75 chemistry key point you must know as a student preparing for waec ,jamb post utme ,Jupeb etc .
Some times brilliant student failed examination due to inadequate preparations prior the exam day for the reason that I know chemistry very well there is no questions set on chemistry that I will not tackle for that I will not border myself reading chemistry all day . My dear constant reading help a lot , "that tinny rope you felt cannot pull down a hen have pull down many elephants be wise "
Below are some chemistry key point for jamb, post utme ,jupeb, waec and nNeco .
1.A radical is a group of atoms that functions as a single unit in chemical reactions.
2. A homologous series is a family of organic compound with a regular structural pattern, in which each successive member differs in its molecular formula by -CH2- Group.
3: A functional group is atom ,a radical or a bond common to a particular homologous series. It is a he functional group that determines the main chemical properties of the series.
4: A molecule is the smallest particle of a substance that can normally exist and still retain the chemical properties of that substance.
5: Atom is the smallest particle of of an element that can take part in chemical reactions.
Read also;six-things-you-should-do-to-have retentive memory as student
6: Do you know all atoms of elements are represented by symbol while ion, molecules and radical are represented by formulae so and thing you see in chemistry represented by symbol know it is an atom.
7: Activating group is any substituent on a benzene ring that causes the rate of electrophilic aromatic substitution to be greater than that for benzene.
8: An ion is any atom or group of atoms which possess an electric charge.
9: cracking is used to obtain petrol from the heavier, or less volatile fractions of crude oil.
10:Do you know the grade of petrol is measured on an octane number scale .High grade petrols have octane numbers nearer 100.while low grade petrols have octane numbers nearer 0.
11: The empirical formula of a compound gives only the simplest whole number ratio of the component elements in the compound. Some time the empirical and molecular formula of a compound are the same. And some cases, the empirical formula is a simple multiple of the empirical formula.
12: The law of conservation of mass states that matter is neither created nor destroyed during a chemical reaction but changes from one form to another.
13: The law of Definite proportions States that all pure sample of a particular chemical compound contain similar elements combined in the same proportion by mass.
14: Do you know alcoholic fermentation is a metabolic pathway that convert glucose to two molecules of ethanol and two molecules of carbon iv oxide.
15: The law of multiple proportion States that if two elements combined to form more than one chemical compound, then the various masses of one element which combine separately with a fixed mass of the other element are in simple multiple ratio.
16: The law of Reciprocal proportions States that the masses of several elements A,B,C which combine separately with fixed mass of another element D,are the same as,or simple multiples of, the masses in which A,B,C themselves combine with one another.
17:The number of atoms in a single molecule is known as its atomicity.
18: The molar mass of a substance is it's relative molecular mass expressed in gram.
19: Valency is the combination of power of an element or radical. It is actually the oxidation number assigned to the element or group of elements.
20 : Alkanes family are those saturated
Hydrocarbons whose carbon atoms are arranged in an open chain. They have the molecular formula (CnH2n+2) and are alternatively described as aliphatic hydrocarbons. Alkanes with one or four carbon atoms are gases while others are liquids and soft solids . Alkanes are neutral, slightly soluble in water .it undergo combustion and substitution reactions.
21:Alkenes are unsaturated
hydrocarbons that contain a carbon to carbon double bond .They have the molecular formula (CnH2n) and can undergo addition reactions due to the existence of double bonds. Due to also higher carbon to hydrogen ratio, alkenes gives a more smoky flame on combustion than alkanes.
22:Alkynes are unsaturated hydrocarbons that contain one or more carbon to carbon triple bonds. They have a higher degree of unsaturation than the alkenes and their molecular formula is (CnH2n-2) . They undergo addition reactions.
23:The alkyl group is a group derived from removing a hydrogen from an alkane.
24: Amino acids are compounds that contain both an amino group and a carboxyl group.
25:An amide is a compound in which an acyl (RCO- or ArCO-) group is bonded to a trivalent nitrogen atom.
26:An Arene is an aromatic hydrocarbon. An Aryl group is a group derived from an Arene by removal of an H; the symbol is Ar.
