as being an alkalai metal, alkaline earth metal, transition metal, semi-conductor (aka metalloid), halogen, or noble gas: Germanium Tungsten Potassium Radon Strontium Uranium Silicon Beryllium Palladium Iodine Which of the following are main-group elements? Magnesium Vanadium Antimony Lead Neptunium Cesium Rutherfordium Boron Indium 1

2 Section 1: Who s Who??? Learning Target: Explain the development of Periodic Law 1817 Dobereiner Grouped elements in TRIADS Three elements with similar properties 1865 Newlands Arranged by increasing atomic MASS. Law of Octaves = Similar properties over EIGHT elements 1870 Mendeleev Created an 8 Column table based on ATOMIC MASS Elements with similar properties were in the same column Problems w/ Mendeleev s table: 1. Some elements did not fit the order he described. Ex: Tellurium (Te) and Iodine (I): he put them out of order in terms of atomic mass, but did this so they were in the same column as elements with similar properties (he broke his own rules) 2. There were gaps in the table BUT he was able to predict the properties and masses of the unknown elements very accurately. 2

3 1913 Moseley Studied X-ray spectra of elements and noticed they correlated with atomic number Arranged elements with increasing ATOMIC NUMBER PERIODIC LAW: Properties of the elements are a (periodic) function of their atomic number 1944 Glenn Seaborg Last rearrangement of the periodic table created the actinide series Dobereiner Triads Newlands Law of Octaves Mendeleev First 8 column table Mosley Periodic Law Seaborg Actinide Series Section 2 Atomic properties are determined by ELECTRON CONFIGURATION. Ex. 1s 2 2s 2 2p 6 3s 2 3p 3 Therefore the table is designed on the basis of electron configuration 3

4 Valence Electrons: Electrons that are found in an atom s outer most shell Determines chemical properties of an atom These are the electrons that can be gained, lost or shared when forming compounds OCTET RULE 8 electrons in the outer energy level renders an atom UNREACTIVE Unreactive = Very Stable So which elements are considered unreactive? A: The Noble Gases Atoms react with other atoms so all atoms end up with FULL OUTER ENERGY LEVELS (i.e. compounds) 1. They may add electrons 2. They may lose electrons 3. They may share electrons 4

5 Section 3 Learning Target: Identify properties of metals, nonmetals and metalloids Don t forget your color-coded periodic table It identifies the Groups Periods Main Group Elements It also classifies elements as Metals: Alkali metals Alkaline Earth metals Transition metals Lanthanide Series Actinide Series Other Metals Nonmetals: Noble gases Halogens Other nonmetals Metalloids: semiconductors Metals On the LEFT of the stairs Nonmetals On the RIGHT of the stairs Metalloids Attached to stairs METALS NONMETALS 1. Typically Solids 1. Gasses or BRITTLE solids 2. Shiny 2. Dull RULE of THUMB Metals: 3 or fewer outer energy level electrons 3. Conduct Heat and Electricity 4. Tendency when forming compounds to lose outer electrons 3. Insulators 4. Tendency when forming compounds to GAIN or SHARE electrons Nonmetals: 5 or more outer energy level electrons Metalloids: Properties of both Metals and Nonmetals aka Semiconductors 5

6 Increases 12/5/2016 What is a trend? Section 4 Learning Target: Describe element trends on the Periodic Table A predictable change in a particular direction (FOCUS ON MAIN GROUP ELEMENTS) Atomic Radii ½ the distance between the nuclei of identical atoms that are bonded together Atomic Radii increase from top to bottom and from right to left on the periodic table Radius = d/2 Increases Periodic Table Increases as you move down due to electron shielding electrons in the inner energy levels are between the nucleus and the outer electrons and therefore are shielded from being pulled away **More energy levels as you go down PT 6

7 Increases 12/5/2016 Decreases as you go right due to increasing charge of the nucleus (**means increases as you go left due to decreasing charge of nucleus) although more electrons are also present they are at the same distance from the nucleus b/c they are in the same energy level Stronger force of attraction, pulling electrons closer making radius smaller Gallium Yttrium Helium Hafnium Thallium Strontium Neon Vanadium Ions Atom or group of atoms that has a positive or negative charge Positive charge occurs when atom loses electrons Ex: Na + : Sodium that has lost an electron, and now has 10 e - Negative charge occurs when atom gains electrons Ex: Cl - : Chlorine that has gained an electron, and now has 18 e - This process that results in an ion requires energy this process is referred to as ionization Ionization Energy Energy required to remove one electron from a neutral atom of an element This happens when compounds form Ionization energy tends to increase from bottom to top and left to right Increases Periodic Table 7

8 As you move across, the nucleus gets larger and holds the electrons more tightly THEREFORE harder to remove Requires MORE energy (higher ionization energy) As you move down, the outer most electrons are farther away from the nucleus THEREFORE easier to remove Requires LESS energy (lower ionization energy) Iron Cesium Sulfur Iodine Cobalt Rhenium Tin Bismuth 8