Periodic Table of elements – divided to Groups, Periods and Blocks

Group 1 18

Groups – Vertical column • Same number of valence electron • Same number outmost electrons

Block – different region in periodic table • s, p, d, f blocks • s block- elements with valence e in s sublevel • p block – elements with valence e in p sublevel

Period- Horizontal row • 7 periods/row • Same number of shell

Periods 1 7

s block - s orbitals partially fill

d block • d orbitals partially fill

f block • f orbital partially fill

p block • p orbital partially fill

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Periodic Table – s, p d, f blocks elements s block elements • s orbitals partially fill

p block elements • p orbital partially fill

d block elements • d orbitals partially fill • transition elements

1 H 1s1

2 He 1s2

11 Na [Ne] 3s1

12 Mg [Ne] 3s2

5 B [He] 2s2 2p1

6 C [He] 2s2 2p2

7 N [He] 2s2 2p3

8 O [He] 2s2 2p4

9 F [He] 2s2 2p5

10 Ne [He] 2s2 2p6

13 Al [Ne] 3s2 3p1

14 Si [Ne] 3s2 3p2

15 P [Ne] 3s2 3p3

16 S [Ne] 3s2 3p4

17 CI [Ne] 3s2 3p5

18 Ar [Ne] 3s2 3p6

19 K [Ar] 4s1

20 Ca [Ar] 4s2

21 Sc [Ar] 4s2 3d1

22 Ti [Ar] 4s2 3d2

23 V [Ar] 4s2 3d13

24 Cr [Ar] 4s1 3d5

25 Mn [Ar] 4s2 3d5

26 Fe [Ar] 4s2 3d6

27 Co [Ar] 4s2 3d7

28 Ni [Ar] 4s2 3d8

29 Cu [Ar] 4s1 3d10

30 Zn [Ar] 4s2 3d10

n = 2 period 2

3 Li [He] 2s1

4 Be [He] 2s2

Click here video s,p,d,f blocks, Click here video on s,p,d,f notation Click here electron structure

Video on electron configuration

f block elements • f orbitals partially fill

Periodicity

Predicted pattern/trends in physical/chemical properties across period.

Physical properties Chemical properties

Physical change - without change in molecular composition. – appearance change - composition remain unchanged.

Chemical change – diff composition from original substances - chemical bonds broken/ formed - new products formed

Element properties Atomic properties

• Color, texture, odor • Density, hardness, ductility • Brittleness, Malleability • Melting /boiling point • Solubility, polarity

• Ionization energy • Atomic radii • Ionic radii • Electronegativity

Periodic Trends • Across period 2/3 • Down group 1/17

Gp 1 Gp 17

period 3

period 2

Ionization energy

Atomic/ionic radii

Melting point

Electronegativity

Factors affecting ionization energy

Distance from nucleus Nuclear charge

Ionization energy (IE)

2nd Ionization energy Min energy to remove 1 mole e from 1 mole of +1 ion to form +2 ion M+(g) M2+ (g) + e

1st Ionization energy Min energy to remove 1 mole e from 1 mole of element in gaseous state M(g) M+ (g) + e

Ionization energy

Distance near to nucleus – IE High Distance far away nucleus – IE Low

Nuclear charge high (more proton) – IE High Nuclear charge low (less proton) – IE Low

electron

Effective Nuclear Charge (ENC)/(Zeff) • Screening effect/shielding • Effective nuclear charge (ENC)/(Zeff) (Zeff) = Nuclear charge (Z) – shielding effect • Net positive charge felt by valence electrons.

Why IE increases across the period? Why IE decreases down a group ?

