Chemistry elements 1

• List of units in this learning guide

  • Blackboard - Basic Mathematics in Chemistry
  • Ch 1 - Scientific Measurements
  • Ch 0, 2 - A very Brief History of Chemistry and Elements, Compounds and the Periodic Table
  • Ch 3 - The Mole and Stoichiometry
  • Ch 4, 5 - Molecular View of Reactions in Aqueous Solutions and Oxidation-Reduction Reactions
• Learning outcomes


  • Know the names and symbols of all the main group and transition elements of the periodic table up to element 54 (Xenon) by heart
  • Classify an element as a metal, non-metal or metalloid
  • Explain the meaning of the concepts group and period as well as the letters A and B with reference to the periodic table
  • Identify the main-group or representative elements and transition elements
  • Identify the alkali metals, alkaline earth metals, halogens, noble gases, lanthanides and actinides
  • Define, compare and differentiate among element, molecule and compound, ionic and covalent bonds, molecular and ionic substances
  • Discuss the different methods used to represent molecules and compounds such as molecular, empirical and structural formulae
  • Predict the charge of an ion and know what the influence of ion formation (cat- or anion) is
  • Know all the rules for naming and be able to apply them to write formulas from names or names from formulas for ionic compounds, binary molecular compounds, acids and their corresponding anions, and hydrated ionic compounds

  
• The periodic table summarizes periodic properties of elements

  
• Early versions of periodic tables

  1. Arranged by increasing atomic mass

  2. Mendeleev (Russian) and Meyer (German) in 1869 noted repeating (periodic) properties

  
• Periodic law


  When the elements are arranged in order of increasing mass, certain sets of properties recur periodically

  
• Mendeleev organized the known elements in a table, arranging the rows so that elements with similar properties fall in the same vertical columns
• Mendeleev's table contained some gaps, which allowed him to predict the existence (and even the properties) of yet undiscovered elements
• Modern periodic table


  • Arranged by increasing atomic number (Z)
  • Rows called periods
  • Columns called groups or families
  • Identified by numbers 1 – 18 standard international or 1A – 8A longer columns and 1B – 8B shorter columns (North America)
• Representative/Main Group Elements


  • Alkali Metals (Group 1A)
  • Alkaline Earth Metals (Group 2A)
  • Halogens (Group 7A)
  • Noble Gases (Group 8A)
• Alkali Metals


  • Very reactive
  • All are metals except for H
  • Tend to form +1 ions
  • React with oxygen
  • Form compounds that dissolve in water
  • Yield strongly caustic or alkaline solution (Na2O)
• Alkaline Earth Metals


  • Reactive
  • Tend to form +2 ions
  • Oxygen compounds are strongly alkaline (MgO)
  • Many are not water soluble
• Halogens


  • Reactive
  • Form diatomic molecules in elemental state
  • 2 gases – F2, Cl2
  • 1 liquid – Br2
  • 2 solids – I2, At2
  • Form –1 ions with alkali metals—salts (e.g. NaF, NaCl, NaBr, and NaI)
• Noble Gases


  • Inert—very unreactive
  • Only heavier elements of group react and then very limited
  • Don't form charged ions
  • Monatomic gases (e.g., He, Ne, Ar)
• Transition Elements


  • All are metals
  • In center of table
  • Begin in fourth row
  • Tend to form ions with several different charges (e.g. Fe2+ and Fe3+, Cu+ and Cu2+, Mn2+, Mn3+, Mn4+, Mn5+, Mn6+, and Mn7+)
• Inner Transition Elements


  • Lanthanide elements (elements 58 – 71)
  • Actinide elements (elements 90 – 103)
  • All actinides are radioactive
• Elements classified as metals, nonmetals, or metalloids

  • Metals (left-hand side of periodic table)
  • Nonmetals (upper right-hand corner of periodic table)
  • Metalloids (diagonal line between metals and nonmetals)

  
• Properties of Metals


  • Metallic luster
  • Malleable
  • Ductile
  • Hardness (some hard, some soft)
  • Conduct heat and electricity
  • Solids at room temperature
  • Melting points (mp) > 25 °C
  • Chemical reactivity varies greatly
• Properties of Nonmetals


  • Brittle
  • Pulverize when struck
  • Insulators (non-conductors of electricity and heat)
  • Some inert, some reactive
• Properties of Metalloids


  • Between metals and nonmetals
  • Metallic shine
  • Brittle like nonmetal
  • Semiconductors (conduct electricity but not as well as metals)
• Molecules


  • Atoms combine into compounds
  • Discrete particles each composed of two or more atoms
• Chemical Formulas


  • Specify composition of substance
  • Chemical symbols represent atoms of elements present
  • Subscripts represent relative numbers of each type of atom
• Atoms


  Tiny particles that make up matter
• Atoms


  • Indestructible
  • Rearrange but do not break apart in chemical reactions
• Atoms of different elements

  • Differ in mass and other properties
• Atoms in a given compound

  • Always present in the same fixed numerical ratio
• All molecules of a compound are alike and contain atoms in the same numerical ratio
• Mass of oxygen is 8 times the mass of hydrogen in water
• Law of definite proportions


  All samples of a given compound have the same proportions of their constituent elements
• Two samples of CO2 decomposed into their constituent elements have the same ratios of oxygen to carbon
• Law of multiple proportions

  When two elements form two different compounds, the masses of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers
• Formulas and structures are backed by extensive experimentation
• Homogeneous mixture/solution


  Uniform mixing of substances
• Heterogeneous mixture


  Two or more phases