malone and dolter - basic concepts of chemistry 9e1 chapter 4 the periodic table and chemical...

Malone and Dolter - Basic Concepts of Chemistry 9e

1

Chapter 4Chapter 4

The Periodic Table and The Periodic Table and Chemical NomenclatureChemical Nomenclature


2

Setting the Stage – The Periodic Table

The periodic table is the map of chemical behavior of the elements

Chemical nomenclature is the vocabulary of chemistry – how we name compounds and write formulas


3

Setting a Goal - Part ARelationships Among the Elements and the Periodic Table

You will be able to explain the significance of the periodic table, its origins, and how different properties of an element can be predicted by its location on the table


4

Objective for Section 4-1 Describe the origins of the

periodic table


5

4-1 The Origin of the Periodic Table

The elements are grouped in several categories, according to properties and therefore according to position in the periodic table.

Two major groupings are metals and nonmetals


6

Professor’s Little Joke


7

The Origin of the Periodic Table

John Newlands, Dmitri Mendeleev and Lothar Meyer were the main originators of the periodic table of elements


8

The Modern Periodic Table of Elements


9

Metals

Tend to form cations in ionic compounds Are ductile (can be drawn into wires) Malleable (can be pounded into sheets) Readily conduct electricity and heat See Figure 4-1


10

Nonmetals

Tend to form anions in ionic compounds

Are generally soft solids or gases See Figure 4-2


11

Classes of metals

Active metals very reactive to air and water include lithium, potassium and sodium

Noble metals very unreactive gold, silver and copper


12

Metalloids

Have properties intermediate between metals and nonmetals

Their most important current use is as semiconductors


13

Objective for Section 4-2

Using the periodic table, identify a specific element as a metal or a nonmetal and give its period, group number, the name of the group if appropriate, and its physical state


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4.2 – Using the Periodic Table

Locating the main types of elements Metals are found to the left of the periodic

table Nonmetals are found to the right of the

periodic table Metalloids are located along the metal-

nonmetal dividing line


15

The Periodic Table

Elements were originally arranged in columns by chemical properties, then atomic weight

The modern periodic table has the elements arranged by atomic number

The periodic law - the properties of the elements are periodic (cyclically repeating) functions of their atomic number


16

Periodic Divisions

Period Horizontal rows in the periodic table Properties of elements across a period change

dramatically Each period ends with a member of the noble

gas family Group

Vertical columns in the periodic table Properties of elements in the same group are

similar


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Main Group Elements

Group IA - alkali metals Group IIA - alkaline earths Group VIA - chalcogens Group VIIA - halogens Group VIIIA - noble gases

* These are the groups with specific names


18

Transition Elements

Group B elements Metals with multiple oxidation states Includes noble or coinage metals (Cu,

Ag, Au) Platinum group metals (Ru, Rh, Pd, Os,

Ir, Pt) Structural metals such as Fe and Cr


19

Inner transition elements

Lanthanides Often called rare earth elements due to

the difficulty in isolating pure samples Chemical properties almost identical

Actinides Radioactive elements, many synthetic


20

Physical States of Elements

Reference condition is 1 atmosphere of pressure and 25 °C

Gaseous elements - H2, N2, O2, F2, Cl2, noble gases

Liquid elements - Hg, Br2 Others? All other elements are solids Other molecular nonmetals are not

diatomic and may have several forms (allotropes)


21

Periodic Table – Summary ChartRepresentative elements

H He

Nob

lega

ses

Alk

alim

eta

ls

Alk

alin

eea

rth

met

als

Transition metals

Ch

alog

ens

Hal

oge

ns

Inner transition elements

Lanthanides

Actinides


22

Setting a Goal – Part BThe Formulas and Names of Compounds

You will learn how to systematically name various types of molecular and ionic compounds and determine the formulas of compounds from the names


23


Write and name ionic compounds involving a metal and a nonmetal using IUPAC conventions


24

A Little Joke on Nomenclature

A research chemist walked into a pharmacy

and asks, “Do you have (5,6)-7,8-didehydro-4,5-

epoxy-3-methoxy-17-methylmorphinan-6-ol?”

The pharmacist scratched her head and

said, “Do you mean codeine?”

“That’s it!”, said the chemist, “I can

never remember that word!”