27:Aufbau's principle States that orbitals fill in order of increasing energy, from lowest to highest .
28: An Azeotrope is a mixture with constant composition and a boiling point that is different from that of any of its component.
29:Contributing structures are representations of a molecule, ion,or radical that differ only in the distribution of valence electrons by resonance.
30: Carbonation is an anion in which carbon has an unshared pair of electrons and bears a negative charge .It is also a species in which a carbon atom has only six electrons in its valence shell and bears a positive charged.
31: Chain propagation is a step in a chain reaction characterized by the reaction of a reactive intermediate and a molecule to give a new reactive intermediate and a new molecule.
32:Chain termination is a step in a chain reaction that involves destruction of reactive intermediaries.
33:Chain initiation is a step in chain reaction characterized by formation of reactive intermediaries ( anion, radical or cations) from non- radical or non-charged molecule.
34:Cis-trans isomers are isomers that have the same order of attachment of their atoms but different arrangement of their atoms in space due to the presence of either a ring or a carbon-carbon double bond.
35:Electronegativity is a measure of force of an atom's attraction for electrons it shares with another atom in a chemical bond.
36:Electrophile is any electron deficient species that can accept a pair of electrons from a nucleophile to form a new convalent bond; a Lewis acid.
37: Endothermic reaction is a reaction in which the energy of the product is higher than the energy of the reactants ; a reaction in which heat is absorbed.
39: Exothermic reaction is a reaction in which the energy of the product is lower than the energy of the reactants;reaction in which heat is liberated.
40: Alpha decay of an isotope gives a product two places to the left in the periodic table .
41: Beta decay of an isotope gives a product one place to the right of the periodic table.
42: The half - life of a radioactive isotope is the time it takes to lose half its radioactivity.
45: Fatty acid is a long ,unbranched chain carbonxylic acid .most commonly of 12 to 12 carbons .derived from the hydrolysis of animal fat.vegetable oils, or phospholipids of biological membranes.
46:Gay- Lussac's law of combining volumes states that when gases combine together they do so in volumes that are in a simple whole number ratio to each other and to the product ( if it is a gas)
47: Avogadro's theory States that under the same conditions of temperature and pressure,equal volumes of all gases contain the same number of molecule.
48: Dalton's law of partial pressure States that the total pressure exerted by a mixture of gases is the sum of the pressures that the individual gases woulg exert if they were to occupy the same volume alone.
49: Hund's law rule states that when orbital of equivalent energy are available but there are not enough electrons to fill all of them completely, then one electron is added to each equivalent orbital before a second electron is added to any of them.
50:Markovnikov's rules States that in the addition of HX,H2O,or ROH to an alkene, hydrogen adds to the carbon of the double bond having the greater number of hydrogens.
51: Hydrogen bonding is the attractive interaction between dipoles when the positive end of one of the dipoles is a hydrogen atom bonded to an atom of high electronegativity (most commonly F,O, or N) and the negative end of the other dipole is an atom with a lone pair of electrons(most Commonly F,O ,or N).
52:Non bonding electrons are valence electrons not involved in forming covalent bonds that is unshared electrons.
53:Ionization potential is the minimum energy required to remove an electron from an atom or molecule to a distance where there is no electrostatic interaction between ion and electron.
54: Ion bond is a chemical bond resulting from the electrostatic attraction of an anion and a cation .
55: The energies of electrons in atoms are quantized,that is the electrons exist in a set of energy levels .The values of the energy levels are governed by the principal quantum,n.
56:Do you know matter can show the properties of both waves and particles ,depending on the type of experiment that is performed.
De Broglie's equation (MV= h/ wavelength) sum up the wave particle duality ;where MV is the momentum (a particle- like property) .
Read also;physics- topics andt-all-their-formulas
57: In all ideal gases there are no intermolecular forces and therefore, no tendency for the gas to liquefy .
58: Charles's law state that the volume of a given mass of a gas is directly proportion to the absolute temperate in kelvin provided the pressure is constant.
