the periodic table

THE PERIODIC THE PERIODIC TABLETABLEUnit 9Unit 9

ChemistryChemistry

LangleyLangley

*Corresponds to Chapter 6 in the Prentice Hall Chemistry Book

HISTORYHISTORY

PROBLEMPROBLEM By 1860, 60 elements had been discoveredBy 1860, 60 elements had been discovered The element symbols, properties, and atomic The element symbols, properties, and atomic

numbers were published in a booknumbers were published in a book Scientists wanted an easier system to organize the Scientists wanted an easier system to organize the

elementselements Since different chemists used different isotopes, all Since different chemists used different isotopes, all

chemists had different masses recorded for the chemists had different masses recorded for the same elementsame element

First International Congress of Chemists met in First International Congress of Chemists met in 1860 to set the atomic mass for all 60 elements and 1860 to set the atomic mass for all 60 elements and to set the properties of each elementto set the properties of each element

DIMITRI MENDELEEVDIMITRI MENDELEEV

Russian chemistRussian chemist In the process of writing a book in 1860In the process of writing a book in 1860 Decided to include a way to organize the elements in Decided to include a way to organize the elements in

his bookhis book Began by placing all of the element names on note Began by placing all of the element names on note

cards and listing their properties underneath the namecards and listing their properties underneath the name Started moving note cards around and organizing the Started moving note cards around and organizing the

elements by different propertieselements by different properties When note cards were organized in increasing atomic When note cards were organized in increasing atomic

MASS, noticed that other properties started appearing MASS, noticed that other properties started appearing at regular intervals (Ex: every 8th element was at regular intervals (Ex: every 8th element was unreactive, every 9th element reacted with water)unreactive, every 9th element reacted with water)

Named his table periodicNamed his table periodic Periodic – repeating patternPeriodic – repeating pattern

IODINE/TELLURIUMIODINE/TELLURIUM

Find Iodine and Tellurium on the periodic tableFind Iodine and Tellurium on the periodic table What do you notice about their mass?What do you notice about their mass? When I and Te are put in the correct order of When I and Te are put in the correct order of

mass, then their properties don’t fit with their mass, then their properties don’t fit with their columnscolumns

Mendeleev decided that the mass must have Mendeleev decided that the mass must have been recorded wrong, so he put I and Te been recorded wrong, so he put I and Te where they fit based on their properties instead where they fit based on their properties instead of massof mass

BLANK SPACESBLANK SPACES

Mendeleev left empty spaces in his tableMendeleev left empty spaces in his table Empty spaces were for elements that he Empty spaces were for elements that he

thought had not yet been discoveredthought had not yet been discovered Based on where the empty spaces were, Based on where the empty spaces were,

Mendeleev predicted what the mass of the Mendeleev predicted what the mass of the elements and the properties of the elements and the properties of the undiscovered elements would beundiscovered elements would be

Correctly predicted these masses and Correctly predicted these masses and properties for Sc, Ga, and Geproperties for Sc, Ga, and Ge

HENRY MOSELEYHENRY MOSELEY

British chemistBritish chemist Decided to fix the problems with Mendeleev’s tableDecided to fix the problems with Mendeleev’s table Rearranged elements according to atomic NUMBERRearranged elements according to atomic NUMBER Solved the Iodine/Tellurium problemSolved the Iodine/Tellurium problem Created periodic lawCreated periodic law Periodic law – the physical and chemical properties of Periodic law – the physical and chemical properties of

the elements are a function of their atomic numbersthe elements are a function of their atomic numbers (in simple terms: when elements are put in order of atomic (in simple terms: when elements are put in order of atomic

number, then they fit into a certain column that has certain number, then they fit into a certain column that has certain characteristics like reacts with water, etc) characteristics like reacts with water, etc)

FAMILIES OF ELEMENTSFAMILIES OF ELEMENTS

Groups/Families:Groups/Families: Vertical columns on the periodic table, number from left Vertical columns on the periodic table, number from left

to rightto right Rows/Periods:Rows/Periods:

