IIIIII Ch. 5 - The Periodic Table & Periodic Law I. Development of the Modern Periodic Table (p )

A. Mendeleev zDmitri Mendeleev (1869, Russian) yOrganized elements by increasing atomic mass yElements with similar properties were grouped together yThere were some discrepancies

Let’s look for similarities in this to our current model yWhat is with the element boxes with question marks?

A. Mendeleev zDmitri Mendeleev (1869, Russian) yPredicted properties of undiscovered elements

A few more predictions…

B. Moseley zWhy could most of the elements be arranged in order of increasing atom mass but a few could not? zHenry Moseley (1913, British) yOrganized elements by increasing order according to nuclear charge or atomic number yResolved discrepancies in Mendeleev’s arrangement yThis is the way the periodic table is arranged today!

The Periodic Law zThe Physical and Chemical properties of the elements are periodic functions of their atomic numbers. zWhen the elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals.

C. Modern Periodic Table zGroup (Family) zPeriod

1. Groups/Families zVertical columns of periodic table zNumbered 1 to 18 from left to right zEach group contains elements with similar chemical properties

2. Periods zHorizontal rows of periodic table zPeriods are numbered top to bottom from 1 to 7 zElements in same period have similarities in energy levels, but not properties

zMain Group Elements zTransition Metals zInner Transition Metals 3. Blocks

Lanthanides - part of period 6 Actinides - part of period 7 Overall Configuration

IIIIII II. Classification of the Elements (pages ) Ch. 6 - The Periodic Table

A. Metallic Character zMetals zNonmetals zMetalloids

1. Metals zGood conductors of heat and electricity zFound in Groups 1 & 2, middle of table in 3-12 and some on right side of table zHave luster, are ductile and malleable

a. Alkali Metals zGroup 1 z1 Valence electron zVery reactive* zElectron configuration yns 1 zForm 1 + ions zCations yExamples: Li, Na, K *Chemical Property

A special note about Hydrogen zHydrogen has an electron configuration of ns 1 zHydrogen DOES NOT share the same properties as the Alkali metals zHydrogen is unique in its properties and so it is placed apart from the rest of the group

b. Alkaline Earth Metals zGroup 2 zReactive* (not as reactive as alkali metals) zElectron Configuration yns 2 zForm 2 + ions zCations yExamples: Be, Mg, Ca, etc * Chemical Property

c. Transition Metals zGroups zReactive* (not as reactive as Groups 1 or 2), can be free elements zElectron Configuration yns 2 (n-1)d x where x is column in d-block zForm variable valence state ions zCations yExamples: Co, Fe, Pt, etc * Chemical Property

2. Nonmetals zNot good conductors zFound on right side of periodic table – AND hydrogen zUsually brittle solids or gases

a. Halogens zGroup 17 (7A) zVery reactive* zElectron configuration yns 2 np 5 zForm 1 - ions – 1 electron short of noble gas configuration zAnions yExamples: F, Cl, Br, etc * Chemical Property

b. Noble Gases zGroup 18 zUnreactive*, inert, “noble”, stable zElectron configuration yns 2 np 6 full energy level zHave a 0 charge, no ions zExamples: He, Ne, Ar, Kr, etc * Chemical Property

A special note about Helium zHelium has an electron configuration like the Alkaline Earth metals - ns 1 zYet, Helium is a part of the Noble Gases because its highest occupied energy level is filled by two electrons. zHelium possess chemical stability, the unreactive characteristic of the Noble Gases zBy contrast, the Alkaline Earth metals have so special stability – their highest energy level is yet not full (empty p sublevels).

3. Metalloids zSometimes called semiconductors zForm the “stairstep” between metals and nonmetals zHave properties of both metals and nonmetals zExamples: B, Si, Sb, Te, As, Ge, Po, At

B. Chemical Reactivity zAlkali Metals zAlkaline Earth Metals zTransition Metals zHalogens zNoble Gases

C. Valence Electrons zValence Electrons ye - in the outermost energy level zGroup #A = # of valence e - (except He) 1A 2A 3A 4A 5A 6A 7A 8A

C. Valence Electrons zValence electrons = yelectrons in outermost energy level zYou can use the Periodic Table to determine the number of valence electrons zEach group has the same number of valence electrons 1A 2A 3A 4A 5A 6A 7A 8A

D. Lewis Diagrams zAlso called electron dot diagrams zDots represent the valence e - zEx: Sodium zEx: Chlorine Lewis Diagram for Carbon, Calcium and Oxygen? Cl