59:The ideal gas law is pV=nRT, where n is the number of moles of gas and R is the gas constant.
60: Bonds broken means that heat is taken in while Bond made simply means heat is given out.
61:Bond energy is the energy needed to break a covalent bond completely.
62:Polymorphism occurs when a substance can exist in two or more forms in the same state. Allotropy is polymorphism in elements.
63:Enthalpy is a heat Change that takes place at constant pressure. It is also a state function; that's the change in its value depends on the initial and final state only not on what happens between those states.
64:Oxidation is the gain in oxygen; loss of hydrogen; the loss of electrons; the increase in oxidation number, Reduction is the converse of oxidation while an unreacted element has an oxidation number of 0.
65: A buffer solution keeps its pH approximately constant when small amount of an acid or alkali are added.
66: Do you know a metal with the most negative electrode potentials are the best reducing agents.
67:Binding energy is the energy released during the formation of a nucleus from its constituents.
68:At equilibrium, the reactants are changing into products at the same rate as the products are reacting back to give the reactants; that's rate of forward reaction is equal to backward reaction.
69:Hard water contains magnesium ions,Mg2+ and calcium ions,Ca2+, which give precipitate (ppt) with soap ,and deposits of insoluble magnesium and calcium carbonate after hard water is boiled.
To remove hardness of water pass it (water) through an ion exchange column
70: Nuclear fusion is the process whereby two or more light nuclei unite to form a heavier nucleus,with a release of energy and radiation .
71:Nuclear fission is the process in which a heavy nucleus is split into two or more lighter nuclei, with a release of energy and radiation.
72: A liquid with high vapour pressure will boil at a lower temperature than a liquid with lower vapour pressure.
73: That means the higher the vapour pressure of a liquid ,the more volatile the liquid becomes.
74:Graham's law of diffusion States that the rate of diffusion of a gas is inversely proportional to the square root of its density.
75: Le Chatelier's principle States that if a constraint is placed on an equilibrium mixture, then the equilibrium will shift so as to oppose the constraint .
Some times brilliant student failed examination due to inadequate preparations prior the exam day for the reason that I know chemistry very well there is no questions set on chemistry that I will not tackle for that I will not border myself reading chemistry all day . My dear constant reading help a lot , "that tinny rope you felt cannot pull down a hen have pull down many elephants be wise "
Below are some chemistry key point for jamb, post utme ,jupeb, waec and nNeco .
1.A radical is a group of atoms that functions as a single unit in chemical reactions.
2. A homologous series is a family of organic compound with a regular structural pattern, in which each successive member differs in its molecular formula by -CH2- Group.
3: A functional group is atom ,a radical or a bond common to a particular homologous series. It is a he functional group that determines the main chemical properties of the series.
4: A molecule is the smallest particle of a substance that can normally exist and still retain the chemical properties of that substance.
5: Atom is the smallest particle of of an element that can take part in chemical reactions.
Read also;six-things-you-should-do-to-have retentive memory as student
6: Do you know all atoms of elements are represented by symbol while ion, molecules and radical are represented by formulae so and thing you see in chemistry represented by symbol know it is an atom.
7: Activating group is any substituent on a benzene ring that causes the rate of electrophilic aromatic substitution to be greater than that for benzene.
8: An ion is any atom or group of atoms which possess an electric charge.
9: cracking is used to obtain petrol from the heavier, or less volatile fractions of crude oil.
10:Do you know the grade of petrol is measured on an octane number scale .High grade petrols have octane numbers nearer 100.while low grade petrols have octane numbers nearer 0.
11: The empirical formula of a compound gives only the simplest whole number ratio of the component elements in the compound. Some time the empirical and molecular formula of a compound are the same. And some cases, the empirical formula is a simple multiple of the empirical formula.
12: The law of conservation of mass states that matter is neither created nor destroyed during a chemical reaction but changes from one form to another.
13: The law of Definite proportions States that all pure sample of a particular chemical compound contain similar elements combined in the same proportion by mass.
