The Transition Elements: Types of ligand. Shapes and coordination numbers

Unidentate ligands: Ligands with only one donor atom, e.g. NH₃, Cl^-, F^- etc.

Bidentate ligands: Ligands with two donor atoms, e.g. ethylenediamine, C₂O₄^2-(oxalate ion) etc. 

Tridentate ligands: Ligands which have three donor atoms per ligand, e.g. (dien) diethyl triamine.

Hexadentate ligands: Ligands which have six donor atoms per ligand, e.g. EDTA. 

Chelating Ligands: Multidentate ligand simultaneously co-ordinating to a metal ion through more than one site is called chelating ligand. These ligands produce a ring like structure called chelate. Chelation increases the stability of complex. This effect is called chelation effect.

The bond angles of the ligands around the central atom depends on the number of times it bonds.

http://www.askiitians.com/iit-jee-co-ordination-compounds/ligands-and-its-types/#

https://www.boundless.com/chemistry/transition-metals/coordination-compounds/coordination-number-ligands-and-geometries/

The Transition Elements: Formation of complex ions

A complex ion has a metal ion at its center with a number other molecules or ions surrounding it.
They are attached to the central ion by coordinate (dative covalent) bonds.
The molecules or ions surrounding the central metal ion are called ligands.
The active lone pairs of electrons in the outer energy shell are used to form coordinate bonds with the metal ion.



http://www.chemguide.co.uk/inorganic/transition/features.html

The Transition Elements: Catalytic properties. Laboratory and industrial examples.

Transition metal catalysts can either be homogeneous or heterogeneous catalysts (they can be in the same physical state as the reactants or not).

Laboratory example:
2H2O2 --MnO2--> 2H2O +O2
MnO2 is the catalyst.

Industrial example:
Transition metals can be used in petroleum and polymer (plastics, fibers) industries.


http://www.sky-web.pwp.blueyonder.co.uk/Science/transitionmetalcatalysts.htm
http://global.britannica.com/EBchecked/topic/602775/transition-element/81115/Transition-metal-catalysts

The Transition Elements: Explanation of color of compounds. The colours of the major ions

When transition metals form compounds, the d-orbitals of the metal interact with the electron cloud of the ligands in a way that the d-orbitals do not all have the same energy. The way they are split depends on the geometry of the complex. When the d-orbital is not completely filled, it is possible to promote an electron from a lower energy d-orbital to a higher energy d-orbital by absorbing a photon of electromagnetic radiation with the right amount of energy. The right amount of energy usually happens to be within the visible region of the electromagnetic spectrum. So, the light that isn't absorbed is what we see as the color of the compound.

Name	Formula	Color	Picture
Copper(II) sulfate	CuSO4	White
Copper(II) sulfate pentahydrate	CuSO4 · 5H2O	Blue
Copper(II) benzoate	C14H10CuO4	Blue
Cobalt(II) chloride	CoCl2	Deep blue
Cobalt(II) chloride hexahydrate	CoCl2 · 6H2O	Deep magenta
Manganese(II) chloridetetrahydrate	MnCl2 · 4H2O	Pink
Copper(II) chloride dihydrate	CuCl2 · 2H2O	Blue-green
Nickel(II) chloride hexahydrate	NiCl2 · 6H2O	Green
Lead(II) iodide	PbI2	Yellow

http://www.wou.edu/las/physci/ch462/tmcolors.htm
http://en.wikipedia.org/wiki/Color_of_chemicals

The Transition Elements: Use of standard electrode potentials to predict reactions

Standard electron potentials (redox potentials) measure how easily a substance loses electrons. The more negative this value, the further the position of equilibrium is to the left.


The Mg will freely turn into Mg ions, and will be able to give electrons to the hydrogen ions producing hydrogen gas.



http://www.chemguide.co.uk/physical/redoxeqia/predict.html

The Transition Elements: Variable oxidation states. The common oxidation states

All transition metals except Sc are capable of having various oxidation states. The 4s electron are first used and then the 3d electrons.

This happens because the 4s and 3d electrons have similar energy.