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4-3 Naming and Writing Formulas of Metal-Nonmetal Binary Compounds

Binary compounds are composed of two different elements

Two types of metal-nonmetal binary compounds Metals exhibiting only one oxidation state

forming a compound with a nonmetal Metals exhibiting two or more oxidation states

forming a compound with a nonmetal


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Metals with only one Oxidation State

Groups of metals with only one common oxidation state alkali metals +1 alkaline earths +2 Zn +2 Al +3

All other metals can exhibit more that one oxidation state


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Anions in Negative Oxidation States

Nonmetallic anions usually exhibit one negative oxidation state Halogens -1 Chalcogens -2 N, P -3 C -4


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Forming Ionic Compounds

Metal and nonmetal combine to neutralize charge

Such compounds are often termed salts

Individual anions and cations do not exist separately – always found together


29

Cross-Charge Method

Consider - Al3+, O2-

Cross multiply charges 2 Al3+ + 3 O2- = Al2O3


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Naming Binary Compounds

Use name of metal with no changes Change the name of the anion by

taking the “stem” and add the suffix -ide

Examples NaCl - sodium chloride MgCl2 - magnesium chloride


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Metals with Multiple Oxidation States

Two systems: Stock and “Classical” Stock system

Metal name and the oxidation state in Roman numbers in parentheses

Fe2+ = iron(II)

Form compound by balancing charge of metal with correct number of nonmetals

CoCl3 = cobalt(III) chloride


32

Classical Nomenclature

Metals in multiple oxidation states usually have one or two common oxidation states

First row transition metals are +2 and +3 (except Cu2+ and Cu+)

Use -ous suffix for lower common oxidation state

Use -ic suffix for higher common oxidation state


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Examples

CoCl3 - cobaltic chloride

NiCl2 - nickelous chloride For metals with Latin names, use the

Latin names CuCl - cuprous chloride FeBr3 - ferric bromide


34


Write and name compounds containing polyatomic ions using IUPAC conventions


35

4-4 Naming and Writing Formulas of Compounds with Polyatomic Ions

Polyatomic ions (listed in Table 4-2) act as monoatomic ions in most circumstances

Most polyatomic ions are oxyanions, but some are simply polyatomic species with trivial names

Treat the polyatomic ion as a monoatomic ion in the cross-charge method for formula


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Oxyanions

Anions composed of oxygen and another element

Other elements can be a metal or a nonmetal

Examples SO4

2-, NO2-, PO4

3-, MnO4-, CrO4

2-


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Naming Oxyanions

Need common oxidation states most common oxidation state for

nonmetals is the group number (except for the halogens)

next most common oxidation state is the group number minus one

Use -ate suffix for higher oxidation state and -ite suffix for next higher oxidation state


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Examples

SO42- - sulfate

SO32- - sulfite

NO3- - nitrate

NO2- - nitrite

Salts with these oxyanions Na2SO4 - sodium sulfate

KNO3 - potassium nitrate


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Salts Compounds formed by combining a

cation and an anion in the proper ratio to yield a neutral species

Examples include NaCl, K2SO4, NH4I Often formed by the reaction of a

acid containing the anion and a hydroxide compound containing the cation


40

Examples of Salt Formation Occurring out of Water

2Na + Cl2 2NaCl NH3 + HCl NH4Cl


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Name binary molecular (nonmetal-nonmetal) compounds using proper Greek prefixes


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4-5 Naming Nonmetal-Nonmetal Binary Compounds

Name nonmetal further to the left of the periodic table first with no changes

Name nonmetal further to the right of the periodic table second with the -ide suffix

Use Greek prefixes to indicate the number of each one

Stock system is rarely used in this case since it can yield ambiguous results


43

Greek Prefixes

Number Prefixes

1 mono

2 di

3 tri

4 tetra

5 penta

6 hexa

7 hepta


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Examples

N2O3 – dinitrogen trioxide

N2O5 – dinitrogen pentoxide

CO2 – carbon dioxide

P2O5 – diphosphorus pentoxide

C3O2 – tricarbon dioxide (carbon suboxide)

CO – carbon monoxide


45


Name and write the formulas of acids


46

4-6 Naming Acids

Binary acids Name begins with hydrohydro Then add stem of nonmetal plus -ic-ic End the name with acidacid

Examples HCl - hydrochloric acid H2S - hydrosulfuric acid


47

Oxyacids (see Table 4-6)

Take oxyanion suffix and convert Change -ate to -icic Change -ite to -ousous

Do not use hydro- in the beginning Examples

H2SO4 - sulfuric acid

H2SO3 - sulfurous acid

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