IB Chemistry

Topic 3: Periodicity

Name ________________

2

Topic 3 and 13 – Periodicity

• Alkali metals: Group 1 elements. Strength of metallic bond gets weaker as atoms get larger. • Anion: A – charged ion. Decrease in size across a period as they are isoelectronic but have an increased

nuclear charge. Contain more e- than their parent atom, so they are larger in size. • Atomic radius: Half the distance between the nuclei of two bonded atoms of the same element.

Decreases across period as nuclear charge increases. Increases down a group because of greater number of energy levels.

• Catalyst: A substance that increases the rate of reaction while being recoverable in the end stage of the reaction, unchanged. Examples of catalytic transition metals: Fe is used in Haber process; V2O5 in Contact process; Ni in hydrogenation reactions; MnO2 with hydrogen peroxide.

• Cation: A + charged ion. Decrease in size across a period. Contain less e- than their parent atom, so they are smaller in size.

• Chloride: Chlorides of Na and Mg have an ionic structure, while all the remaining chlorides of period 3 elements have simple covalent structures. Still, Al2Cl6 can act as a poor conductor. NaCl dissolves in water to give a neutral solution, MgCl2 gives slightly acidic solution, while all other chlorides react vigorously with water to produce acidic solutions of HCl together with fumes of hydrogen chloride.

• Colored complex: A complex is a compound in which molecules or ions form dative bonds to a metal atom or ion. Colors are due to e- transitions between different d orbitals.

• Co-ordination number: Number of lone pairs bonded to the metal ion. Cl- often gives 4 coordinate bonds, CN- gives 6, H2O gives 6 and NH3 gives 4 or 6.

• D-d transition: The excitation of an e- from the lower of two energy level groups to the upper. As the ligand approaches the metal, the five d orbitals split. The difference in energy between the two levels corresponds to the wavelength of visible light, as incoming light causes energy of a particular wavelength to be absorbed by e- that are excited from the lower level to the higher. The amount that the d orbitals are split will determine the exact color.

• Degenerate: Of equal energy. In a free ion, the five d orbitals are degenerate. • Electronegativity: Relative measure of the attraction that an atom has for a shared pair of e- when it is

covalently bonded to another F is most→atom. Inversely proportional to size of atom electronegative.

• Group: Elements with the same number of valence e-. • Halide ions: Ions of the halogens. Their presence can be detected by the addition of silver nitrate. AgCl

is white, AgBr is cream-colored, and AgI is yellow. Silver halides react with light to form silver metal. • Isoelectronic: Containing the same number of e-. • Ligand: A molecule or ion that can donate e-. • Melting point: Depends on both the structure of element and type of attractive forces holding the atoms

together. Increases across the period while following elements which exhibit metallic bonding (due to increased strength following increased number of valence e-.) Highest m.p. of period lies with macromolecular covalent structure (with very strong bonds). Sharp decrease in m.p. with elements that exhibit simple molecular structures with only van der Waals’ forces between them. Lowest m.p. with noble gases, which are monatomic. Down Group 1, m.p. decreases as atoms get larger and strength of metallic bond get weaker. →Down Group 7, van der Waals’ forces increase as molar mass increases m.p. increases.

• Metalloid: An element that possesses some of the properties of a metal and some of a non-metal. While metal oxides tend to be basic and non-metal oxides tend to be acidic, metalloid oxides such as aluminium oxide can be amphoteric.

3

• Oxide: Metal oxides are ionic (explains conductivity, m.p. and b.p.) and react with water to form alkaline solutions. SiO2 is covalent macromolecular, and the remaining oxides are simple covalent. Oxides of period 3 elements are solid from Na2O to P4O10 and P4O6, while SO3 and C. Al2O3 and SiO2 do°Cl2O7 are liquid and SO2 and Cl2O are gases at 25 not react with water, but Al2O3 can act amphoterically depending on whether it is reacted with a base or an acid. Remaining oxides are acidic.