14: Do you know alcoholic fermentation is a metabolic pathway that convert glucose to two molecules of ethanol and two molecules of carbon iv oxide.
15: The law of multiple proportion States that if two elements combined to form more than one chemical compound, then the various masses of one element which combine separately with a fixed mass of the other element are in simple multiple ratio.
16: The law of Reciprocal proportions States that the masses of several elements A,B,C which combine separately with fixed mass of another element D,are the same as,or simple multiples of, the masses in which A,B,C themselves combine with one another.
17:The number of atoms in a single molecule is known as its atomicity.
18: The molar mass of a substance is it's relative molecular mass expressed in gram.
19: Valency is the combination of power of an element or radical. It is actually the oxidation number assigned to the element or group of elements.
20 : Alkanes family are those saturated
Hydrocarbons whose carbon atoms are arranged in an open chain. They have the molecular formula (CnH2n+2) and are alternatively described as aliphatic hydrocarbons. Alkanes with one or four carbon atoms are gases while others are liquids and soft solids . Alkanes are neutral, slightly soluble in water .it undergo combustion and substitution reactions.
21:Alkenes are unsaturated
hydrocarbons that contain a carbon to carbon double bond .They have the molecular formula (CnH2n) and can undergo addition reactions due to the existence of double bonds. Due to also higher carbon to hydrogen ratio, alkenes gives a more smoky flame on combustion than alkanes.
22:Alkynes are unsaturated hydrocarbons that contain one or more carbon to carbon triple bonds. They have a higher degree of unsaturation than the alkenes and their molecular formula is (CnH2n-2) . They undergo addition reactions.
23:The alkyl group is a group derived from removing a hydrogen from an alkane.
24: Amino acids are compounds that contain both an amino group and a carboxyl group.
25:An amide is a compound in which an acyl (RCO- or ArCO-) group is bonded to a trivalent nitrogen atom.
26:An Arene is an aromatic hydrocarbon. An Aryl group is a group derived from an Arene by removal of an H; the symbol is Ar.
27:Aufbau's principle States that orbitals fill in order of increasing energy, from lowest to highest .
28: An Azeotrope is a mixture with constant composition and a boiling point that is different from that of any of its component.
29:Contributing structures are representations of a molecule, ion,or radical that differ only in the distribution of valence electrons by resonance.
30: Carbonation is an anion in which carbon has an unshared pair of electrons and bears a negative charge .It is also a species in which a carbon atom has only six electrons in its valence shell and bears a positive charged.
31: Chain propagation is a step in a chain reaction characterized by the reaction of a reactive intermediate and a molecule to give a new reactive intermediate and a new molecule.
32:Chain termination is a step in a chain reaction that involves destruction of reactive intermediaries.
33:Chain initiation is a step in chain reaction characterized by formation of reactive intermediaries ( anion, radical or cations) from non- radical or non-charged molecule.
34:Cis-trans isomers are isomers that have the same order of attachment of their atoms but different arrangement of their atoms in space due to the presence of either a ring or a carbon-carbon double bond.
35:Electronegativity is a measure of force of an atom's attraction for electrons it shares with another atom in a chemical bond.
36:Electrophile is any electron deficient species that can accept a pair of electrons from a nucleophile to form a new convalent bond; a Lewis acid.
37: Endothermic reaction is a reaction in which the energy of the product is higher than the energy of the reactants ; a reaction in which heat is absorbed.
39: Exothermic reaction is a reaction in which the energy of the product is lower than the energy of the reactants;reaction in which heat is liberated.
40: Alpha decay of an isotope gives a product two places to the left in the periodic table .
41: Beta decay of an isotope gives a product one place to the right of the periodic table.
42: The half - life of a radioactive isotope is the time it takes to lose half its radioactivity.
45: Fatty acid is a long ,unbranched chain carbonxylic acid .most commonly of 12 to 12 carbons .derived from the hydrolysis of animal fat.vegetable oils, or phospholipids of biological membranes.
