updated october 2006 created by c. ippolito september 2006 elements, atoms, and the periodic table...
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Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Elements, Atoms, and the Elements, Atoms, and the Periodic TablePeriodic Table
Unit Objectives:Unit Objectives:1.1. Identify the names, symbols and origin of chemical elements;Identify the names, symbols and origin of chemical elements;2.2. Appreciate relative abundance of various elements;Appreciate relative abundance of various elements;3.3. Identify the different kinds of elements represented in the Identify the different kinds of elements represented in the
periodic table;periodic table;4.4. Recognize the major properties used to distinguish the Recognize the major properties used to distinguish the
different types of elements;different types of elements;5.5. Appreciate the historical development of the atomic theory;Appreciate the historical development of the atomic theory;6.6. Explain and describe the atomic structure of elements and Explain and describe the atomic structure of elements and
how it relates to their individual propertieshow it relates to their individual properties
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Elements: Ancient and Modern Elements: Ancient and Modern TheoryTheory
• Robert Boyle – 1661 - “The Sceptical Chymist”
• Element– Substance that cannot be broken into simpler
substances
• Compound– Formed when two or more elements combine
• Antoine Lavoisier (1743-1794)– 1789 – “Elementary Treatise on
Chemistry”• Identified 33 “elements”
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Chemical SymbolsChemical Symbols
• alchemists used secret codes– signs for known elements
• shorthand used to represent elements– JJ Bersalius
• each element is represented a one or two letter symbol with the first letter always capitalized
• symbol derived from first letter of name, if already assigned take a second letter from name
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Chemical Names and SymbolsChemical Names and Symbols
• English named– aluminum (Al)– argon (Ar)– arsenic (As)– carbon (C)– calcium (Ca)
• Honorary named– Curium (Cm)– Californium (Cf)
• Latin named– gold [aurum] (Au) – iron [ferrum] (Fe)– lead [plumbum] (Pb) – mercury [hydragyrum] (Hg) – silver [argentum] (Ag)– sodium [natrium] (Na)– tin [stannum] (Sn)
• German named– tungsten [wolfram] (W)
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Abundant and Rare ElementsAbundant and Rare Elements
• 11 elements form 99% of earth crust
- oxygen- silicon- aluminum- iron- calcium- sodium
- potassium- magnesium- hydrogen- titanium- chlorine
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Periodic Table of ElementsPeriodic Table of Elements
• metals • metalloids • nonmetals
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Organization of Periodic TableOrganization of Periodic Table
• Rows– form periods
• Columns– form groups or families
• Classroom Table– REDRED
• gaseous elements
– BLUEBLUE• liquid elements
– BLACKBLACK• solid elements
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
MetalsMetals• Physical Properties – solid, except Hg
– Conductivity• good conductors of heat and electricity
– Luster• shiny surface
– Malleability• may be hammered or rolled
– Ductility• may be drawn into wires
– Hardness• varies
– hard – Cr, Fe, Mn– soft – Au, Pb, Na
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
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NonmetalsNonmetals• Physical Properties – solid, liquid, gas
– Conductivity• poor conductors of heat and electricity
– Luster• NONO, dull surface
– Malleability• NONO, brittle – crumble when hit
– Ductility• NONO
– Hardness• NONO
– carbon (diamond) exception
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September 2006September 2006
MetalloidsMetalloids
• some properties like metals others like nonmetals– semiconductors
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
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Early Atomic StructureEarly Atomic Structure• DemocritusDemocritus
– Atomic Theory of MatterAtomic Theory of Matter• all matter could be divided into tiny
indivisible particles called atomsatoms • different types of atoms existed for each
different type of material• not based on experimental evidence
• AristotleAristotle– Continuous Theory of MatterContinuous Theory of Matter
• all matter was continuous and always could be divided into smaller parts without end
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September 2006September 2006
Law of Conservation of MassLaw of Conservation of Mass• Antoine LavoisierAntoine Lavoisier
– Father of Modern ChemistryFather of Modern Chemistry• quantitatively measured mass
of reactants and compared it with mass of products
• found mass remained constant– Law of Conservation of MassLaw of Conservation of Mass
• matter can be changed but cannot be created nor destroyed
• combustion combines elements with oxygen
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September 2006September 2006
Law of Definite ProportionsLaw of Definite Proportions• Joseph ProustJoseph Proust
– regardless of where a substance came from or how large the sample
– specific substances always contained elements in the same ratio by mass
• Law of Definite ProportionsLaw of Definite Proportions
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September 2006September 2006
Dalton’s Atomic TheoryDalton’s Atomic Theory
• John Dalton– postulates to explain Lavoisier’s and
Proust’s findings1. Matter made of small particles (atoms)2. Atoms are indestructible. Cannot be
created or destroyed in chemical or physical changes.
3. Atoms of same element are identical, have the same mass.
4. Atoms of different elements are different, have different mass
5. Compounds form by combining atoms of different elements
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Parts of the AtomParts of the Atom
• in the late 1800’s experiments show that atoms are made of smaller particles– ElementaryElementary or Subatomic ParticlesSubatomic Particles
• proton proton – positive charge, mass = 1 amu, in nucleus– positive charge, mass = 1 amu, in nucleus• electron electron – negative charge, mass = 1/1837 amu, outside nucleus– negative charge, mass = 1/1837 amu, outside nucleus• neutron neutron – neutral charge, mass = 1 amu, in nucleus– neutral charge, mass = 1 amu, in nucleus
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Elements and IsotopesElements and Isotopes
• Isotope– atoms of the same element that have different mass
• same atomic number– same number of protons and electrons
– same behavior
• mass differs because the atoms have different numbers of neutrons
• Isotopes of Hydrogen– Protium 1
1H
– Deuterium 21H
– Tritium 31H
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
Atomic MassesAtomic Masses
• for an individual atom is a whole number– atomic mass = # of protons + # of neutrons
• for an element it is the average of the atomic masses of all existing isotopes– in periodic table it is a decimal value
• Calculation of Element Atomic Mass– (isotope mass)x(abundance) = mass contribution– add mass contributions of all isotopes– resulting sum is the average atomic mass
Updated October 2006Updated October 2006Created by C. IppolitoCreated by C. Ippolito
September 2006September 2006
MoleMole
• the mole is a fixed amount of particles– 1 mole = 6.022 x 1023 pieces– this number is N or Avogadro’s Number
• named in honor of an Italian chemist
• the concept of the mole allows us to set up a relationship between the immeasurable masses of atoms (in amu) and measurable amounts of a substance (in grams)– 1 mole of amu’s = 1 gram