• Period: Elements with the same outer shell of valence e-. • Periodicity: The repeating pattern of physical and chemical properties as shown by the different periods. • Structure, giant covalent: Very hard but brittle. Very high m.p. and b.p. Do not conduct in any state.

Insoluble. • Structure, giant ionic: Hard but brittle. High m.p. and b.p. Conduct when molten or aqueous, but not as

solids. • Structure, giant metallic: Malleable, not brittle. M.p. and b.p. dependent on no. of valence e-. Good

conductivity. • Structure, molecular covalent: Usually soft and malleable unless hydrogen bonded. Low m.p. and b.p.

Do not conduct in any state. Often soluble in non-aqueous solvents, unless they can hydrogen bond to water.

• Transition element: An element that possesses an incomplete d sub-level in one or more of its oxidation states. Often very efficient catalysts as they can exist in a variety of oxidation states (all except Ti have oxidation state of +2). Form colored complexes.

Topic 3: Periodicity

Chemistry guide42

Esse

ntia

l ide

a:Th

e ar

rang

emen

t of e

lem

ents

in th

e pe

riodi

c ta

ble

help

s to

pre

dict

thei

r ele

ctro

n co

nfig

urat

ion.

3.1

Perio

dic

tabl

e

Nat

ure

of s

cien

ce:

Obt

ain

evid

ence

for s

cien

tific

theo

ries

by m

akin

g an

d te

stin

g pr

edic

tions

bas

ed o

n th

em—

scie

ntis

ts o

rgan

ize

subj

ects

bas

ed o

n st

ruct

ure

and

func

tion;

the

perio

dic

tabl

e is

a

key

exam

ple

of th

is. E

arly

mod

els

of th

e pe

riodi

c ta

ble

from

Men

dele

ev, a

nd la

ter M

osel

ey,a

llow

ed fo

r the

pre

dict

ion

of p

rope

rties

of e

lem

ents

that

had

not

yet

bee

n di

scov

ered

. (1.

9)

Und

erst

andi

ngs:

�Th

e pe

riodi

c ta

ble

is a

rrang

ed in

to fo

ur b

lock

s as

soci

ated

with

the

four

sub

-le

vels

—s,

p, d

, and

f.

�Th

e pe

riodi

c ta

ble

cons

ists

of g

roup

s (v

ertic

al c

olum

ns) a

nd p

erio

ds (h

oriz

onta

l ro

ws)

.

�Th

e pe

riod

num

ber (n)

is th

e ou

ter e

nerg

y le

vel t

hat i

s oc

cupi

ed b

y el

ectro

ns.

�Th

e nu

mbe

r of t

he p

rinci

pal e

nerg

y le

vel a

nd th

e nu

mbe

r of t

he v

alen

ce

elec

trons

in a

n at

om c

an b

e de

duce

d fro

m it

s po

sitio

n on

the

perio

dic

tabl

e.

�Th

e pe

riodi

c ta

ble

show

s th

e po

sitio

ns o

f met

als,

non

-met

als

and

met

allo

ids.

App

licat

ions

and

ski

lls:

�D

educ

tion

of th

e el

ectro

n co

nfig

urat

ion

of a

n at

om fr

om th

e el

emen

t’s p

ositi

on

on th

e pe

riodi

c ta

ble,

and

vic

e ve

rsa.

Gui

danc

e:

�Th

e te

rms

alka

li m

etal

s, h

alog

ens,

nob

le g

ases

, tra

nsiti

on m

etal

s, la

ntha

noid

san

d ac

tinoi

ds s

houl

d be

kno

wn.

�Th

e gr

oup

num

berin

g sc

hem

e fro

m g

roup

1 to

gro

up 1

8, a

s re

com

men

ded

by

IUP

AC

, sho

uld

be u

sed.

