SPM Form 4 Chemistry Notes — Chapter 4『4.6』Transition Elements

4.6 Transition Elements

 Transition metal is a block of metallic elements in between Group 2 and 13 in the Periodic Table.

 They are much less reactive than the alkali metals.

 They do not react as quickly with water or oxygen as alkali metals.

Some general physical characteristics

All transition elements are metals. Therefore they have the all the physical properties of metals such as：

✔ high melting and boiling points

✔ hard, high density

✔ high tensile strength

✔ high electrical conductivity

✔ shinny surfaces, ductile, malleable

✔ good conductor of heat

［Tensile strength］▷ the ability of metals to stay in their shape without breaking when a force is applied to it.

［Ductile］▷ the ability of metals to be stretched into wires without cracking or breaking them

［Malleable］▷ the ability of metals to be bent into a new shape.

High melting and boiling points

▶ The bond between atoms of metals is called metallic bond and usually it is a very strong bond.

▶ Thus all the transition metals have high melting point and boiling point

Form coloured compounds and ions

✈ Transition elements tend to form coloured compounds either in solid form or dissolved in a solvent.

Ions	Colour
Fe2+	Light green
Fe3+	Brown
Ni2+	Green
Cr3+	Green
Mn2+	Light pink
Cu2+	Blue
Co2+	Pink
MnO4-	Purple
CrO42-	Yellow
Cr2O72-	Orange

Catalytic properties

➷ A catalyst is a substance that speeds up a reaction but itself does not change chemically after a reaction

➷ Many transition metals are used directly as catalysts in industrial chemical processes.

Transition elements / its compound	Uses
Platinum	Ostwald Process in the manufacture of nitric acid
Nickel	Catalyst for “hydrogenation” in the margarine industry
Iron powder	Haber Process in the manufacture of ammonia
Vanadium(V) oxide	Contact Process in the manufacture of sulphuric acid

Variable oxidation state

✎ A transition elements can have a variable oxidation state, which means it can form more than one ion.

✎ for example, iron(II), Fe²⁺ and iron(III), Fe³⁺ , copper(I), Cu⁺ and copper(II), Cu²⁺

Forming a complex ions

◆ Transition elements can form complex ions.

◆ A complex ion is a polyatomic ions (positive or negative) consisting of a central metal ion with other group bonded to it.

Reactivity Series & Electrochemical Series

List of Some Common Elements

Periodic Table of the Elements

Chemistry Definition List

Element – a substance consists of one type of atom.

 Compound – a substance consists two or more elements that are chemically bonded (molecule or ions).

 Atom – smallest particle of an element.

 Molecule – a group of two or more atoms.

 Ion – a positively charged / negatively charged particle.

 Boiling point - Temperature at which liquid changes to gas under standard pressure.

 Melting point - Temperature at which solid changes to liquid under standard pressure.

 Isotopes – atoms of the same element with same proton number but different nucleon numbers.

 Matter（solid，liquid，gas）

 Particles（atom，molecules，ions）

 Subatomic particle – proton，neutron，electron

 Number of neutron（√），neutron number（×）

 Proton number – the number of proton in its atom.

 Nucleon number – the total number of proton and neutron in its atom.

 Relative atomic mass of an element = the average mass of one atom of an element/((1/12) x the mass of one carbon-12 atom).

 Relative molecular mass of an element = the average mass of one atom of an molecule/((1/12) x the mass of one carbon-12 atom).

 Molecule formula – compound shows the actual number of atoms of each element that are present in a molecule of the compound.

 Empirical formula – compound shows the simplest whole number ratio of atoms of each element in the compound.

 Mole – amount of substance that contains as many particles as the number of atoms in exactly 12 g of carbon-12 the symbol of mole is mol.

 One mole – Avogadro constant – 6.02 x 1023

 Group (Periodic Table) – vertical columns of element (similar chemical properties).

 Periods (Periodic Table) – horizontal rows of element.

 Valence electrons – electrons that occupy the outermost shell.