1 2 3

Higher electron/electron repulsion

Easier valence e to leave

IE – Low

Inner electron – shield valence e from positive nuclear charge

Strong electrostatic forces attraction bet nucleus and e

IE – High

Distance near Nuclear charge

Strong electrostatic forces attraction bet nucleus and e

IE – High

+3 +4 +5 +6

Nuclear charge increase

+6

Why IE increases across the period 2? IE drop from Be to B and N to O

IE increases across period 2

Nuclear charge increase

Strong electrostatic forces attraction bet nucleus and e

IE – High

1s

2p

2s

1s2 2s1 1s2 2s2 1s2 2s2 2p1 1s2 2s2 2p2 1s2 2s2 2p3 1s2 2s2 2p4 1s2 2s2 2p5 1s2 2s2 2p6

Li Be B C N O F Ne

period 2

IE drop from Be to B IE drop from N to O

Electron in p sublevel of B – further away from nucleus

Weak electrostatic force attraction between nucleus and electron

IE - Low

2 electrons in same p orbital - Greater e/e repulsion

Easier to remove e

IE - Low

Ionization Energy- Period 2

Why IE increases across the period 3? IE drop from Mg to AI and P to S

IE increases across period 3

Nuclear charge increase

Strong electrostatic forces attraction bet nucleus and e

IE – High

3s

3p

[Ne] 3s1 [Ne] 3s2 [Ne] 3s2 3p1

Na Mg AI Si P S CI Ar

Period 3

IE drop from Mg to AI IE drop from P to S

Electron in p sublevel of AI – further away from nucleus

Weak electrostatic force attraction between nucleus and electron

IE - Low

2 electrons in same p orbital - Greater e/e repulsion

Easier to remove e

IE - Low

Ionization Energy- Period 3

[Ne] 3s2 3p2 [Ne] 3s2 3p3 [Ne] 3s2 3p4 [Ne] 3s2 3p5 [Ne] 3s2 3p6

Period 3 – 3 shells/energy level

Valence e further from nucleus

Weaker electrostatic forces attraction bet nucleus and e

IE – Lower

1s

2p

2s

1s2 2s1 1s2 2s2 1s2 2s2 2p1 1s2 2s2 2p2 1s2 2s2 2p3 1s2 2s2 2p4 1s2 2s2 2p5 1s2 2s2 2p6

Li Be B C N O F Ne

Ionization Energy- Period 2 and 3 Why IE period 3 lower than 2? IE for Period 2 and 3

period 2

Na

1s

2s

2p

3s

3p

[Ne] 3s1

Mg AI Si P S CI Ar

Period 3

[Ne] 3s2 3p1 [Ne] 3s2 [Ne] 3s2 3p2 [Ne] 3s2 3p3 [Ne] 3s2 3p4 [Ne] 3s2 3p5 [Ne] 3s2 3p6

High shielding effect – more inner e Period 3

3rd level

Full electron configuration, 2.8/2.8.8

Most energetically stable structure

Difficult to lose electron

IE – High

1s

2p

2s

1s2 2s1 1s2 2s2 1s2 2s2 2p1 1s2 2s2 2p2 1s2 2s2 2p3 1s2 2s2 2p4 1s2 2s2 2p5 1s2 2s2 2p6

Li Be B C N O F Ne

Ionization Energy- Period 2 and 3 Why Ne and Ar have HIGH IE ? IE for Ne and Ar

period 2

Na

1s

2s

2p

3s

3p

[Ne] 3s1

Mg AI Si P S CI Ar

Period 3

[Ne] 3s2 3p1 [Ne] 3s2 [Ne] 3s2 3p2 [Ne] 3s2 3p3 [Ne] 3s2 3p4 [Ne] 3s2 3p5 [Ne] 3s2 3p6

neon

argon

Atomic Radius

How to measure atomic radius?

Atom not like a ball – can’t measure its radius directly Uncertain about position of electron – uncertain of atomic radius

✗

✔

Distance between nucleus and outmost electrons. Atomic radius

Uncertain abt electron position

Depend on type of bonding – covalent or metallic

Half the distance bet nuclei of two closest identical atoms.