Inte

rnat

iona

l-min

dedn

ess:

�Th

e de

velo

pmen

t of t

he p

erio

dic

tabl

e to

ok m

any

year

s an

d in

volv

ed s

cien

tists

fro

m d

iffer

ent c

ount

ries

build

ing

upon

the

foun

datio

ns o

f eac

h ot

her’s

wor

k an

d id

eas.

Theo

ry o

f kno

wle

dge:

�W

hat r

ole

did

indu

ctiv

e an

d de

duct

ive

reas

onin

g pl

ay in

the

deve

lopm

ent o

f the

pe

riodi

c ta

ble?

Wha

t rol

e do

es in

duct

ive

and

dedu

ctiv

e re

ason

ing

have

in

scie

nce

in g

ener

al?

Util

izat

ion:

�O

ther

sci

entif

ic s

ubje

cts

also

use

the

perio

dic

tabl

e to

und

erst

and

the

stru

ctur

e an

d re

activ

ity o

f ele

men

ts a

s it

appl

ies

to th

eir o

wn

disc

iplin

es.

Syl

labu

s an

d cr

oss-

curri

cula

r lin

ks:

Topi

c 2.

2—el

ectro

n co

nfig

urat

ion

Aim

s:

�A

im 3

: App

ly th

e or

gani

zatio

n of

the

perio

dic

tabl

e to

und

erst

and

gene

ral

trend

s in

pro

perti

es.

�A

im 4

:Be

able

to a

naly

seda

ta to

exp

lain

the

orga

niza

tion

of th

e el

emen

ts.

�A

im 6

: Be

able

to re

cogn

ize

phys

ical

sam

ples

or i

mag

es o

f com

mon

ele

men

ts.

Topi

c 3:

Per

iodi

city

6

hour

s

Core

Topic 3: Periodicity

Chemistry guide 43

Esse

ntia

l ide

a:E

lem

ents

sho

w tr

ends

in th

eir p

hysi

cal a

nd c

hem

ical

pro

perti

es a

cros

s pe

riods

and

dow

n gr

oups

.

3.2

Perio

dic

tren

ds

Nat

ure

of s

cien

ce:

Look

ing

for p

atte

rns—

the

posi

tion

of a

n el

emen

t in

the

perio

dic

tabl

e al

low

s sc

ient

ists

to m

ake

accu

rate

pre

dict

ions

of i

ts p

hysi

cal a

nd c

hem

ical

pro

perti

es. T

his

give

s sc

ient

ists

the

abili

ty to

syn

thes

ize

new

sub

stan

ces

base

d on

the

expe

cted

reac

tivity

of e

lem

ents

. (3.

1)

Und

erst

andi

ngs:

�V

ertic

al a

nd h

oriz

onta

l tre

nds

in th

e pe

riodi

c ta

ble

exis

t for

ato

mic

radi

us, i

onic

ra

dius

, ion

izat

ion

ener

gy, e

lect

ron

affin

ity a

nd e

lect

rone

gativ

ity.

�Tr

ends

in m

etal

lic a

nd n

on-m

etal

lic b

ehav

iour

are

due

to th

e tre

nds

abov

e.

�O

xide

s ch

ange

from

bas

ic th

roug

h am

phot

eric

to a

cidi

c ac

ross

a p

erio

d.

App

licat

ions

and

ski

lls:

�P

redi

ctio

n an

d ex

plan

atio

n of

the

met

allic

and

non

-met

allic

beh

avio

ur o

f an

elem

ent b

ased

on

its p

ositi

on in

the

perio

dic

tabl

e.

�D

iscu

ssio

n of

the

sim

ilarit

ies

and

diffe

renc

es in

the

prop

ertie

s of

ele

men

ts in

th

e sa

me

grou

p, w

ith re

fere

nce

to a

lkal

i met

als

(gro

up 1

) and

hal

ogen

s (g

roup

17

).

�C

onst

ruct

ion

of e

quat

ions

to e

xpla

in th

e pH

cha

nges

for r

eact

ions

of N

a 2O

, M

gO, P

4O10

, and

the

oxid

es o

f nitr

ogen

and

sul

fur w

ith w

ater

.