The known oxidation states can be summarized by this table:





http://www.s-cool.co.uk/a-level/chemistry/transition-metals/revise-it/variable-oxidation-states

The Transition Elements: General physical & chemical properties and periodicity

• high melting point and boiling points
• conduct electricity and heat
• malleable and ductile
• low ionization energies
• wide range of oxidation states, but are all positive
• positive oxidation states allow for ionic and partially ionic compounds
• five d orbitals become more filled from left to right on periodic table

http://chemistry.about.com/od/elementgroups/a/transitionmetal.htm

The Transition Elements: Definition of transition element

A transition metal is an element which forms one or more stable ions which have incompletely filled d orbitals.

http://www.chemguide.co.uk/inorganic/transition/features.html

The Transition Elements: Electron configurations. Ionization energies and relative stability of ions

The main characteristic of the electron configuration of transition elements is that they have full outer sub-orbitals and the second outermost d sub-orbitals incompletely filled.
An exception to this is copper which loses one 4s orbital electron to the 3d suborbital in order to increase stability.

The ionization energies of transition elements remain fairly low even when the atomic number increases.

Transition metal ions have their electrons removed not from the higher energy orbitals, but from the valence shell orbitals.
Transition metals form one or more stable ions with a completely filled d orbital.

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Electronic_Configurations/Electron_Configuration_of_Transition_Metals_and_Ions%3A_Mn_vs._Cu
http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Ionization-of-Transition-and-Inner-Transition-Elements-904.html
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch12/trans.php

The Transition Elements: The first row d block (Sc to Zn.)

These transition metals have variable oxidation numbers, have high melting points, and are harder and denser than group 1 and 2 metals.
There is no significant change in atomic radii due to the repulsion between the 4s and 3d electrons.
However, Sc and Zn are not considered transition elements because they do not have a partially filled d subshell. They only have one possible oxidation state.

http://www.scribd.com/doc/56633626/13-2-First-Row-D-Block-Elements

Halogens: Hydrogen halides. Acidity and thermal stability

If you use the Bronsted-Lowry definition of an acid as a proton donor, hydrochloric, hydrobromic and hydroiodic acids are all acids. Hydrogen chloride, hydrogen bromide and hydrogen iodide dissolve in and react with water to give their respective acids, which are strong acids.
However, although hydrogen fluoride dissolves in water, hydrofluoric acid is a weak acid.

Hydrogen halides are colorless gases at room temperature. Hydrogen fluoride has a higher boiling point than the other halides because it can form hydrogen bonds. The other hydrogen halides increase boiling points as you go down the periodic table.

http://www.chemguide.co.uk/inorganic/group7/acidityhx.html

Halogens: Metal halides. Reaction with conc. sulphuric acid. Precipitation reactions with silver and lead ions. Tests for halide ions

Concentrated sulfuric acid, when reacted with metal halides, can act as either an acid or an oxidizing agent.
If it is acting as an acid, the concentrated sulphuric acid gives a hydrogen ion to the halide ion to produce a hydrogen halide.
e.g. NaCl + H2SO4 --> HCl + NaHSO4
If it is acting as an oxidizing agent, how it reacts with halides depends on the halide itself.
Concentrated sulfuric acid is not a strong enough oxidizing agent to oxidize fluoride or chlorine ions.
Bromide ions are strong enough to reduce concentrated sulfuric acid. It will reduce sulfuric acid to sulfur dioxide gas and it will be oxidized to bromine.
Iodide ions are stronger reducing agents than bromide ions, so they will reduce sulfuric acid to sulfur dioxide, then to sulfur, then to hydrogen sulfide. 

You can test for halide ions by using silver nitrate. If silver nitrate solution is added to water containing halide ions the silver halide is precipitated. This is because silver halides are insoluble in water.
The same occurs for lead nitrate; the lead halide is precipitated.




http://www.chemguide.co.uk/inorganic/group7/halideions.html
http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/ionic_compounds/ionicanalysisrev5.shtml
http://www.nuffieldfoundation.org/practical-chemistry/silver-and-lead-halides

Halogens: Special properties of Fluorine

Fluorine is the most electronegative element.
It is so electronegative that it can react with noble gases like xenon.
Fluorine is the most chemically reactive element.
It is the smallest substituent after hydrogen.
It can form stronger bonds with carbon than hydrogen can.
Fluorine is poisonous and gaseous, and is pale yellow-green.

http://crab.rutgers.edu/~alroche/FCh2.pdf
http://www.chemicalforums.com/index.php?topic=472.0
http://www.lenntech.com/periodic/elements/f.htm

Halogens: Oxidation numbers and oxidizing reactions of the halogens

The oxidation number of halogens is always -1 except when with other halogens or with oxygen.
However, the oxidation number of fluorine will always be -1 no matter what it is in a compound with.