46:Gay- Lussac's law of combining volumes states that when gases combine together they do so in volumes that are in a simple whole number ratio to each other and to the product ( if it is a gas)
47: Avogadro's theory States that under the same conditions of temperature and pressure,equal volumes of all gases contain the same number of molecule.
48: Dalton's law of partial pressure States that the total pressure exerted by a mixture of gases is the sum of the pressures that the individual gases woulg exert if they were to occupy the same volume alone.
49: Hund's law rule states that when orbital of equivalent energy are available but there are not enough electrons to fill all of them completely, then one electron is added to each equivalent orbital before a second electron is added to any of them.
50:Markovnikov's rules States that in the addition of HX,H2O,or ROH to an alkene, hydrogen adds to the carbon of the double bond having the greater number of hydrogens.
51: Hydrogen bonding is the attractive interaction between dipoles when the positive end of one of the dipoles is a hydrogen atom bonded to an atom of high electronegativity (most commonly F,O, or N) and the negative end of the other dipole is an atom with a lone pair of electrons(most Commonly F,O ,or N).
52:Non bonding electrons are valence electrons not involved in forming covalent bonds that is unshared electrons.
53:Ionization potential is the minimum energy required to remove an electron from an atom or molecule to a distance where there is no electrostatic interaction between ion and electron.
54: Ion bond is a chemical bond resulting from the electrostatic attraction of an anion and a cation .
55: The energies of electrons in atoms are quantized,that is the electrons exist in a set of energy levels .The values of the energy levels are governed by the principal quantum,n.
56:Do you know matter can show the properties of both waves and particles ,depending on the type of experiment that is performed.
De Broglie's equation (MV= h/ wavelength) sum up the wave particle duality ;where MV is the momentum (a particle- like property) .
Read also;physics- topics andt-all-their-formulas
57: In all ideal gases there are no intermolecular forces and therefore, no tendency for the gas to liquefy .
58: Charles's law state that the volume of a given mass of a gas is directly proportion to the absolute temperate in kelvin provided the pressure is constant.
59:The ideal gas law is pV=nRT, where n is the number of moles of gas and R is the gas constant.
60: Bonds broken means that heat is taken in while Bond made simply means heat is given out.
61:Bond energy is the energy needed to break a covalent bond completely.
62:Polymorphism occurs when a substance can exist in two or more forms in the same state. Allotropy is polymorphism in elements.
63:Enthalpy is a heat Change that takes place at constant pressure. It is also a state function; that's the change in its value depends on the initial and final state only not on what happens between those states.
64:Oxidation is the gain in oxygen; loss of hydrogen; the loss of electrons; the increase in oxidation number, Reduction is the converse of oxidation while an unreacted element has an oxidation number of 0.
65: A buffer solution keeps its pH approximately constant when small amount of an acid or alkali are added.
66: Do you know a metal with the most negative electrode potentials are the best reducing agents.
67:Binding energy is the energy released during the formation of a nucleus from its constituents.
68:At equilibrium, the reactants are changing into products at the same rate as the products are reacting back to give the reactants; that's rate of forward reaction is equal to backward reaction.
69:Hard water contains magnesium ions,Mg2+ and calcium ions,Ca2+, which give precipitate (ppt) with soap ,and deposits of insoluble magnesium and calcium carbonate after hard water is boiled.
To remove hardness of water pass it (water) through an ion exchange column
70: Nuclear fusion is the process whereby two or more light nuclei unite to form a heavier nucleus,with a release of energy and radiation .
71:Nuclear fission is the process in which a heavy nucleus is split into two or more lighter nuclei, with a release of energy and radiation.
72: A liquid with high vapour pressure will boil at a lower temperature than a liquid with lower vapour pressure.
73: That means the higher the vapour pressure of a liquid ,the more volatile the liquid becomes.
74:Graham's law of diffusion States that the rate of diffusion of a gas is inversely proportional to the square root of its density.
75: Le Chatelier's principle States that if a constraint is placed on an equilibrium mixture, then the equilibrium will shift so as to oppose the constraint .
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