Notes

Outline

Periodic Properties of the Elements

First Periodic Law Of The Elements Proposed by Mendeleev Based on Atomic Weights Mendeleev’s Law-  The properties of the elements are a periodic function of their increasing atomic weights

Periodic Relationships Between Two Variables Sin and cos of an angle vs angle size Moon Phases (time vs moon’s position in space relative to the Earth) Metabolic Rate changes in plants (time vs flowering)

Modern Periodic Law Of The Elements Proposed by Moseley Based on atomic numbers Moseley’s Law- The properties of the elements are a periodic function of their increasing atomic numbers.

T-8.12 Modern Periodic Table

Periods and Groups In The Periodic Table Period-Row of Elements Seven periods Represents a complete cycle for the value of a property to repeat itself Groups-Vertical Rows including elements that are very similar in properties 18 groups

Group Names Group 1 = Alkali Metals Group 2 = Alkali Earth Metals Group 3-12 = Transition State Metals Group 17 = Halogens Group 18 = Noble Gases

Octet Rule The most stable atom will be one that has a completely filled outer valence region(complete octet with the exception of Hydrogen Group 1=lose 1 electron = +1 ion Group 2 = lose 2 electrons = +2 ion Group 13 = lose 3 electrons = +3 ion Group 14 = lose 4 electrons = +4 ion Group 15= gain 3 electrons = -3 ion

Octet Rule (cont) Group 16 = gain 2 electrons = -2 ion Group 17 = gain 1 electron = -1 ion Group 18 = gain 0 electrons = no charge

Atomic Radius Atomic Radius- The distance from the center of an atom and its outermost occupied region

T-8.16 Atomic Radius vs atomic number

Periodic Trend For Atomic Radius Within the Periodic Table the Atomic Radius decreases as we proceed to the right in a period and up within a group Hydrogen is smallest and Francium is the largest atom

T-8.17 Atomic Radii Of Representative Elements

Metallic Strength and Atomic Radius Metals tend to have the largest radii Non-metals tend to have the smallest radii

Ionization Energy First Ionization Energy-Energy required to remove the first electron from an atom Second Ionization Energy- Energy required to remove a second electron from an atom. Be   +   IE1 --àBe +    1s2,2s1  + Be +    +   IE2  --à  Be+2   1s2  +2 Be +2   +   IE3 -à Be +3  1s1  +3 (complete valence region disturbed) IE3 >>>>>>>IE2>IE1

T-76 Some Selected Ionization Energies

Periodic Trends and Ionization Energy Within the Periodic Table Ionization Energy increases as we proceed to the right in a period and up in a group

T-8.18 Ionization Energy vs Atomic Number

Relationship Between Metallic Strength and Ionization Energy Metals tend to have low Ionization Energies Non-metals tend to have high Ionization Energies

Electron Affinitity Electron affinity-Energy released when an atom gains an electron Electron Affinity increases as we proceed to the right in a period and up in a group Metals tend to have low electron affinities Non-metals tend to have high electron affinities

T-59 Electron Affinity Values

Metals Metals-elements whose atoms lose one or more electrons to become positively charged cations Na ---à   Na +   +   e – Ca----à  Ca +2    +    2 e – Al ----à Al +3   +   3 e –

Non-Metals Non-metals-Elements whose atoms tend to gain one or more electrons becoming negatively charged anions F   +   e - -à  Cl – O  +  2e -  -à O –2 N   +  3 e -   -à N –3

Metalloids Metalloid- Element whose atoms may gain or lose one or more electrons depending upon its association with other atoms

Periodic Trends of Metallic , Non-Metallic and Metalloids Within the Periodic Table Metallic properties decrease and Non-Metallic Properties increase as you proceed to the right in a period or up in a group. Flourine is the most non-metallic and Francium is the most metallic

T-60 Periodic Table vs Metallic Properties

T-198 Summary of Periodic Properties