Halogens are all potentially oxidizing agents.
Fluorine is such a powerful oxidising agent that you can't reasonably do solution reactions with it.
Oxidizing ability decreases as you go down the group.


http://www.chemistry.co.nz/redox_oxi_aa.htm
http://www.chemguide.co.uk/inorganic/group7/halogensasoas.html

Halogens: Industrial preparation, lab preparation and test for chlorine gas

Chlorine is prepared commercially by the electrolysis of sodium chloride. If molten sodium chloride is places in an electrolytic device and the power source is turned on, the negatively charged chlorine ions Cl- move toward the positively charged electrode. A container can be placed above the anode (the positively charged electrode) to collect the chlorine gas produced by the reaction.
2NaCl --> 2Na + Cl2 

In the lab preparation of chlorine, manganese dioxide is heated with concentrated hydrochloric acid HCl. A redox reaction takes place in which manganese chloride, water and chlorine are produced.
4HCl + MnO2 --> MnCl2 + 2H2O + Cl2

Chlorine gas can be tested for with moist blue litmus paper which will turn red in the presence of chlorine gas.

Prentice Hall Chemistry
http://www.gcsescience.com/itestchlorinegas.htm

Halogens: Reaction of the halogens with metals, non-metals, and alkalis.

The binary compounds of halogens with hydrogen or metals are salts known as halides.
metal + halogen → metal halide

Interhalogen compounds are compunds made up of two halogens. Their properties are usually intermediate of the two halogens.

Halogenated compounds, or organic halides, are organic compounds that have a halogen on it.

Halogens react with alkali metals to form salts. This happens because alkali metals have one electron in their outer shell that they want to give away and halogens have seven electrons in their outer shell and they want to gain one electron.


http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group7rev2.shtml
https://www.boundless.com/chemistry/nonmetallic-elements/halogens/halogen-compounds/
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements/Case_Studies/Reactions_of_Main_Group_Elements_with_Halogens

Halogens: Group trend in properties e.g. volatility and reactivity.

Melting points and boiling points increase as you go down the group.
Fluorine and chlorine are gases at room temperature, bromine is a liquid and iodine and astatine are solids. There is a trend in physical state from gas to liquid to solid as you go down the group.
The color of the halogens get darker as you go down the group. Fluorine is very pale yellow, chlorine is yellow-green, and bromine is red-brown. Iodine crystals are shiny purple, but easily turn into a dark purple vapour when are warmed up
Volatility and reactivity of the halogens decrease as you go down the group.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group7rev1.shtml

Halogens:General physical & chemical properties

Halogens are diatomic. They exist naturally as molecules in groups of two atoms.
They have low melting and boiling points.
They are the most reactive of nonmetals.
They are nonmetals so they so not conduct electricity.
They have high effective nuclear charge so they are highly electronegative.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group7rev1.shtml
https://www.boundless.com/chemistry/nonmetallic-elements/halogens/properties-halogens/

Alkali Metals: Comparison of groups Ι and ΙΙ.

Alkali metals are softer than alkaline earth metals.
Alkali metals will have an oxidation state of +1 while alkaline earth metals will have an oxidation state of +2. This is because alkali metals have one electron in their outer shell while alkaline earth metals have two.
Alkaline earth metals will react directly with nitrogen to form nitrides, while alkali metals will not.
Alkali metals will react with ammonia to form an amide, while alkaline earth metals will react with ammonia at a low temperature to form a hexamines.
Alkaline earth metal carbonates will decompose easily upon heating, while alkali metals are more stable.
Alkali metal nitrates will decompose evolving oxygen, while alkaline earth metal nitrates will evolve NO2 and O2.
Sulfates formed by alkali metals are very soluble, while sulfates of alkaline earth metals are not so soluble.
Alkali metal bicarbonates are less soluble than their carbonates, and vice versa for alkaline earth metal bicarbonates and carbonates.
Fluorides, carbonates, phosphates and oxalates of alkali metals are soluble, while those of alkaline earth metals are not.

http://www.tutorsonnet.com/chemistry_homework_help/inorganic_chemistry/periodic_table/S_block/differences_between_alkali_and_alkalineearth_metals_assignment_help_tutoring.htm

Alkali Metals: Special properties of Lithium. Diagonal relationship with Magnesium.