Atomic Radius

Covalent Molecule Noble gas Monoatomic atoms

Metallic elements Ionic compounds

½ bond length

Covalent Radius

½ bond length of 2 atom

½ bond length

Van Der Waals radius

½ bond length of nuclei atoms not bonded together (noble gas)

½ bond length bet nuclei of neighbouring metal ions

Ionic radius

Measure indirectly using internucleus distance

Metallic radius

½ bond length

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Click here video calculating radius Li

Effective nuclear charge

Click here video ENC Li

Effective Nuclear Charge (ENC)/(Zeff) • Screening effect/shielding • Effective nuclear charge (ENC)/(Zeff) (Zeff) = Nuclear charge (Z) – shielding effect • Net positive charge felt by valence electrons.

Effective nuclear charge magnesium (2.8.2)

10 inner electron shield 12+ protons

Calculate Z(eff) for Li

Effective nuclear charge, (Zeff) = +2

Valence electron feel a net (12-10 = +2)

net +2

Z(eff) = +1.26 NOT +1 (calculation shown above)

1st IE Li = 521kJ/mol

2

2

21312521

Z

26.1effZ

2 inner electron shield 3+ protons

Valence electron felt a net (3-2) = +1

Calculate atomic radius Li using Z(eff)

Formula ionization energy coulomblcentripeta FF

2

2

R

kqZ

r

mv

mv

h

p

h

Rm

hv

R

R

n

22

2

R

kqZ

Rm

mh

222

2

kqZm

hR

2

2

m

hv

2nd energy level n=2

pmR 168

2nd energy level n = 2

m = mass electron -9.1 x 10-31

h = plank constant – 6.626 x 10-34

k = coulomb constant – 9.0 x 109

q = charge electron – 1.6 x 10-19

Z = effective nuclear charge - +1.26

R

1 2

Lithium (2.1)

Calculate Z(eff) and atomic radius for Li

2

2

1312n

ZIE

Effective Nuclear charge increase

Why atomic radius decrease across period 2/3 Atomic Radius (Covalent radius)

Atomic radius decrease across period 2/3

Effective Nuclear charge increase

Strong electrostatic forces attraction bet nucleus and e

Size decrease

Li

period 2

Atomic Radius- Period 2/3

Be

+4 B

+5 C

+6 N

+7 +3 O

+8

F

+9

Effective Nuclear charge increase

period 3

Na

+11

Mg

+12

AI

+13 Si

+14 P

+15 S

+16

CI

+17

Gp 17

Number shell increase

Valence e further away from nucleus

Atomic radius High

Why atomic radius increase down Gp 17?

Screening/shielding effect increase

Inner shell electrons electron electron repulsion increase

Ionic radii

2.8.8 2.8.8 - 2 shells

2.8.6 2.8.7 - 3 shells

2.8 2.8 2.8 - 2 shells

2.8.1 2.8.2 2.8.3 - 3 shells

Atomic and Ionic Radius- Period 2/3 Positive Ions (+) Negative Ions (-)

Ionic radii Positive ion (+) smaller

Comparison bet atomic/ionic radii

Decrease in number of shells – loss of electron

Less electron electron repulsion

Size decrease

Atomic radii

Ionic radii

Ionic radii Negative ion (-) bigger

Increase in number of shells – gain of electron

Increase electron electron repulsion

Size increase

Comparison bet atomic/ionic radii

Atomic radii

Ionic radii

Na

Na+

Mg

Mg2+

AI

AI3+

Atomic radii

Ionic radii

AI S CI

S2- CI-

Atomic radii

Period 2

Shared electron cloud closer to O

Electronegativity

Electronegativity (EN) • Tendency of atom to attract/pull shared/bonding electron to itself • EN value higher – pull/attract electron higher (EN value from 0.7 – 4)

EN highest EN lowest

Factors affecting EN value • Size of atom/distance – small size/distance – stronger attraction for electron • Nuclear charge – higher nuclear charge – stronger attraction for electron

