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Chapter 6: The Periodic Table

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1 Chapter 6: The Periodic Table
6.1: Development of the Modern Periodic Table

2 Antoine Lavoisier Late 1700’s
33 elements (known at time) organized in four categories Category Elements (Old English Names) Gases Light, heat, dephlogisticated air, phlogisticated gas, inflammable air Metals Antimony, silver, arsenic, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdena, nickel, gold, platina, lead, tungsten, zinc Nonmetals Sulphur, phosphorus, pure charcoal, radical muriatique, radical fluorique, radical boracique Earths Chalk, magnesia, barote, clay, siliceous earth

3 Lothar Meyer/Dmitri Mendeleev
Mid-late 1800’s Demonstrated a connection between atomic mass and elemental properties Arranged elements with similar chemical properties horizontally Mendeleev is given more credit because he published first

4 Henry Moseley Early 1900’s Realized arranging the elements by atomic mass was not the best way – some elements ended up in columns with elements of different properties Discovered atoms have a unique number of protons (the atomic number) Arranged elements in order of increasing atomic number, which resulted in a periodic pattern of properties

5 Modern Periodic Table Groups/Families = vertical columns
Periods = horizontal rows

6 (Z)

7 Metalloids – along step line (except for Aluminum)

8 Properties of Metals Conduct heat and electricity
Malleable (can be hammered into thin sheets) Ductility (can be pulled into wires) Lustrous (shiny) appearance Almost all metals are solids at normal temperatures

9 Properties of Non-Metals
Generally lack properties that characterize metals Show more variation in properties than metals do Many are gaseous at normal temperatures

10 Classification of the elements
Section 6.2 Classification of the elements

11 6.2: Organizing the Elements by Electron Configuration
Valence electrons Electrons in the outermost principal energy level Number of valence electrons correspond to the representative elements group number (Group 1 has 1 valence electron, Group 2 has 2 valence electrons, Group 13 has 3 because it is the 3rd representative group, etc) Energy level of valence electrons correspond to the period number (Period 4 valence electrons are in the 4th energy level and so on…)

12 The s-, p-, d-, and f-Block Elements
We saw these with our little “cheat sheets” This shows which sublevel is being filled

13 Section 6.3 Periodic trends

14 PERIODIC TREND QUIZ 1)What group is the: Noble Gases Alkali Metals
Halogens Transition Metals 2)Identify the # of valence electrons for each group/family. 3)An element with an acquired (+) or (-) charge is termed an _____.

15 QUIZ CONT. 4)Identify what groups represent: S block = P block =
D block = F block = 5) Why do elements “give up” or “take” electrons? Think in terms of outer shell, what is this outer shell called?

16 What are Periodic Trends?
Many properties of the elements change in a predictable way, based on their location in the periodic table We will look at the following properties: Atomic radius Ionic radius Ionization energy – the energy req’d to remove an electron from a gaseous atom Electronegativity – ability of an atom to attract electrons in a chemical bond

17 Atomic Radius Trends within periods Trends within groups
Decrease in atomic radius as you move from left to right across a period Trends within groups General increase in atomic radius as you move down a group

18 Ionic Radius An ION is an atom or bonded group of atoms that has a positive or negative charge When atoms lose electrons and become positive ions, they always become smaller When atoms gain electrons and become negative ions, they become larger

19 Ionic Radius (cont’d) Trends within periods (see Fig 6.14)
Generally, as you move from left to right across a period, the size of the positive ions decrease Then, beginning in group 15 or 16, the size of the much-larger negative ions also gradually decreases Trends within groups As you move down a group, ionic size gradually increases

20 Ionization Energy Trends within periods Trends within groups
Values of first ionization energies generally increase as you move from left to right across a period. Trends within groups First ionization energies generally decrease as you move down a group

21 The Octet Rule Atoms tend to gain, lose, or share electrons in order to acquire a full set of eight valence electrons Exception: Hydrogen does not want 8 valence electrons  it will usually give up it’s one electron to make a positive ion

22 Electronegativity Electronegativity values range from 0.7 to 3.98
Fluorine is the most electronegative atom (3.98) Francium is the least electronegative atom (0.70) Many periodic tables list electronegativity values as well

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