Describe how Mendeleev arranged the elements in the periodic table Explain how the predictions Mendeleev made and the discovery on new elements demonstrated the usefulness of his periodic table 1. Antoine Lavoiser - organized known elements (very few) into metals, non metals, gases, and earth metals 2. Dmitri Mendeleev - organization based on a popular card game solitaire - each card had the elements name, mass, and properties - lined up the cards in order of increasing mass, found a pattern - elements with similar properties were in the same column Predictions - could not make a complete table, only had 63 elements leaving many spaces between elements - 3. used properties of other elements to predict undiscovered elements properties Evidence - named some of the missing elements, and predicted some of their properties. Ex. Eka- aluminum, eka-iodine) - 4. as elements were found scientists were able to verify properties and even explain chemical behaviors of elements in groups - 5.Medeleevs periodic table was completed before the discovery of protons. - by looking at certain trends, among the elements a new organization was created 6. Periodic Law - pattern of repeating properties displayed by elements in the periodic table 7. SO.the periodic table is now arranged by atomic number instead of atomic mass Describe the arrangement of elements in the modern periodic table Understand the trends that established the modern periodic table Locate periods and groups in the period table Definition - An electron that is in the highest occupied energy level of an atom - Determines the chemical properties of elements Valence Electrons Label your periodic table now Definition - Atoms tend to gain or lose electrons based on how many valence electrons they have. Ions are atoms or groups of atoms that have a positive or negative charge Chemical Bonding Chemical Bonding Atoms of elements are not chemically stable until they have 8 valence electrons. Atoms gain, lose or share electrons with other atoms to become chemically stable (have 8 valence electrons ). -Cations (+): Ions that have lost electrons, has more positive protons than negative electrons (Metals) - Sodium loses an electron and becomes a cation when it combines with other elements (Na + ) - Anion (-): Ions that have gained electrons, has more negative electrons than positive protons (non metals) - Chlorine gains an electron and becomes an anion and now ends in ide: Chloride Cl - This will determine the formula of IONIC Compounds A chemical compound in which ions are held together in a lattice structure by ionic bonds. They are composed of a metal (cation) and a nonmetal (anion) Three Regions - metals, and nonmetals, and metalloids Metals - include group and some elements from most known elements - good conductors of electricity/heat - solid at room temperature, except mercury ex. Na, Ag, Pb Definition - elements with properties that fall between those of metals and non metals - chemical properties will vary, usually most like the region they are closer to ex. As: closer to non metal most of its property will resemble that Definition - elements that are poor conductors of electricity/heat - low boiling points, SOmost are gases at room temperature - varying chemical properties ex. He, F, P An ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Consists of a cation (metal) and an anion (nonmetal) Examples: NaCl Sodium Chloride MgO Magnesium Oxide LiBr Lithium Bromide K 3 N Potassium Nitride Write a formula for potassium sulfide. 1. Identify the cation and anion. potassium = K + sulfide = S 2 2. Balance the charges. K + S 2 K + 2(1+) + 2(1-) = K + and 1 S 2 = K 2 S 1.Write the charge of the cation as a superscript. 2.Write the charge of the antion as a superscript. 3.Criss cross the superscripts and make them subscripts 4.Reduce when possible. Sodium Chloride Magnesium Oxide Lithium Bromide Potassium Nitride Calcium Oxide Aluminum Sulfide Iron (II) Oxide Transition Metals have variable charges that will be indicated by a Roman Numeral. Ex : CrO 3 Chromium (III) Oxide Polyatomic Ions have their own names Ex: CaSO 4 Calcium Sulfate Acids have different naming rules. Acids always start with Hydrogen Ex: H 2 SO 4 Sulfuric Acid Memorize the left side by next class Atomic Radii: - half the distance between the nuclei of the same atoms bonded together -Atomic Radius increases down a group and decreases across a period from left to right Ionization energy: - amount of energy required to pull an electron away from an atom to form a positively charged ion - generally increases with increasing atomic number - at some points, when atomic number increases there is a dramatic decrease ex. Li, Na, K, Rb, Cs, Fr Electronegativity is the tendency of an atom to attract a bonding pair of electrons. Electronegativity also generally increases with increasing atomic number across a period from left to right and increases moving up a group. Fluorine is the most electronegative element while Cesium and Francium are the least. Electron affinity is the energy released when an atom gains an electron. Decreases from top to bottom in a group and increases from left to right across a period. Shielding or nuclear shielding is a term used to describe the core electrons ability to shield the valence electrons from the charge of the nucleus. The larger the atomic radius the higher the shielding effect is within an atom. 7 periods (Across) - Atomic Radius decreases - Ionization energy increase - Electron Affinity increases 18 Groups (Down) - Atomic Radius increases - Ionization energy decreases - Electron affinity decreases - Elements have similar chemical and physical properties - # of valence electrons are the same Families/Groups Alkali metals Alkali Earth metals Boron Family Carbon Family/ Chalcogens Nitrogen Family Oxygen Family Transition Metals Halogens Noble Gases Unlike any other element Very reactive Gas at room temperature Belongs to its own group of one. Most common element in the universe Definition - highly reactive metallic elements in group 1 - react violently with water to form hydrogen and alkaline solutions - Must be stored in oil, burn when exposed to air - al-quili means wood ashes - one outer electron, by losing this electron they become a cation, and become stable - Low density and low MP - soft metals; can be cut with a knife - shiny, but dull quickly due to oxygen and water in air - good conductors - gaseous states at high temperatures become plasmas ex. Na, Cs, Rb Ex: See Video Demo Definition - comes from idea of Earth, materials unable to light on fire - Occur as carbonates, phosphates, sulfates - Mostly form ionic compounds - reactive metallic elements with two electrons in the outermost energy level - harder, denser, stronger and have higher melting points, lower reactivity than alkali ex. Be, Ca, Mg Groups 3-18 Contain 1 or 2 valence electrons Brittle metals High MP and BP Excellent conductors of electricity and heat Most are silver except for copper and gold Include radioactive elements Includes Mercury(Hg), only liquid metal at RT Tend to have 2 or more oxidation states so their ionic charge may vary Lanthanides - shiny, metallic transition metals ( 58 71) in which electrons are added to 4f orbitals - located at the bottom of the periodic table for convenience Actinides -shiny metallic transition metals ( 90 103) in which electrons are added to 5f orbitals -located at the bottom of the periodic table for convenience -radioactive Do not occur elementally in nature except aluminum, which is the most abundant metallic element All are metals except Boron which is a metalloid Low Melting points From the Greek word for Ore-Forming since they are all found in copper ore. Includes a nonmetal, C, 2 metalloids, Si & Ge, and 2 metals, Sn & Pb. Tend to form covalent bonds except for tin and lead which form ionic bonds Consists of 2 nonmetals, N & P, 2 metalloids, As & Sb, and one metal, Bi. Nitrogen and Phosphorous are abundant in the atmosphere Properties vary widely Occur elementally in nature in a diatomic or polyatomic state Tend to form covalent bonds Consists of 3 nonmetals(O,S, Se), one metalloid, Te, and one metal, Po Properties Vary Term comes from Greek means salt former Combines with many metals to form salts Nonmetallic elements that have 7 valence electrons Most reactive group of nonmetals varying physical properties, similar chemical properties Characterized by low reactivity and by an octet of electrons (happy) Term comes from noble people, did not associate with anyone other then their kind Helium only has 2 electron and is considered full All are colorless, odorless gases