Properties of Transition Metals

1. Properties of Transition Metals Science Eureka Sabbatical (Term 1) Group I

2. What are Transition Metals? • The electrons they use in chemical bondings are present in not just the valence shell. Between Group II and III

3. What are Transition Metals? • This is why they exist in several oxidation states. • The oxidation state is the difference between the number of electrons associated with an atom in a compound as compared with the number of electrons in an atom of the element. In ions, the oxidation state is the ionic charge. In covalent compounds the oxidation state corresponds to the formal charge. Elements are assumed to exist in the zero oxidation state. • Example: In NaCl the oxidation states are Na(+1) and Cl(-1); • In CCl4(carbon tetachloride)the oxidation states are C(+4) and each chlorine is Cl(-1)

4. Examples of Transition Metals • Copper • Manganese • Gold • Silver • Iron • Platinum • Titanium

5. Properties of Transition Metals • Good conductor of heat and electricity • Transition metals, have giant metallic structure • This structure allows valence electrons to move freely, and the electrons are delocalized, forming a“sea of electrons” • The free electrons can then carry electrical charge or thermal energy throughout the metal. • Malleable • The atoms are closely packed, when force is applied on the metal, the layers of atom can slip over each other. The atoms then settle into position again.

6. Properties of Transition Metals • High melting and boiling points • Strong forces holding the atoms together • The“sea of electrons”attract and hold the positive ions tightly together • More thermal energy is required to weaken or break the strong forces of attraction • High density • The atoms are closely packed, when force is applied on the metal, the layers of atom can slip over each other. The atoms then settle into position again.

7. Properties of Transition Metals • Good catalysts • A catalyst is a chemical substance that increases the rate of a chemical reaction • Transition metals are good catalysts because they can lend or withdraw electrons from the reagent, depending on the nature of the reaction. • The ability to interchange between the oxidation states and be a good source for electrons make transition metals good catalysts.

8. Properties of Transition Metals • Form coloured compounds • A substance will appear coloured if it absorbs light from a portion of the visible spectrum. • Ions with d orbital electrons appear coloured because energy from visible light is absorbed • Ions with no d orbital electrons are colourless, eg, Sc3+, Ti2+. • When white light passes through a solution of one of these ions, or is reflected off it, some colours in the light are absorbed. The colour you see is how your eye perceives what is left.

9. Properties of Transition Metals From left to right, aqueous solutions of: Co(NO3)2 (red); K2Cr2O7 (orange); K2CrO4 (yellow); NiCl2 (turquoise); CuSO4 (blue); KMnO4 (purple).

10. Properties of Transition Metals • Paramagnetism • Paramagnetism is a form of magnetism whereby certain materials are attracted by an externally applied magneticfield. Compounds are paramagnetic when they have one or more unpaired electrons • Paramagnetismin the transition elements is caused by the presence of unpaired electrons in the d sub-orbital. Diamagnetism is characteristic of compounds where all the electrons are paired. • The magnetic fields of paired electrons cancel out, so only unpaired electrons contribute to paramagnetism.

11. Properties of Transition Metals • Form alloys easily • The atomic radii of the transition elements are not much different from each other. As a result, they can very easily replace each other in the lattice and form solid solutions called alloys. • **The atomic radius is a measure of the size of its atoms, the distance from the nucleus to the boundary of the surrounding electrons.It decreases as you go left to right because of the greater amount of protons. The higher the atomic number, the greater number of protons. The protons will pull the electrons closer to its nucleus due to opp. charges thus resulting in a smaller atomic radius.

12. Properties of Transition Metals • Less Reactive • Less reactive compared with Group I and II elements • The atoms of transition metals do not give away their electrons as easily as atoms of the Group I and Group II metals do. The smaller atomic radii of transition metals means the valence shell electrons are more strongly attracted to the nucleus and therefore less easily removed resulting in higher first ionisation energies compared to Group I and II metals. So, transition metals are less reactive than alkali metals and alkaline-earth metals. • ** The first ionization energy is the energy required to remove one electron from the parent atom.

13. Example Uses of Transition Metals • Uses of Iron: • Iron catalysts are used in the Haber-Bosch Process to produce ammonia and the Fischer-Tropsch Process to convert carbon monoxide to hydrocarbons used for fuels and lubricants. • Strong but cheap: Automobile bodies and frames, food cans, building materials and machine parts • Iron (III) chloride is used in the treatment of sewage, as a dye for cloth, as a colouring agent for paint, an additive in animal feed, an in the manufacture of printed circuit boards. • Iron (II) sulfate is used to treat iron deficiency. It also removes very small sewage particles in water tanks.

14. Example Uses of Transition Metals • Uses of Copper: • Excellent conductor of electricity and heat • Thus used as wire cables, electric motors, • Also used in lightning rods, because these attract lightning and cause the electrical current to be dispersed rather than striking • Construction: Plumbing, roofing because copper is light, durable, water-proof • Alloy of copper and nickel-(cupronickel): More resistant to corrosion that is used in shipbuilding

15. Example Uses of Transition Metals • Uses of Titanium: • Surgical instruments, wheelchairs and crutches are all made out of titanium for high strength and low weight • Heat exchangers in desalination plants (which turn sea water into drinking water) are made from titanium as it is resistant to corrosion in sea water. • Many firearms are made from titanium as it is strong and lightweight. • Titanium alloy, which has high corrosion resistance, high specific strength, and good heat resistance, is used for different spacecraft parts • Aircraft uses titanium alloy because it is light and extremely strong at high temperatures. Titanium is used to strengthen the frame structure and contributes towards the technical advancement of jet engines.

16. Transition Metals Thank YOU