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The History of your Periodic Table Ch. 5.1 The History of your Periodic Table Dmitri Mendeleev- (father of the periodic table) -Grouped elements in order of atomic mass -Elements with similar properties were placed in same column -HIS MOST IMPORTANT CONTRIBUTION 1. He left spaces open for undiscovered elements (big jumps in mass) 2. Predicted properties in those spaces with amazing accuracy The History of your Periodic Table Sir William Ramsay discovered three Noble Gases and added the group to Mendeleev’s table. Why were these elements hard to discover compared to the others? Lanthanides and the Actinides were the last elements added to the table. The History of your Periodic Table Henry Mosely-Grouped elements in order of atomic number -credited with modern periodic table Period Law-physical and chemical properties of elements are a periodic function of their atomic numbers Inner Transition Metal Placement Ch. 1.3 Periodic Table Periods -a horizontal row of elements. -Tells you the electron energy levels. Periodic Table Groups (families) -a vertical column of elements. -Tells us the # of valence electrons and the elements’ chemical properties for “A Main Group”(s,p) -d and f block makes up B Groups Ch. 1.3 Periodic Table 4 types of elements 1. metals 2. nonmetals 3. metalloids 4. Noble Gases Ch. 5.2 Families of the Periodic Table Periodic Table - Regions Transition Metals Inner Transition Metals Alkali Metals Group 1 Most reactive metals (one valence e-) Found as compounds (salts). Soft metals S-block Alkaline-earth Metals Group 2 Similar to Alkali but less reactive because they have 2 valence electrons Mostly found as compounds S-block Calcium Transition Metals Group 3-12 d-block Less reactive than group 1 and 2 Good conductors High Luster Transition Metals Hosts the only liquid metal mercury You can also find some of the most sample metals: gold, platinum, and palladium Inner Transition Metals Two rows at the bottom Rare earth reactive metals Actinoids are all radioactive 93 and above are manmade f-block Uranium P-Block Contain all four types of elements Other metals: Aluminum most abundant metal on Earth. More reactive than transition metals Metalloids (Semiconductors) 7 elements on the step Properties of both metals and non-metals. Silicon the most abundant element in Earth’s crust (computer chips) Arsenic is rat poison Silicon Arsenic Exposure Non Metals Are not able to conduct electricity or heat very well. Found in groups 13-17 with the exception of hydrogen. HYDROGEN It is not an alkali metal It is a nonmetal A very explosive gas. It is located in group one because it has one valence electron Carbon Found as an element (coal, diamond, graphite) Allotrophes Found in millions of different compounds Called Organic Compounds Oxygen and Nitrogen Oxygen is the most common atom found on Earth Nitrogen most common gas found in the atmosphere Halogens Group 17 Highly reactive Form salts with group 1 Used to kill bacteria (Cl, F, I) Bromine the only liquid nonmetal Noble Gases Group 18 Stable and inert gases Don’t form compounds. Full valence shell. Fun with He Xenon Bulbs Neon Krypton a stable violet colored gas? Ch. 5.3 Periodic Trends A pattern of characteristics that occur over and over again Ex days of the weeks There are many trends on the Periodic Table d-block does vary as much as s,p-blocks Metallic Trends Going left to right elements become less metallic Going Down elements become more metallic Atomic Radii Atomic Radii is measured by taking the distance from the nucleus to the outer energy level Can you tell me the trend? Atomic Radii As you go down a group you are adding an energy level, or another layer of electrons Atomic Radii As you go across the period, your atomic number increases When more protons exist in the nucleus, more positive charge produces stronger attractive forces on the electrons Ionization Energy (kJ/mol) The energy required to remove the most loosely held electron in the outer energy level of an atom. The less energy required, the more reactive the metal Ionization Energy Atomic Radii Needs more energy to be lost + + eeNeeds less energy to be lost Shielding Effect Ionization Energy–Why increase across period? The more valence electrons the atom has, the more energy it will need to lose its outer electron. Remember only metals want to lose electrons st 1 , nd 2 , rd 3 IE Reactivity for Metals Going down a group reactivity increases because the atom is more willing to give away its electron and react. (Ionization energy decreased) Brainiac Video Electronegativity/Electron Affinity Measure of an atoms attraction for an electron. Nonmetals have high attraction for electrons The higher the attraction the more reactive the nonmetal Electronegativity Electronegativity/Electron Affinity One exception- noble gases Why? They don’t want electrons, they are happy and full already Reactivity for nonmetals Going UP a group for nonmetals increases their reactivity The reason more electron affinity Flourine is the most reactive nonmetal. Ionic Radii Ions aren't the same size as the atoms they come from. Cations are smaller than the parent atom Anions are bigger than the parent atom Ionic Radii – Why Cations Smaller? By losing electrons, they also lose a whole energy level, therefore, becoming smaller in size Ionic Radii – Why anions bigger? When they gain electrons, the outermost becomes full. So less force is felt by the nucleus, the electrons spreads out. (becoming stable) Periodic Table Review