ch 3 periodicity

8/10/2019 Ch 3 Periodicity

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zbeta Bavorova

Assesment statements from

Pearson Baccalaureate HL

Chemistry

Chapter 3eriodicity


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Ch 3.1 The Periodic Table

3. 1. 1. Describe the arrangement of elements in the Periodic Table in order

of increasing atomic number.

The elements are arraned on the basis of the atomic number. The atomic number ro!s to

the riht and do!n.

3. 1. 2. Distinguish between the terms group and period.

Groupsare the columns of the periodic table. "lements in one roup have similar properties.

Periodsare the ro!s of the periodic table.

3. 1. 3. Apply the relationship between the electron arrangement of

elements and their position in the Periodic Table up to Z = 2.

! 3. 1. ". Apply the relationship between the number of electrons in thehighest occupied energy le#el for an element and its position in the Periodic

Table.

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E'ectronegatiity

(Pau'ing)"lectroneativity is very much

related to e0ective nuclear

chare ionization enery and

electron a9nity so the trends are

similar.

"e'ting pointThe meltin point is dependent on the bondin

of the element.

-t is hih for elements in a metallic

bond. Hih for elements in a iant covalent

structure.

Lo! for covalently bound atoms.

-t is more di9cult to provide atoms that are

bound by strong intermo'ecu'ar ,onds!ith

enouh *inetic enery to melt them.

Group

1

(alkali metals):

:eltin point decreases do!n the roup.

As the size of the atom ro!s do!n the roup !hile

the metallic structure is still composed of ,1 ions the

chare density falls sini2cantly and thus the force

holdin the metallic lattice toether is !ea*er.

Group 17 (halogens):

:eltin point increases do!n the roup.

As the size of an atom ro!s do!n the roup the e0ect

of the ;an der


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Ch 3.3 Chemical properties

3. 3. 1. Discuss the similarities and di-erences in the chemical properties of

elements in the same group.

"lements !ithin the same roup have very similar chemical properties because chemical

properties depend on their electron con2uration = and the valence shell of electron !ithinthe same roup is the same.

Ho!ever their properties are not the same. 8or e)ample the reactivity of al*ali metals

increases do!n the roup. This is because of the fallin ionization enery because more

reactions !ill be able to provide enouh enery for ionization/.

3. 3. 2. Discuss the changes in nature* from ionic to co#alent and from basic

to acidic* of the o)ides across Period 3.

-onic compounds are enerally formed bet!een metal and non#metal the o)ides of

elements >a to Al have a giant ionic structure.

Covalent compounds are formed bet!een non#metals the o)ides of P ? and Cl are

mo'ecu'ar coa'ent.

The o)ide of silicon !hich is a metalloid is a giant coa'ent structure.

The ionic character of a compound depends on the di0erence in electroneativity bet!een

its elements the hiher the more ionic/.

The o)ides become more ionic do!n the roup as the electroneativity decreases.

The conductiityof the molten o)ide can be used as a measure of the ionic character.

Covalent compounds do not conduct electricity !hile ionic in the molten state/ do.

&ormu'a #a- (s) "g (s) *'- (s) i- (s) P012(s)

P03(')

(')

-(g)

C'-4(')

C'- (g)

5.

num,er

,1 ,$ ,3 ,' ,@

,3

,%

,'

,

,1

E.

conducti

ity in

mo'tenstate

hih very lo! none

tructure iant ionic iant

covalent

molecular covalent

*cid6,ase

character

basic amphotheric acidic

The acid#base properties of the o)ides depend on their bondin.

:etallic elements and thus ionic o)ides are basic. >on#metal o)ides !hich are covalent are

acidic. Those on the vere bet!een ionic and covalent are amphoteric. *mphotericsubstances sho! both acidic and basic properties such as !ater/.

>ote that5 *'7a'isare ,ases!hich are soluble in !ater. They form hydro)ide ions in a(ueous

solutions.


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Ch 13.1 Trends across Period 3

13. 1. 1. )plain the physical state $under standard conditions& and

electrical conducti#ity $in the molten state& of the chlorides and o)ides of

the elements in Period 3 in terms of their bonding and structure.

&ormu'ao8

ch'oride

#aC' (s) "gC'- (s)*'C' (s)

*'-C'3(g)iC'0(')

PC'9(s)

PC'(')-C'-(') C'-(g)

5.

num,er,1 ,$ ,3 ,'

,@

,3,1 &

E.

conducti

ity in

mo'ten

state

hih poor none

tructure iant ionic molecular covalent*cid6,ase

characterneutral

!ea*ly

acidicacidic

Because Cl is less electroneative than o)yen the transition from ionic to covalent occurs

earlier on in the period than for o)ides.

Al$Cl% is a dimer of AlCl3 !here the t!o bridin Cl atoms form dative covalent bonds formed

bet!een Al atoms.


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ydro'ysis o8 coa'ent ch'orides

Aluminium chloride

(aq )3+ (aq )+3Cl

Al Cl3(s ) Al

This !ill result in the formation of the

comple) ion AlH$/%D3,5

A comp'e5is !hen a central ion is surrounded by molecules or ions !hich posses a lone pair

of electrons. The liand has an independent e)istence as the surroundin species 'igands/

are bound via a dative covalent bond.

Comple)es are sho!n throuh the use of s(uare brac*ets.

The AlH$/%D3,

ion is acidic because the hih chare density of Al3,

attracts the electronsfrom the = H bond of the surroundin !ater molecules !hich results in the release of an H,

ion.

+(aq)2++H

Al (H2O )5 OH

3+ (aq )Al (H2O )6

etc.

Silicon and phosphorus chlorides

SiCl4

( l )+2H2

O ( l ) S i O2( s)+4HCl

PCl3(l )+3H

2O ( l ) H

3PO

3(aq )+3HCl (aq ) PCl

5(s )+4H

2O ( l ) H

3PO

4( aq )+5HCl ( aq )


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The enery separation of the t!o orbitals and thus the colour of the comple) depends on5

the nuclear chane

the chare density of the liand

the number of d electrons present the o)idation number of the central ion/

the shape of the comple) ion

13. 2. . 0tate e)amples of the catalytic action of transition elements and

their compounds.

! 13. 2. 4. 5utline the economic signi'cance of catalysts in the ,ontact and

6aber process.

There are t!o di0erent types of catalysts5

E$E;GE#TACT PMC"??

uses ;$@divanadium pento)ide/ as catalyst

2SO2(g)+O2(g)2SO3(g)

"GE#


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This vitamin is necessary in the production of erythrocytes and responsible for a

healthy nervous system.

ch 3 periodicity

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