The Periodic Table

1. The Periodic Table The Coolest Table in the World

2. The Periodic Table • This is the actual form of the periodic table • The form you usually see is so that less space is taken up This portion of the periodic table is usually placed below

3. The Periodic Table Like this!

4. A History of the Periodic TableDmitri Mendeleev 1869 • name, atomic mass, and physical and chemical properties of each known element on cards. • arranged the elements in rows by increasing atomic mass. • noticed a pattern in the properties of the elements that repeated at regular intervals (periodic). • arranged the elements in columns such that those in the same column would have similar properties

5. A History of the Periodic TableDmitri’s Table • His table had discrepancies. For example, iodine and tellurium. But since they had similar properties, he kept their masses out of order. • He left gaps in his table and correctly predicted the properties of elements that were yet to be discovered based on the properties of the other elements in the column.

6. Dimitri’s Eerie predictions • ekasilicon (germanium) • predicted density = 5.5 g/ml • actual density = 5.35 g/mL • predicted mass = 72 amu • actual mass = 72.49 amu • predicted boiling point = 2935 0C • actual boiling point = 2834 0C SPOOKY

7. A History of the Periodic TableHenry Moseley (1913) • Worked with Rutherford analyzing line spectra of elements. • arranged the elements by increasing atomic number to better fit into patterns. • Mendeleev’s discrepancies disappeared!! Elements were still grouped in columns according to similar properties.

8. The Periodic Law • The basis for the periodic table. • States the the physical and chemical properties of elements are periodic functions of their atomic numbers. • When elements are arranged in order of increasing atomic number, their physical and chemical properties repeat in a predictable, regular pattern. (repeat in a periodic pattern)

9. 8A 1A 7A 6A 3A 5A 4A 2A Today’s Periodic Table • Rows/periods - there are 7 rows, corresponding to the number of energy levels containing electrons in their ground state. • Columns/groups/families - there are 18 columns. Columns 1A-8A (main group elements) correspond to number of valence electrons present in the element. • Three major divisions - metals, semi-metals and non metals.

10. Properties of Major Divisions Metals • lusterous, shiny • typically solids at room temperature (except Hg, Cs) • good conductors of heat and electricity • malleable and ductile • tend to lose electrons easily (form cations)

11. Properties of Major Divisions Nonmetals • do not have a metallic luster • poor conductors of heat and electricity • may be solid, liquid or gas at room temperature (majority are gases) • non malleable, non ductile • tend to gain electrons easily (form anions)

12. Properties of Major Divisions Semi-metals (metalloids) have properties that are intermediate between metals and nonmetals.

13. The ‘s’, ‘p’, ‘d’ and ‘f’ blocks

14. 3 4 5 6 7 8 The Main Group Elements(the ‘s’ and ‘p’ blocks) 2 1 These are the Main group elements. They are the most obvious ones to follow the periodic law • Main group elements have valence electrons that range from 1 to 8 • Same family, same number of valence electrons. That’s why elements in the same family have similar properties - they have the same number of valence electrons!!!!

15. Major Groups of the Periodic Table Scan in heath page 368

16. Properties of the Major Groups 1A alkali metals • Soft, silvery and shiny • Highly reactive; combine vigorously with non metals and react with water to form hydrogen gas. • Are so reactive, are not found as free elements in nature (are always combined with something else!) • One valence electron • Uses - example Cs, used for electronic doors

17. Properties of the Major Groups 2A alkaline earth metals • less reactive than 1A, form bases when react with water (alkaline) • Still too reactive to be found free in nature • harder, denser, higher melting points than 1A • two valence electrons • Uses - Sr in fireworks (remember the flame color?), Mg used in alloys for lightweight aircraft bodies, Ca important for bones, teeth…

18. Properties of the Major Groups D block / transition metals • Good conductors, harder, more dense with higher melting points than s and p block elements (except Hg) • Less reactive than s block metals - some are found in their elemental form in nature (Ag, Au, Cu) • Uses - ‘coinage’ metals due to low reactivity, Ag for photography, W for filaments in light bulbs, Fe mixed with other metals for steel.

19. Properties of the Major Groups 7A halogens • react with alkali metals to form salts (ionic compounds) • Highly reactive and therefore exist as diatomic molecules (F2, Cl2, Br2) • Distinct colors and odors - all are poisonous. • At room temperature, fluorine and chlorine are gases, bromine is a liquid and iodine is a solid. • Seven valence electrons

20. Properties of the Major Groups 8A noble gases • Argon discovered in 1894 - eluded discoverty to due lack of reactivity! • aka ‘rare gases’, make up 1% of atmosphere. • relatively unreactive - inert, stable (so good for lights!) • Have full valence shells - all have eight valence electrons except helium (full with two)