1. The Periodic Table History, Organization and Trends

2. Lavoisier, Dobereiner, & Newlands 1790- Lavoisier, 23 elements 1870- Dobereiner, triads, 70 elements 1864- John Newlands, Law of Octaves

3. Dimitri Mendeleev (1834-1907) A Russian chemist who in 1869 published an organized scheme for the elements called the Periodic Table. The elements were arranged in ascending order of atomic mass and also by properties. He was able to predict the properties of undiscovered elements because of their placement in the periodic table. (gallium, scandium, germanium) 1875 1886

4. Henry Mosely (1887-1915) Henry Moseley rearranged the elements in 1913 by ascending order of atomic number.

5. The Modern Periodic Table Periodicity- the tendency to recur at regular intervals Periodic Law: The properties of the elements repeat periodically when the elements are arranged in increasing order by their atomic numbers.

6. Modern PT Organization Groups/ families -vertical columns (similar properites) Periods- horizontal rows Representative elements- Group “A” Transition elements- Group “B” Metals- LEFT Nonmetals- RIGHT Metalloids- On LINE

7. Groups of elements Metals  Alkali  Alkaline Earth  Transition  Inner transition Nonmetals  Halogens  Noble gases Hydrogen is a nonmetal

8. Properties of Metals Solid High melting point Shiny, luster Good conductors of heat and electricity Malleable Ductile Few valence electrons Reacts by giving up electrons Main group metals are highly predictable, transition metals are not.

9. Alkali metals - group 1, 1 valence electron, highly reactive so not found free in nature, reacts with water to give off hydrogen gas, very soft Alkali earth metals – group 2, 2 valence electrons, reactive and not found free in nature, reacts some with water, fairly hard Transition metals – valence electrons vary, some are unreactive to water, some are found free in nature Lanthanide series – also called the rare earth elements, part of the inner transition elements, unpredictable, natural abundance on Earth is less than 0.01% Actinide series – part of the inner transition elements, all are radioactive, unpredictable

10. Properties of Nonmetals Brittle if solid, many are gases Dull Poor conductor of heat, does not conduct electricity Seven diatomic gases-H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 3-8 valence electrons Reacts by taking electrons from other atoms More reactive nonmetals are at top of group

11. Halogens- group 17, 7 valence electrons, reacts by taking electrons from other atoms Noble gases- group 18, 8 valence electrons, inert gases, monatomic gases, most do not react with other elements * Hydrogen is considered a nonmetal

12. Metalloids Has properties of metals and nonmetals Semiconductors

13. Valence Electrons Group “A” number tells valence electrons

14. 6.3 Trends

15. Atomic Radius How Big is the atom?  Group Trend – decreases left to right  Period trend- increases top to bottom

16. Ionic Radius How big is the ion?  Group trend- Increases top to bottom (note metalloid line)  Period trend – decreases to metalloid line, jumps up, then decreases again Ion- an atom or a bonded group of atoms that has a positive or negative charge

17. Ionization Energy How hard is it to remove 1 electron?  Group Trend- decreases top to bottom  Period Trend- increases left to right Octet rule- atoms gain, lose or share electrons to acquire a full set of valence electrons

18. Electronegativity How hard does the atom pull on shared electrons?  Group Trend- Decreases top to bottom  Period Trend- Increases left to right