Left to right on the periodic table, number from top to Left to right on the periodic table, number from top to bottombottom

The period number is also the energy level (ring) numberThe period number is also the energy level (ring) number Example: Na is on period 2, Na has 2 energy levels/ringsExample: Na is on period 2, Na has 2 energy levels/rings

Valence Electrons:Valence Electrons: Electrons on the outer energy levelElectrons on the outer energy level Every element is trying to get to either 0 or 8 valence Every element is trying to get to either 0 or 8 valence

electronselectrons

GROUP 1-ALKALI METALSGROUP 1-ALKALI METALS

All have one valence electronsAll have one valence electrons Only hydrogen is not classified as an alkali Only hydrogen is not classified as an alkali

metalmetal Characteristics of Alkali metals:Characteristics of Alkali metals:

React vigorously with non metalsReact vigorously with non metals Most reactive of all METALS (because they only Most reactive of all METALS (because they only

have 1 valence electron to get rid of and reach the have 1 valence electron to get rid of and reach the magic number of 0)magic number of 0)

Too reactive to be found free in natureToo reactive to be found free in nature React violently with waterReact violently with water Have a silvery appearanceHave a silvery appearance Soft enough to cut with a knifeSoft enough to cut with a knife

GROUP 2-ALKALINE GROUP 2-ALKALINE EARTH METALSEARTH METALS

All have 2 valence electronsAll have 2 valence electrons Harder and denser than group 1 but not Harder and denser than group 1 but not

as reactive (they have 2 valence as reactive (they have 2 valence electrons to lose and get to 0)electrons to lose and get to 0)

Still too reactive to be found free in Still too reactive to be found free in naturenature

Characteristics of Alkaline Earth:Characteristics of Alkaline Earth: Many compounds in the Earth’s crust Many compounds in the Earth’s crust

contain calciumcontain calcium Compounds in seawater contain magnesiumCompounds in seawater contain magnesium

GROUPS 3-12-GROUPS 3-12-TRANSITION METALSTRANSITION METALS

Not as reactive as groups 1 and 2Not as reactive as groups 1 and 2 Most have 2 valence electronsMost have 2 valence electrons Characteristics of Transition Metals:Characteristics of Transition Metals:

Many are found free in nature (Au, Cu, Ag, Many are found free in nature (Au, Cu, Ag, Pd)Pd)

Copper is used in wire because it is a good Copper is used in wire because it is a good conductor of electricityconductor of electricity

Tungsten has the highest melting point of all Tungsten has the highest melting point of all metals that is why it is used as the filaments metals that is why it is used as the filaments for light bulbsfor light bulbs

P-BLOCK ELEMENTSP-BLOCK ELEMENTS

Has 8 metals to the left of the zigzag line (Al, Has 8 metals to the left of the zigzag line (Al, Ga, In, T, Sn, Pb, Bi, Po)Ga, In, T, Sn, Pb, Bi, Po) Harder and denser than group 2 but less so than Harder and denser than group 2 but less so than

transition metalstransition metals Most found in natureMost found in nature

8 metalloids on the zigzag line (B, Si, Ge, As, 8 metalloids on the zigzag line (B, Si, Ge, As, Sb, Te, Po, At)Sb, Te, Po, At) Properties of both metals and nonmetalsProperties of both metals and nonmetals Semi-conductorsSemi-conductors Brittle solidsBrittle solids

The rest are non-metals to the right of the The rest are non-metals to the right of the zigzag linezigzag line

GROUP 17-HALOGENSGROUP 17-HALOGENS

7 valence electrons7 valence electrons Most reactive of the NON-METALS (only Most reactive of the NON-METALS (only

need one electron to reach the magic need one electron to reach the magic number of 8)number of 8)

Fluorine is the most reactive of all Fluorine is the most reactive of all elementselements