Gui

danc

e:

�O

nly

exam

ples

of g

ener

al tr

ends

acr

oss

perio

ds a

nd d

own

grou

ps a

re re

quire

d.

For i

oniz

atio

n en

ergy

the

disc

ontin

uitie

s in

the

incr

ease

acr

oss

a pe

riod

shou

ld

be c

over

ed.

�G

roup

tren

ds s

houl

d in

clud

e th

e tre

atm

ent o

f the

reac

tions

ofa

lkal

i met

als

with

w

ater

, alk

ali m

etal

s w

ith h

alog

ens

and

halo

gens

with

hal

ide

ions

.

Inte

rnat

iona

l-min

dedn

ess:

�In

dust

rializ

atio

n ha

s le

d to

the

prod

uctio

n of

man

y pr

oduc

ts th

at c

ause

glo

bal

prob

lem

s w

hen

rele

ased

into

the

envi

ronm

ent.

Theo

ry o

f kno

wle

dge:

�Th

e pr

edic

tive

pow

er o

f Men

dele

ev’s

Per

iodi

c Ta

ble

illus

trate

s th

e “ri

sk-ta

king

” na

ture

of s

cien

ce. W

hat i

s th

e de

mar

catio

n be

twee

n sc

ient

ific

and

pseu

dosc

ient

ific

clai

ms?

�Th

e P

erio

dic

Tabl

e is

an

exce

llent

exa

mpl

e of

cla

ssifi

catio

n in

sci

ence

. How

do

es c

lass

ifica

tion

and

cate

goriz

atio

n he

lp a

nd h

inde

r the

pur

suit

of

know

ledg

e?

Util

izat

ion:

Syl

labu

s an

d cr

oss-

curri

cula

r lin

ks:

Topi

c 2.

2—an

omal

ies

in fi

rst i

oniz

atio

n en

ergy

val

ues

can

be c

onne

cted

to s

tabi

lity

in e

lect

ron

conf

igur

atio

n To

pic

8.5—

prod

uctio

n of

aci

d ra

in

Aim

s:

�A

ims

1 an

d8:

Wha

t is

the

glob

al im

pact

of a

cid

depo

sitio

n?

�A

im 6

:Exp

erim

ent w

ith c

hem

ical

tren

ds d

irect

ly in

the

labo

rato

ry o

r thr

ough

the

use

of te

ache

r dem

onst

ratio

ns.

�A

im 6

: The

use

of t

rans

ition

met

al io

ns a

s ca

taly

sts

coul

d be

inve

stig

ated

.

�A

im 7

:Per

iodi

c tre

nds

can

be s

tudi

ed w

ith th

e us

e of

com

pute

r dat

abas

es.

Topic 13: The periodic table—the transition metals

Chemistry guide78

Esse

ntia

l ide

a:Th

e tra

nsiti

on e

lem

ents

hav

e ch

arac

teris

tic p

rope

rties

; the

se p

rope

rties

are

rela

ted

to th

eir a

ll ha

ving

inco

mpl

ete

d su

blev

els.

13.1

Firs

t-row

d-b

lock

ele

men

ts

Nat

ure

of s

cien

ce:

Look

ing

for t

rend

s an

d di

scre

panc

ies—

trans

ition

ele

men

ts fo

llow

cer

tain

pat

tern

s of

beh

avio

ur. T

he e

lem

ents

Zn,

Cr a

nd C

u do

not

follo

w th

ese

patte

rns

and

are

ther

efor

e co

nsid

ered

ano

mal

ous

in th

e fir

st-ro

w d

-blo

ck. (

3.1)

Und

erst

andi

ngs:

�Tr

ansi

tion

elem

ents

hav

e va

riabl

e ox

idat

ion

stat

es, f

orm

com

plex

ions

with

lig

ands

, hav

e co

lour

ed c

ompo

unds

, and

dis

play

cat

alyt

ic a

nd m

agne

tic

prop

ertie

s.