 Ionic bond – bond formed through the transfer of electrons between atoms of metal and non-metal to achieve the stable octet electron arrangement.

 Ionic compound – consist of positive ions and negative ions which are held by strong electrostatic forces of attraction.

 Covalent bond – bond formed through the sharing of electrons between atoms of non-metal to achieve the stable duplet or octet electron arrangement.

 Covalent compound (also simple molecular structure) – consists of neutral molecules which are held by weak intermolecular forces (Van der Waals).

 Electrolysis – The process of breaking down chemical compounds via the use of electric current.

 Anion – Negatively charged ions.

 Cation – Positively charged ions.

 Halogen – salt former with metals.

 Alkali (base) – chemical substance which ionizes in water to produce hydroxide ions, OH^-.

 Acid – chemical substance which ionizes in water to produce hydrogen ions, H⁺ or hydroxonium ions, H₃O⁺.

 pH – degree of acidity or alkalinity of a solution. Scale ranges from 0 to 14.

 pH value – measure of the concentration of hydrogen ions, H⁺ / hydroxide ions,OH^-.

 Strong alkali – ionises (dissociates) completely in water to form high concentration of hydroxide ions, OH^-.

 Weak alkali – ionises (dissociates) partially in water to form low concentration of hydroxide ions, OH^-.

 Strong acid – ionises (dissociates) completely in water to form high concentration of hydrogen ions, H⁺.

 Weak acid – ionises (dissociates) partially in water to form low concentration of hydrogen ions, H⁺.

 Neutralisation – the reaction between acid and base to produce salt and water only.

 Titration – a experiment used to determine the volume of acid needed to neutralize a fixed volume and molarity of alkali in a conical flask with the help of an acid-base indicator to detect the end point of the neutralization.

 Salt – a ionic compound formed when the hydrogen ion , H⁺ from acid is replaced by a metal ion / ammonium ion , NH₄⁺.

 Alloy – The compound that is formed by mixing metals with other elements.

 Polymer – long chain molecules made up by monomer (repeating unit).

 Rate of reaction –speed at which reactant are converted into products in a chemical reaction.

 Effective collision (Collision theory) – collision that results in a chemical reaction where the particles collide with the correct orientation and are able to achieve the activation energy.

 Catalyst – a chemical substances that provide an alternative path to lower the activation energy and increase the rate of reaction.

 Positive catalyst – increases the rate of reaction & lower the activation energy.

 Negative catalyst – decreases the rate of reaction & higher the activation energy.

 Homologous series – organic compounds (families) with similar formulae and properties.

 Organic compounds – carbon-containing compound. Carbon atoms form covalent bonds.

 Inorganic compounds – compounds from non-living things which do not contain the element carbon.

 Saturated hydrocarbons – hydrocarbons containing only single bonds between all carbon atoms.

 Unsaturated hydrocarbons – hydrocarbons containing at least one carbon-carbon double or triple bond.

 Isomer – Molecule that has same molecular formula but different structural formula.

 Esterification – esters are produced.

 Vulcanisation – a process of hardening  of natural rubber by adding sulphur compounds.

 Redox reaction – chemical reactions involving oxidation and reduction occurring simultaneously.

 Exothermic reaction – chemical reaction that release heat to the surroundings.

 Endothermic reaction – chemical reaction that absorbs heat from the surroundings.

 Heat of precipitation – the heat change when one mole of a precipitate is formed from their ions in aqueous solution.

 Heat of displacement – the heat change when one mole of a metal is displaced from its salt solution by a more electropositive metal.

 Heat of neutralisation – the heat change when one mole of water is formed from the reaction between an acid and an alkali.

 Heat of combustion – the heat change when one mole of a substance is completely burnt in excess oxygen.

 Flavouring – improve the taste or smell of food and restore taste loss due to food processing.

 Stabilisers – help to mix two liquids that usually do not mix together so that they form an emulsion.

 Thickeners – substances that thicken food and give the food a firm, smooth and uniform texture.