When nonmetal combines with a metal, it When nonmetal combines with a metal, it produces a salt (Na + Cl produces a salt (Na + Cl NaCl) NaCl)

GROUP 18-NOBLE GASESGROUP 18-NOBLE GASES

8 valence electrons8 valence electrons Helium is the exception it only has 2 valence Helium is the exception it only has 2 valence

electrons and its magic numbers are 0 and 2electrons and its magic numbers are 0 and 2 Least reactive of all elements (already have the Least reactive of all elements (already have the

magic number of 8 valence electrons)magic number of 8 valence electrons) Full outer energy level so no need to form Full outer energy level so no need to form

compoundscompounds

RARE EARTH METALSRARE EARTH METALS

LANTHANOIDSLANTHANOIDS Elements 58-71Elements 58-71 2 valence electrons2 valence electrons Shiny metalsShiny metals Not actually rare, Not actually rare,

most are readily most are readily availableavailable

ACTINOIDSACTINOIDS Elements 90-103, 2 Elements 90-103, 2

valence electronsvalence electrons Elements 90-92 are Elements 90-92 are

naturally occurringnaturally occurring Elements 93 – 103 Elements 93 – 103

are man-made are man-made (synthetic)(synthetic)

Most are radioactiveMost are radioactive

VALENCE ELECTRONSVALENCE ELECTRONS

Could always write out the noble gas configuration and Could always write out the noble gas configuration and find the valence electronsfind the valence electrons

OR use this trick:OR use this trick: Group 1 has 1 valence electronGroup 1 has 1 valence electron Group 2 has 2Group 2 has 2 Groups 3-12 have 2Groups 3-12 have 2 Group 13 has 3Group 13 has 3 Group 14 has 4Group 14 has 4 Group 15 has 5Group 15 has 5 Group 16 has 6Group 16 has 6 Group 17 has 7Group 17 has 7 Group 18 has 8Group 18 has 8

Caution: this trick only tells you valence electrons, not Caution: this trick only tells you valence electrons, not TOTAL electronsTOTAL electrons

PERIODIC TRENDSPERIODIC TRENDS

Atomic Number: # of protons in the Atomic Number: # of protons in the nucleusnucleus Trends: Trends:

Increases across a periodIncreases across a period Increases down a groupIncreases down a group

Atomic Radius: Size of an atomAtomic Radius: Size of an atom Trends:Trends:

Decreases across a periodDecreases across a period Increases down a groupIncreases down a group


Ionization Energy: Energy required to Ionization Energy: Energy required to remove an electron from an atomremove an electron from an atom Trends:Trends:

Increases across a periodIncreases across a period Decreases down a groupDecreases down a group

Electron Affinity: How badly an atom Electron Affinity: How badly an atom wants electronswants electrons Trends:Trends:



Electronegativity: Ability of an atom to Electronegativity: Ability of an atom to attract electronsattract electrons Trends:Trends:



Using trends with groups of elements: Rank the Using trends with groups of elements: Rank the following elements from smallest (1) to largest following elements from smallest (1) to largest (4) in terms of atomic size: Be, He, Ca, Au.(4) in terms of atomic size: Be, He, Ca, Au. Step One: Step One:

Find all 4 elements on the periodic table and place your Find all 4 elements on the periodic table and place your finger on each one.finger on each one.

Step Two:Step Two: Move from left to right across the periodic table using the Move from left to right across the periodic table using the

trend for atomic size (decreases across). You only have to trend for atomic size (decreases across). You only have to use the trend for up and down if you get to a point where use the trend for up and down if you get to a point where you have 2 elements that are in the same column.you have 2 elements that are in the same column.

Step Three:Step Three: Rank the elements from 1 to 4 as you move across the Rank the elements from 1 to 4 as you move across the

table.table.


Example 2: Rank N, O, S, and C from Example 2: Rank N, O, S, and C from smallest (1) to largest (4) in terms of smallest (1) to largest (4) in terms of electron affinity.electron affinity.

the periodic table

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