The Periodic Table. Chapter 5. I. History II. Organization III. Periodic Trends

Transcription

1 The Periodic Table Chapter 5 I. History II. Organization III. Periodic Trends

2 I. History P

3 5a: The Periodic Table Material in chapter 5 is critical to understanding chapter 6! Early Organization of the Elements 1889: Johann W. Dobereiner ( ) Organized chemicals into groups called triads (made up of 3) Analysis was flawed because there seemed to be more than 3 types of elements that could fit into each category Credited with grouping elements into families according to similar chemical properties

4 1864- John Newlands John Newlands arranged elements by increasing atomic masses Started with the idea that every 8 th element had similar properties Arranged similar elements into columns Used atomic mass to group elements Law of Octaves 8 groups Credited with the idea that atomic mass and chemical properties are related

5 1869 Dmitri Ivanovich Mendeleev developed the modern periodic table Organized elements by increasing atomic mass Elements with similar properties were grouped together Left spaced between elements to fill in later Predicted properties of undiscovered elements I m a Genius

6 1869 Dmitri Mendeleev (con t.) Identified the category of transition metals Mendeleev s Periodic Law Properties of elements vary with their atomic masses in periodic ways Some problems with Mendeleev s table

7 1912 Henry Mosley Henry Mosley discovered how to count protons in the nucleus Discovered arranging elements by atomic number Fixed Mendeleev s problems Remember: Mendeleev didn t know about protons, nucleus, or atomic number! New Periodic Law : the properties of an element vary with their atomic numbers in a systematic way.

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9 3 Naming Conventions North American Convention (text) Roman numerals above columns # valence e - A = main groups B = transition metals International Union of Pure and Applied Chemistry Convention (classroom) IUPAC the same group responsible for certifying atomic masses and element names numbers the Groups from 1 through 18. European Convention

10 II. Organization Metallic character Metals Nonmetals Metalloids

11 Organization of the Elements Blocks Elements represented by symbols Atomic number upper left Atomic mass under symbol Form columns and rows Columns = Groups Rows = Periods

12 Metallic Character Metals Left side Hard and Lustrous Malleable Ductile Good conductors of heat and energy Nonmetals Far right Soft solids or gases Dull Brittle Good insulators Metaloids Right side Have both metal and non-metal properties

13 Coinage Elements Guess what they are used for????? TO MAKE COINS Group 11 Copper (Cu) Silver (Ag) Gold (Au)

14 Blocks Main group elements (A) Transition metals (B) Inner transition metals Lanthanoids Actinoids

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16 III. Periodic Trends P

17 5b: Periodic Trends Periodic Law: when elements are arranged in order of increasing atomic #, elements with similar properties appear at regular intervals.

18 5b: Periodic Trends Groups or Families Similar valence electrons within a group result in similar chemical properties Alkali Metals Alkali Earth Metals Transition Metals Boron Family Carbon Family Nitrogen Family Oxygen Family Halogens Noble Gases Lanthinoids Actinoids

19 5b: Periodic Trends Atomic and Ionic Radii Measures the electron cloud of atom Atomic radius is the SIZE of atom First Ionization Energy Energy required to remove one e- from a neutral atom Electron Affinity How much an atom wants to gain an e- Melting Point/ Boiling Point Electronegativity The ability of atoms to attract bonding pair of e-

20 Atomic Radii Generally Radii of atoms decrease from left to right in period As electrons added, greater pull on electrons from nucleus (opposing forces) Each new electron is pulled more strongly than the last by ELECTROSTATIC ATTRACTIONS Radii of atoms increase going down groups Due to the addition on new principal energy levels Shielding = core e- block the attraction btw nucleus and VE

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23 Atomic Radii and Ions Cations (+ ions) Smaller than parent atoms Loss of electron(s) Making electron cloud smaller Anions (- ions) Larger than parent atoms Gain electron(s) Make electron cloud larger

24 Positives and Negatives. What do we call the attraction between positive and negative charges? COULOMBIC ATTRATION Based on Coulomb s Law

25 1st Ionization Energy (kj) Ionization Energy First Ionization Energy He Ne Ar Li Na K Atomic Numbe r

26 Ionization Energy First Ionization Energy Increases UP and to the RIGHT

27 Ionization Energy Why opposite of atomic radius? In small atoms, e - are close to the nucleus where the attraction is stronger Why small jumps within each group? Stable e - configurations don t want to lose e -

28 Ionization Energy Successive Ionization Energies Large jump in I.E. occurs when a CORE e - is removed. Mg 1st I.E. 736 kj 2nd I.E. 1,445 kj Core e - 3rd I.E. 7,730 kj

29 Ionization Energy Successive Ionization Energies Large jump in I.E. occurs when a CORE e - is removed. Al 1st I.E. 577 kj 2nd I.E. 1,815 kj 3rd I.E. 2,740 kj Core e - 4th I.E. 11,600 kj

30 Ionization Energy (cont.) More energy is required to pull more and more electrons off of an atom 1 st IE 2 nd IE 3 rd IE. KJ/mol H He Li Be B C N O F Ne Na Mg 737 Ionization 1450 Energies in 7731 kj/mol

31 Examples Which atom has the larger radius? Be or Ba Ba Ca or Br Ca

32 Examples Which atom has the higher 1st I.E.? N or Bi N Ba or Ne Ne

33 Ionization Energy IE important to determine reactivity First Ionization Energy Minimum energy required to remove a neutral atom s outermost electron to form ion IE increases from left to right in period Become more difficult to remove electrons L R Electrons more strongly attracted to nucleus IE decreases in group from top to bottom Outer electrons in higher energy levels and farther from nucleus Outer electrons are shielded from positive charges in nucleus from electrons in lower levels

34 Electron Affinity Increases from left to right Decrease from top to bottom

35 Melting and Boiling Points Highest in the middle of a period! Electronegativity (Linus Pauling) Most important attractive property Ability of an atom to attract a bonding pair of electrons Fluorine MOST electronegative element Increases towards flourine from left and bottom

36 Which atom has the larger radius? Be or Ba Ca or Br Li or S K or O He or Rn (Radon)

37 Which atom has the greater ionization energy? He or Kr B or Ga C o r Pt O or I

38 Which atom has the greater electronegativity? F or B C or O N or As

39 5C Descriptive Chemistry Descriptive Chemistry the study of elements and the compounds they form. Physical Properties Color, Odor, Taste Density Diffusion Phases Chemical Properties Chemical behavior State of electrons Reactivity