Lithium is the first element in the alkali metal group. It is the lightest solid metal, soft, silvery-white, has a low melting point and is reactive, though not as reactive or as soft as the other alkali metals.

It has a high specific heat (calorific capacity), the huge temperature interval in the liquid state, high termic conductivity, low viscosity and very low density.

Diagonal relationship with magnesium
Lithium resembles magnesium because of their similar size.
Both Li and Mg are harder and have a higher melting point than the other elements in their respective groups.
Hydroxides and nitrates of both Li and Mg decompose when heated to form an oxide. Hydroxides of Li and Mg are both weak alkali.
Bicarbonates of Li and Mg are more soluble than their carbonates, while the other elements in their groups have more soluble carbonates.
Li and Mg have many more similar properties.

http://www.lenntech.com/periodic/elements/li.htm#ixzz2TuxsUbHP
http://www.transtutors.com/chemistry-homework-help/s-and-p-block-elements/diagonal-relationship-li-and-mg.aspx

Alkali Metals: Reaction with oxygen, water, chlorine, hydrogen and acid

Reaction with oxygen
The alkali metals will react quickly with the oxygen in the air to create a white oxide.
e.g.
4K(s) + O₂(g) → 2K₂O(s)
All except lithium react further to form yellow peroxides
2K₂O(s) + O₂(g) → 2K₂O₂(s)

Reaction with water
The alkali metal will react vigorously with water to form a hydroxide and also produce hydrogen gas. The hydroxides dissolve in water to form a basic solution.
e.g.
2Li(s) + 2H2O(l) --> 2LiOH(aq) + 2H2(g)

Reaction with chlorine
The alkali metal will react vigorously with chlorine gas and produce a white crystalline chloride salt.
e.g.
2Na(s) + Cl2(g) --> 2NaCl(s)

Reaction with hydrogen
The alkali metals react with hydrogen gas to form hydrides
e.g.
2Li(s) + H2(g) --> 2LiH(s)

Reaction with acid
Alkali metals react with acid to form a salt and hydrogen gas.
e.g.
2Na(s) + 2HCl(aq) --> 2NaCl(aq) + H2(g)

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group1rev4.shtml
http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Group-IA-Alkali-Metals-544.html
http://wiki.answers.com/Q/What_is_the_reaction_of_alkali_metals_with_an_acid

Alkali Metals: Group Trend in Properties

As you go down the group:

• their melting points decrease
• their densities increase
• the number of electron shells increases, and by using the density formula, mass/volume, you 'll realise that by increasing the number of electron shells, you are increasing the number of electrons, protons and neutrons as well, which obviously have masses, and thus it will increase the density as it will definitely surpass the increase in volume.
• they become softer
• they become more reactive

"The alkali metals - trends in reactivity."BBC GCSE Bitesize. N.p., n.d. Web. 2 May 2013. <http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/patterns/groupsrev2.shtml>

http://wiki.answers.com/Q/Why_does_the_density_group_1_elements_increase_as_you_go_down_the_group

The Alkali Metals: General Physical and Chemical Properties and Why They Have Those Properties

• one electron in their outer shell
• they are in the first column of the periodic table
• malleable
• the atoms that are closely packed together can roll over into new positions without breaking the metallic bonds.
• ductile
• same reason as why they are malleable
• good conductors of heat and electricity
• The delocalised electrons are free to move throughout the structure
• softer than most other metals
• they have large atomic radii relative to their atomic mass, and so their metallic bonds are weak
• very reactive
• they only have one electron in their outer shell, so they always want to be bonded to something else
• reactions with water form hydroxides and dissolve to form alkaline solutions, which turn universal indicator purple
• they will always want to react with water in this way

Bentor, Yinon. "Periodic Table: Alkali Metals." Chemical Elements.com. N.p., n.d. Web. 2 May 2013. <http://www.chemicalelements.com/groups/alkali.html>

"The alkali metals - trends in reactivity."BBC GCSE Bitesize. N.p., n.d. Web. 2 May 2013. <http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/patterns/groupsrev2.shtml>

http://www.chemguide.co.uk/atoms/structures/metals.html

http://www.meritnation.com/ask-answer/question/why-are-alkali-metals-soft-also-why-are-they-good-reduc/the-s-block-elements/2930064