�Zn

isno

t con

side

red

to b

e a

trans

ition

ele

men

t as

itdo

esno

t for

m io

nsw

ith

inco

mpl

ete

d-or

bita

ls.

�Tr

ansi

tion

elem

ents

sho

w a

n ox

idat

ion

stat

eof

+2

whe

n th

e s-

elec

trons

are

re

mov

ed.

App

licat

ions

and

ski

lls:

�E

xpla

natio

n of

the

abili

ty o

f tra

nsiti

on m

etal

s to

form

var

iabl

e ox

idat

ion

stat

es

from

suc

cess

ive

ioni

zatio

n en

ergi

es.

�E

xpla

natio

n of

the

natu

re o

f the

coor

dina

tebo

nd w

ithin

a c

ompl

ex io

n.

�D

educ

tion

of th

e to

tal c

harg

e gi

ven

the

form

ula

of th

e io

n an

d lig

ands

pre

sent

.

�E

xpla

natio

nof

the

mag

netic

pro

perti

es in

tran

sitio

n m

etal

s in

term

s of

unp

aire

d el

ectro

ns.

Gui

danc

e:

�C

omm

on o

xida

tion

num

bers

of t

he tr

ansi

tion

met

al io

ns a

re li

sted

in th

e da

tabo

okle

t in

sect

ions

9 a

nd 1

4.

Inte

rnat

iona

l-min

dedn

ess:

�Th

e pr

oper

ties

and

uses

of t

he tr

ansi

tion

met

als

mak

e th

em im

porta

nt

inte

rnat

iona

l com

mod

ities

. Min

ing

for p

reci

ous

met

als

is a

maj

or fa

ctor

in th

e ec

onom

ies

of s

ome

coun

tries

.

Theo

ry o

f kno

wle

dge:

�Th

e m

edic

al s

ymbo

ls fo

r fem

ale

and

mal

e or

igin

ate

from

the

alch

emic

al

sym

bols

for c

oppe

r and

iron

. Wha

t rol

e ha

s th

e ps

eudo

scie

nce

of a

lche

my

play

ed in

the

deve

lopm

ent o

f mod

ern

scie

nce?

Util

izat

ion:

Syl

labu

s an

d cr

oss-

curri

cula

r lin

ks:

Topi

c 9.

1—re

dox

reac

tions

Topi

c 10

.2—

oxid

atio

n of

alc

ohol

s, h

ydro

gena

tion

of a

lken

esO

ptio

n A

.3—

hom

ogen

eous

and

het

erog

eneo

us c

atal

ysis

Aim

s:

�A

im 6

: The

oxi

datio

n st

ates

of v

anad

ium

and

man

gane

se, f

or e

xam

ple,

cou

ld b

e in

vest

igat

ed e

xper

imen

tally

. Tra

nsiti

on m

etal

s co

uld

bean

alys

ed u

sing

redo

x tit

ratio

ns.

�A

im 8

: Eco

nom

ic im

pact

of t

he c

orro

sion

of i

ron.

Topi

c 13

: The

per

iodi

c ta

ble—

the

tran

sitio

n m

etal

s 4

hour

s

Addi

tiona

l hig

her l

evel

Topic 13: The periodic table—the transition metals

Chemistry guide 79

Esse

ntia

l ide

a:d-

orbi

tals

hav

e th

e sa

me

ener

gy in

an

isol

ated

ato

m, b

ut s

plit

into

two

sub-

leve

ls in

a c

ompl

ex io

n. T

he e

lect

ric fi

eld

of li

gand

s m

ay c

ause

the

d-or

bita

ls in

co

mpl

ex io

ns to

spl

it so

that

the

ener

gy o

f an

elec

tron

trans

ition

bet

wee

n th

em c

orre

spon

ds to

a p

hoto

n of

vis

ible

ligh

t.