Electronegativity • EN increase up a Group • EN increase across a Period

F

CI

Br

I

Size increase

Attraction electron decrease

EN lower

Size

Be

+4

Li

+3 B

+5 N

+7

O

+8 F

+9

EN increase across period 2

Nuclear charge

EN increase across period 2 Nuclear charge increase Strong attraction for electron

EN increase

Gp 17

C

+6

EN decrease down gp 17

Melting Point • Temp when solid turn to liquid (temp remain constant) • Energy absorb to overcome forces attraction bet molecule

Factors affecting melting point

• Melting point across Period 2/3 • Melting point down Gp 1/17

Gp 1 Gp 17

Period 2/3

Structure

Metallic/Non Metallic structure

Covalent structure

Giant molecular structure

Type of bonding/forces

Ionic Bonding Covalent Bonding Ionic structure

Simple molecular structure

Metallic Bonding

Melting Point

period 2

period 3

Li

Be

B

C

N O F Ne

Na

Mg AI

Si

P S CI

Melting point across Period 2 and 3

Melting Point Melting point across Period 2

period 2

Van der waals forces bet molecules

Across period 2 • m/p increase from Li – C • m/p drop from N – Ne • Metallic – non metallic

Li Be B C N O F Ne

m/p (/C)

180 1280 2300 3730 -210 -218 -220 -249

structure metallic metallic Giant covalent

Giant covalent

Simple molecular

Simple molecular

Simple molecular

Mono atomic

bonding metallic metallic Giant covalent

Giant covalent

Simple covalent

Simple covalent

Simple covalent

Simple covalent

Li

Be

B

C

N O F Ne

Metallic bonding Giant covalent Simple covalent

Strong attraction bet nucleus with sea of electrons

Macromolecular structure with strong covalent bonds

Simple molecular weak Van Der Waals forces attraction bet molecules

Melting point for metallic/non metallic

High m/p Highest m/p Low m/p

Melting Point Melting point across Period 3

Period 3

Van der waals forces between molecules

Across period 3 • m/p increase from Na – Si • m/p drop from P – Ar • Metallic – non metallic

Na Mg AI Si P S CI Ar

m/p (/C)

98 650 660 1423 44 120 -101 -189

structure metallic metallic metallic Giant covalent

Simple molecular

Simple molecular

Simple molecular

Mono atomic

bonding metallic metallic metallic Giant covalent

Simple covalent

Simple covalent

Simple covalent

Simple covalent

Na

Mg AI

Si

CI Ar

Metallic bonding Giant covalent Simple covalent

Strong attraction bet nucleus with sea of electrons

Macromolecular structure with strong covalent bonds

Simple molecular weak Van Der Waals forces attraction bet molecules

Melting point for metallic/non metallic

High m/p

P S

Highest m/p Low m/p

Valence e further away from nucleus Weak forces attraction bet nucleus and e

Number shell/energy level increase

Melting point – Group 1 and 17

IE decrease down group

IE – Low

Atomic Radius

Gp 1

Na

Li

K

Rb

Gp 17

F

CI

Br

I

2.1

2.8.1

2.8.8.1

2.8.8.18.1

shell shell

2.7

2.8.7

2.8.18.7

2.8.18.18.7

Atomic Radius

Atomic Radius- Group 1 and 17 Ionization Energy – Group 1 and 17

Why atomic radius increase ?

Number shell increase

Valence e further away from nucleus

Atomic radius High

Gp 17 Gp 1

Li

Na

K

Rb

F

CI

Br

I

Melting point Ionization Energy

Atomic Radius Atomic Radius

Rb

K

Na

Li

I

Br

CI

F

Gp 1 Gp 17

m/p down Gp 1 m/p increase Gp 17

Metallic bonding Melting point

Attraction bet nucleus and sea electrons decrease

Size increase Size increase VDF increase

IMF attraction bet molecules increase

Melting point