The Periodic Table and Periodic Law

1. The Periodic Table and Periodic Law Chapter 6

2. Section 6.1: Development of the Modern Periodic Table • Late 1790’s- Lavoisier compiled a list of 23 elements known at the time • By 1870- 70 known elements • John Newlands • Arranged elements by increasing atomic mass • Noticed properties repeated every eighth element (periodic) • Law of Octaves

3. Dmitri Mendeleev • Russian • 1st periodic table • Organized elements by properties • Arranged elements by atomic mass • Predicted existence of several unknown elements • Element 101 Mendeleevium (Md)

5. Henry Moseley • 1913-performs experiments to determine the atomic number of the known elements • Afterwards arranges the elements in the periodic table listing them by increasing atomic number instead of by mass

6. Periodic Law When the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties

7. The Modern Periodic Table • Groups- aka families (vertical columns) • Each group is numbered 1-8 followed by the letter A or B • Representative Elements- designated with an A (1A-8A) • Transition Elements- designated with a B (3B-12B) • 18 total groups • elements of any one group have similar physical and chemical properties

8. Periods- horizontal rows • 7 total periods • element properties change as you go across each row • the pattern of properties repeats from one period to the next

9. Classifying the Elements • Three main classifications for the elements • Metals • Nonmetals • Metalloids

10. Metals • Physical Properties • Luster (shininess) • Good conductors of heat and electricity • High density (heavy for their size) • High melting point • Ductile (most metals can be drawn out into thin wires) • Malleable (most metals can be hammered into thin sheets) • Chemical Properties • Easily lose valence electrons • Corrode easily • Alkali Metals- group 1A elements (except hydrogen) • Alkaline Earth Metals- group 2A elements

11. Metals Con’t. • Transition Metals • Group B elements • Inner Transition Metals • Lanthanide- used as phosphors (substances that emit light when struck by electrons) • Actinide

12. Nonmetals • Physical Properties • No luster (dull appearance) • Poor conductor of heat and electricity • Brittle (breaks easily) or gaseous • Not ductile • Not malleable • Low density • Low melting point • Bromine is the only nonmetal liquid at room temperature • Chemical Properties •  Tend to gain valence electrons

13. Nonmetals Con’t • Halogens • Group 7A • Extremely Reactive • Noble Gases • Group 8A • Extremely Unreactive

14. Metalloids • Bordering the stair-step line • Physical Properties • Solids • Can be shiny or dull • Ductile • Malleable • Conduct heat and electricity better than nonmetals but not as well as metals

17. Elements in the same group on the periodic table have similar chemical properties because they have the same valence electron configuration

18. Section 6.3: Periodic Trends • The electron cloud surrounding the nucleus is based on the probability and does not have a clearly defined edge • Atomic size is defined by how closely an atoms lies to a neighboring atom

19. Atomic Radii Trend • Trends within periods • Generally decreases as you move left-to-right across a period (row) • Trends within groups • Generally increases as you move down a group

20. Ionic Radius • An ion is an atom or a bonded group of atoms that has a positive or negative charge • When atoms lose electrons and form positively charged ions, they always become smaller • When atoms gain electrons and form negatively charged ions, they always become larger

21. Lose Electrons  Smaller ionic radii Gain Electrons  larger ionic radii

22. Ionization Energy (I.E.) • Ionization Energy- the energy required to remove an electron from a gaseous atom • 1st Ionization Energy- removes the 1st electron • 2nd Ionization Energy- removes the 2nd electron… and so forth • I.E. is an indication on how strongly an atom’s nucleus holds onto its valence electrons

23. Octet Rule- atoms tend to gain, lose or share electrons in order to acquire a full set of eight valence electrons

24. Octet Rule- atoms tend to gain, lose or share electrons in order to acquire a full set of eight valence electrons • Hydrogen and Helium are exceptions (they’ll be happy with 2 V.E.) • Determines the types of ions likely to form • Elements on the right side tend to gain electrons • Elements on the left side tend to lose electrons

25. Electronegativity • Indicates the relative ability of its atoms to attract electrons in a chemical bond • Noble gases form very few compounds so they are left out • In a chemical bond, the atom with the greater electronegativity more strongly attracts the bond’s electrons

27. In Summary Atomic radius decreases Ionization energy increases Electronegativity increases Atomic radius increases Ionization energy decreases Electronegativity decreases 1A 0 2A 3A 4A 6A 7A 5A

28. Electronegativity Ionization energy Atomic radius Metal Transition metal Anion Periodic law Cation Period Group Electrons Nonmetal Matching Words for Test

29. Homework • Page 174-175 • #29-#38 • #40-#45 • #47-#76