13.2

Col

oure

d co

mpl

exes

Nat

ure

of s

cien

ce:

Mod

els

and

theo

ries—

the

colo

ur o

f tra

nsiti

on m

etal

com

plex

es c

an b

e ex

plai

ned

thro

ugh

the

use

of m

odel

s an

d th

eorie

s ba

sed

on h

ow e

lect

rons

are

dis

tribu

ted

in d

-orb

itals

. (1

.10)

Tran

sdis

cipl

inar

y—co

lour

link

ed to

sym

met

ry c

an b

e ex

plor

ed in

the

scie

nces

, arc

hite

ctur

e, a

nd th

e ar

ts. (

4.1)

Und

erst

andi

ngs:

�Th

e d

sub-

leve

l spl

its in

to tw

o se

ts o

f orb

itals

of d

iffer

ent e

nerg

y in

a c

ompl

ex

ion.

�C

ompl

exes

of d

-blo

ck e

lem

ents

are

col

oure

d, a

s lig

ht is

abs

orbe

d w

hen

an

elec

tron

is e

xcite

d be

twee

n th

e d-

orbi

tals

.

�Th

e co

lour

abs

orbe

d is

com

plem

enta

ry to

the

colo

ur o

bser

ved.

App

licat

ions

and

ski

lls:

�E

xpla

natio

n of

the

effe

ct o

f the

iden

tity

of th

e m

etal

ion,

the

oxid

atio

n nu

mbe

r of

the

met

al a

nd th

e id

entit

y of

the

ligan

d on

the

colo

ur o

f tra

nsiti

on m

etal

ion

com

plex

es.

�E

xpla

natio

n of

the

effe

ct o

f diff

eren

t lig

ands

on

the

split

ting

of th

e d-

orbi

tals

in

trans

ition

met

al c

ompl

exes

and

col

our o

bser

ved

usin

g th

e sp

ectro

chem

ical

se

ries.

Gui

danc

e:

�Th

e sp

ectro

chem

ical

ser

ies

is g

iven

in th

e da

ta b

ookl

et in

sec

tion

15. A

list

of

poly

dent

ate

ligan

ds is

giv

en in

the

data

boo

klet

in s

ectio

n 16

.

�S

tude

nts

are

not e

xpec

ted

to re

call

the

colo

ur o

f spe

cific

com

plex

ions

.

Util

izat

ion:

Syl

labu

s an

d cr

oss-

curri

cula

r lin

ks:

Topi

c 2.

2—el

ectro

n co

nfig

urat

ion

of a

tom

s an

d io

ns

Aim

s:

�A

im 6

: The

col

ours

of a

rang

e of

com

plex

ions

, of e

lem

ents

suc

h as

Cr,

Fe, C

o,

Ni a

nd C

u co

uld

be in

vest

igat

ed.

�A

im 7

: Com

plex

ions

cou

ld b

e in

vest

igat

ed u

sing

a s

pect

rom

eter

dat

a lo

gger

.

�A

im 8

: The

con

cent

ratio

n of

toxi

c tra

nsiti

on m

etal

ions

nee

ds to

be

care

fully

m

onito

red

in e

nviro

nmen

tal s

yste

ms.

Topic 13: The periodic table—the transition metals

Chemistry guide80

13.2

Col

oure

d co

mpl

exes

�Th

e re

latio

n be

twee

n th

e co

lour

obs

erve

d an

d ab

sorb

ed is

illu

stra

ted

by th

e co

lour

whe

el in

the

data

boo

klet

in s

ectio

n 17

.

�S

tude

nts

are

not e

xpec

ted

to k

now

the

diffe

rent

spl

ittin

g pa

ttern

s an

d th

eir

rela

tion

to th

e co

ordi

natio

n nu

mbe

r. O

nly

the

split

ting

of th

e 3-

dor

bita

ls in

an

octa

hedr

al c

ryst

al fi

eld

is re

quire

d.

4

The End