PERIODICITY (TOPICS 3 AND 13)

IB Chemistry HL2

Review: Periodic table, Physical and Chemical Properties of elements (Topic

3) Describe the arrangement of elements in the periodic table in order of

increasing atomic number (5.2.12.A.3) Distinguish between the terms group and period (5.2.12.A.3) Apply the relationship between the electron arrangement of elements and

their position in the periodic table up to element n=20 (5.2.12.A.3) Apply the relationship between the number of electrons in the highest

occupied energy level for an element and its position on the periodic table (5.2.12.A.3)

Define the terms first ionization energy and electronegativity. Describe and explain the trends in atomic radii, ionic radii, first ionization

energy, electronegativity, and melting points for alkali metals and the halogens.

Describe and explain the trends in atomic radii, ionic radii, first ionization energies, and electronegativity for elements across period 3 (5.2.12.A.3)

Compare the relative electronegativity of two or more elements based on their positions in the periodic table.

Discuss the similarities and differences in the chemical properties of elements in the same group

Discuss the changes in nature, from ionic to covalent and from basic to acidic, of the oxides across Period 3.

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http://www.youtube.com/watch?v=OduTDUGeAXE&feature=player_detailpage

IB note: Inner transition elements are of little interest at this level

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Trends in Atomic Radii

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Comparison of Atomic Radii with Ionic Radii

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Cation is always smaller than atom from which it is formed.Anion is always larger than atom from which it is formed.

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Ionization energy is the minimum energy (kJ/mol) required to remove an electron from a gaseous atom in its ground state.

I1 + X (g) X+

(g) + e-

I2 + X+(g) X2+

(g) + e-

I3 + X2+(g) X3+

(g) + e-

I1 first ionization energy

I2 second ionization energy

I3 third ionization energy

I1 < I2 < I3

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General Trends in First Ionization Energies

Increasing First Ionization Energy

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Electron affinity is the negative of the energy change that occurs when an electron is accepted by an atom in the gaseous state to form an anion.

X (g) + e- X-(g)

F (g) + e- F-(g)

O (g) + e- O-(g)

H = -328 kJ/mol EA = +328 kJ/mol

H = -141 kJ/mol EA = +141 kJ/mol

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The metals in these two groups have similar outer electron configurations, with one electron in the outermost s orbital.Chemical properties are quite different due to difference in the ionization energy.

Comparison of Group 1A and 1B

Lower I1, more reactive

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Properties of Oxides Across a Period

basic acidic

Do NOW

Classify the following oxides as acidic, basic, or amphoteric:

(a)Na2O

(b)P4O10

(c)SO2

Objectives (Topic 13)Trends Across Period 3 13.1.1 Explain the physical states (under standard conditions)

and electrical conductivity (in the molten state) of the chlorides and oxides of the elements in period 3 in terms of their bonding and structure.

http://www.youtube.com/watch?v=IHNEe01Dy8Q 13.1.2 Describe the reactions of chlorine and the chlorides with

water http://www.youtube.com/watch?v=9VCSDuwoA8U

13.2.2 Explain why Scandium and Zinc are not considered to be transition elements. Sc and Zn do not form colored solutions; due to electronic configuration of their ions and the lack of partially filled d orbital.13.2.3 Explain the existence of variable oxidation number in ions of transition elements

http://www.youtube.com/watch?v=E3Ok1qaXK_g

First-row d-block elements13.2.1 List the characteristic properties of transition elements

http://www.youtube.com/watch?v=ZrmJuw_E1G0

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Electron Configurations of Cations of Transition Metals

When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals.

Fe: [Ar]4s23d6

Fe2+: [Ar]4s03d6 or [Ar]3d6

Fe3+: [Ar]4s03d5 or [Ar]3d5

Mn: [Ar]4s23d5

Mn2+: [Ar]4s03d5 or [Ar]3d5

13.2.4 Define the term ligand. Ligands are a species (atom or ion) that can donate an electron pair to a central transition metal atom/ion to form a dative covalent bond.Common ligands include H2O, CN-, OH- NH3 Cl-.Ligands must have a lone pair but they do not have to be negative - they can be neutral, but never positive.

13.2.5 Describe and explain the formation of complexes of d-block elements.

http://www.youtube.com/watch?v=Lmsn75HLViU

13.2.6 Explain why some complexes of d-block elements are colored

http://www.youtube.com/watch?v=2nLs0yJqRwk

13.2.7 State examples of the catalytic action of transition elements and compounds

http://www.youtube.com/watch?v=NIZVXVwvsrA

13.2.8 Outline the economic significance of catalysts in the Contact and Haber processes. Iron (Fe) in the Haber process: manufacture of ammonia-the raw material for fertilizers, plastics, drugs, etc. V2O5 in the Contact process: SO2 + O2 SO3 – for the manufacture of sulfuric acid, the world’s most important chemical.

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Compounds of the Noble Gases

A number of xenon compounds XeF4, XeO3, XeO4, XeOF4 exist.A few krypton compounds (KrF2, for example) have been prepared.

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Chemistry in Action: Discovery of the Noble Gases

Sir William Ramsay