Periodic Table
ELEMENTS • All atoms of a specific element are alike • All atoms of different elements are different • 90 naturally occurring • Arranged on Periodic Table to show trends
Mendeleev (1869) • Organized table by... • Atomic mass • Thought pattern must exist between all elements • Elements in columns show similar properties… • Both physical and chemical! • Predicted properties of “missing” elements
Mendeleev’s Table
Moseley (c. 1914) • rearranged table by ... • Atomic number • determined atomic number of elements by determining number of protons in element
Moseley’s Table
Seaborg (1944) • rearranged Periodic Table with... • Lanthanide and Actinide Series pulled out/separated from main Periodic Table • discovered countless isotopes & 10 new elements
Before Seaborg
3-DAlexander’s Arrangement of Elements
Information from Periodic Table • Atomic number • Atomic mass • Chemical symbol • Chemical name
Periodic Law • The physical and chemical properties of the elements are periodic functions of their atomic number
Columns of Table = “groups” or “families” • Newer designation: 1-18 • 8 main families labeled with Roman Numeral and letter ‘A’ • Elements within the same family have similar but not identical properties • Electron configuration varies periodically
Rows of Table = “periods” • Properties are not alike within a period • 7 periods • Number of energy levels in atom • 2 additional rows at bottom of table are Lanthanide and Actinide series and belong to periods 6 and 7 • Seaborg's Extended Periodic Table
Group 1 or IA Group 2 or IIA Group13 or IIIA Group 14 or IVA Group 15 or VA Group 16 or VIA Group 17 or VIIA Group 18 or VIIIA Groups 3-12 Lanthanide & Actinide series Alkali metals Alkaline Earth metals Boron family Carbon family Nitrogen family Oxygen family Halogens Noble gases Transition metals Rare Earth metals Names of Families
Metals • Found to LEFT of zigzag line on table • Good conductors of heat & electricity • Malleable • Ductile • High melting points • Luster • Tend to lose electrons
Nonmetals • Found to RIGHT of zigzag line on table • Poor conductors of heat & electricity • Brittle when solid • Dull • Low melting points • Tend to gain electrons
Metalloids • Found along both sides of zigzag line • Properties of both metals & nonmetals • Okay conductors of heat & electricity • Shiny or dull
Trends • Valence number • Charge of ion • Tendency to gain or lose electrons • Reactivity • Atomic size (radius) • Metallic vs. nonmetallic properties • Ionization energy • Electron affinity • Electronegativity
Atomic Radius PERIOD 3 PERIOD 2
Ionization Energy PERIOD 2 PERIOD 3
Electronegativity PERIOD 2 PERIOD 3
Across a Period • radius decreases • ionization energy increases • electronegativity increases • b/c • number of valence electrons increases… • so EMF increases… • so valence electrons held more tightly…
Atomic Radius Family IA Family IIA
Ionization Energy Family IIA Family IA
Electronegativity Family IIA Family IA
Down a Family • radius increases • ionization energy decreases • electronegativity decreases • b/c • number of energy levels increases… • so valence electrons held less tightly…
Electron Organization • Found in electron clouds - also described as energy levels • Limited space in each cloud • Electrons want to be close to the nucleus because of EMF • Start with by filling the lowest energy level and working their way out. • Want to be in pairs.
Energy Levels
Valence Electrons for the 8 major families • Valence Electron = An electron located on the outer most shell • Roman Numeral tells number of valence electrons for all chemicals in the family. • Each element wants to achieve 8 valence electrons to be stable • Drawn as dot diagrams.
Electron Dot Diagram X Always start HERE X = Chemical Symbol = A valence electron
Octet Rule • The tendency of atoms to gain or lose electrons so they acquire eight electrons in their outer energy level
Who am I? • Use the clues and a periodic table to predict the element. • The number of clues is shown in the lower right corner.
1. Who am I? • Very good ability to conduct electricity • When combined with other elements, usually give up 1 valence electron • Only one letter in symbol • Potassium! (K) 3 clues
2. Who am I? • More valence electrons than oxygen • More protons than calcium • Fewer protons than krypton • Bromine ! (Br) 3 clues
3. Who am I? • Poor conductor • Usually found as a gas • Do not bond well with others (like to be alone) • Sometimes found in signs outside restaurants • Neon ! (Ne) 4 clues
4. Who am I? • Second largest atomic radius of period • One of most reactive in the family • One more proton than Rubidium • Strontium ! (Sr) 3 clues
5. Who am I? • Usually found as a gas • Very reactive • Lightest element in family • Often form -1 ion • Fluorine! (F) 4 clues
6. Who am I? • Radioactive • Highest atomic radius in family • Usually form -2 ion • Polonium ! (Po) 3 clues
7. Who am I? • Most commonly form +2 ion • Second highest number of protons in family • Second largest atomic radius in family • Barium! (Ba) 3 clues
8. Who am I? • All other members of family are metals • Most abundant element in universe • Hydrogen ! (H) 2 clues
9. Who am I? • Metals, nonmetals, and semi-metals all found in family • Same number of protons as the sum of the protons in the two elements directly above • 2nd greatest atomic radius in my family • Lead ! (Pb) 3 clues
10. Who am I? • Smallest atomic radius in my family • Family contains metals, nonmetals, and semi-metals • Can form positive or negative ion (call this the “skip” family) • Carbon ! (C) 3 clues
1. Who am I? • Very good ability to conduct electricity • When combined with other elements, usually give up 1 valence electron • 2nd largest atomic radius in group • Cesium! (Cs) 3 clues
2. Who am I? • More valence electrons than iodine • Fewer protons than rubidium • Can hurt Superman • Krypton (Kr) 3 clues
3. Who am I? • Poor conductor • Usually found as a gas • Do not bond well with others • Can make your voice sound funny • Helium ! (He) 4 clues
4. Who am I? • 2nd lowest atomic radius in the group • Has twice as many protons as the element above it • Can smell like rotten eggs • Sulfur ! (S) 3 clues
5. Who am I? • Has more valence electrons than lithium • Is a metal that sits on the ‘zig-zag’ line • Is not radioactive • Aluminum! (Al) 3 clues
6. Who am I? • Has 5 occupied energy levels • It is shiny and malleable • Has a symbol that isn’t derived from the it’s English name • Has a atomic number less than 75 • I am NOT very valuable. • Tin ! (Sn) 5 clues
7. Who am I? • Largest atomic radius on the periodic table • Francium (Fr) 1 clues
