CHEMISTRY

Isotope can be defined as atoms of the same element with the same atomic number but different mass number. Isotope could also be defined as atoms of the same element with the same number of protons but different number of electrons.                                 Isotopy Isotopy is a phenomenon whereby atoms of the same element have the same atomic number but different mass number. Examples of elements that exhibit isotopy:     Class activities   1. An isotope is defined as atoms of the same element that have the same (a) mass number (b) atomic number (c) number of neutrons (d) number of shells. 2. Isotopes of an element differ in their (a) number of protons (b) number of electrons (c) number of neutrons (d) atomic number. 3. Which of the following is a pair of isotopes? (a) ¹²₆C and ¹⁴₆C (b) ¹²₆C and ¹⁴₇N (c) ²³₁₁Na and ²⁴₁₂Mg (d) ¹⁶₈O and ¹⁴₇N 4. The chemical p...

Steel is an alloy of iron and carbon, containing about 0.1% to 2.0% carbon. The composition of Steel are: 1. Iron (Fe) – the main metal 2. Carbon (C) – increases strength and hardness.                           Types of Steel 1. Mild Steel (Low Carbon Steel): It contains a small amount of carbon. it is soft, tough, and easy to shape. 2. Medium Carbon Steel:  Stronger and harder than mild steel. 3. High Carbon Steel:  Very hard and strong but less flexible. 4. Stainless Steel: It contains carbon, Iron, chromium and nickel. It resists rust and corrosion.                     Properties of Steel 1. It is strong and durable 2. It is hard and tough 3. It can withstand heavy loads 4. It can be shaped into different forms 5. It is resistant to wear 6. Stainless steel is resistant to rust and corrosion               ...

The General Gas Equation states that for a given mass of gas, the ratio of the product of pressure and volume to the absolute temperature remains constant, provided no gas is added or removed. Formula P₁ V₁ /T₁ = P₂ V₂ /T₂ Where: P₁ = Initial pressure V₁ = Initial volume T₁ = Initial absolute temperature (Kelvin) P₂ = Final pressure V₂ = Final volume T₂ = Final absolute temperature (Kelvin)  Note Temperature must be converted to Kelvin (K) before using the formula. K = °C + 273 Worked Example A gas occupies 4.0 dm³ at a pressure of 100 kPa and a temperature of 27°C. If the pressure is increased to 200 kPa and the temperature becomes 127°C, calculate the new volume. Solution P₁ = 100 kPa V₁ = 4.0 dm³ T₁ = 27 + 273 = 300 K P₂ = 200 kPa T₂ = 127 + 273 = 400 K P₁ V₁ /T₁ = P₂ V₂ /T₂ 100 × 4/300 = 200 ×  V₂/400 V₂= (100 × 4 ×400)/(300×200)  V₂= 2.67 dm³ Class activities  1. The General Gas Equation is obtained by combining: (a) Boyle's law and Charles's law (b)...

Charles's Law states that the volume of a given mass of gas is directly proportional to its absolute temperature, provided the pressure remains constant. V ∝ T (V is directly proportional to T) V/T = k where: V = Volume              T = Temperature               k = a constant value for a given                         sample of gas at a constant                     pressure  V₁/T₁ = k and V₂/T₂ = k, we can set them equal to each other. This gives us the most practical form of Charles's Law:                          V₁/T₁ = V₂/T₂ Where: V₁ = Initial volume T₁ = Initial temperature (in Kelvin) V₂ = Final volume T₂ = Final temperature (in Kelvin) Note : Temperatures must always be converted to Kelvin (K) because the law ...

Water is a colourless, odourless, tasteless and transparent liquid. A molecule of water is made up of 2 hydrogen ( H ) atoms and 1 oxygen ( O ) atom. The chemical formula of Water is  H₂O. Water is essential for the survival of all living things. It is the most abundant substance on the Earth's surface. Water is a compound formed when hydrogen combines chemically with oxygen.                 2H₂ + O₂→ 2H₂O                                       Sources of Water The sources of water include: Rain, Rivers, Streams, Lakes, Springs, Wells, Boreholes, Oceans and seas (salt water)               Types of water   The two types of water are: 1. Soft water  2. Hard water                       Soft water Soft water is a type of water that form lather ...

Oxygen is one of the most abundant and important elements on Earth. It is essential for respiration in humans, animals, and many other living organisms. Oxygen also supports combustion(burning). Chemical Symbol of oxygen: O Atomic Number of oxygen: 8 Mass number of oxygen: 16 Molecular Formula of oxygen: O₂                   Isotopes of oxygen  The isotopes of oxygen are: 1. Oxygen-16 (¹⁶₈O) 2. Oxygen-17 (¹⁷₈O) 3. Oxygen-18 (¹⁸₈O)                 Occurrence of Oxygen Oxygen occurs: 1. In the atmosphere as oxygen gas (about 21% of air). 2. In water (H₂O). 3. In rocks and minerals as oxides. 4. In living plants and animals.       Physical Properties of Oxygen 1. It is a colourless, odourless and tasteless gas 2. It is slightly soluble in water. 3. It is denser than air. 4. It exists as a diatomic molecule (O₂).       Chemical Properties of Oxygen 1. It suppor...

                        HYDROGEN   Hydrogen is a non-metallic element with the chemical symbol H and atomic number 1. It is the lightest and most abundant element in the universe.             Occurrence of Hydrogen Hydrogen occurs: I. In water (H₂O). II. In acids e.g. hydrochloric acid (HCl) and sulphuric acid (H₂SO₄). III. In hydrocarbons such as petroleum and natural gas. IV. In living organisms. V. In the Sun and other stars, where it is the main fuel for energy production. Physical Properties of Hydrogen 1. It is a colourless, odourless and tasteless gas 2. It is the lightest known gas. 3. It is less dense than air. 4. It is slightly soluble in water. 5. It is highly flammable. 6. It exists as diatomic molecules (H₂)                   Isotopes of hydrogen Isotopes are atoms of the same element that have the same atomic number but d...

                              pH pH  stands for the potential of hydrogen. It is a measure of the degree of acidity or alkalinity (basicity) of a solution. It is measured by an instrument called pH meter.                           pH SCALE  The pH scale ranges from 0 to 14; the lower and upper limits respectively. Note : 1. Substances with pH < 7 is  Acidic e.g.battery acid, vinegar, gastric juice etc 2. Substances with pH = 7 is Neutral e.g. Pure water, table salt etc 3. Substances with pH > 7 is Alkaline (Basic) e.g. Bile, sea water, soap solution, NaOH etc                 Importance of pH 1. pH helps to determine whether a substance is acidic or alkaline. 2. It is used in agriculture to test soil before planting crops. 3. Used in medicine to monitor body fluids. 4. H...

                                  ACIDS An acid is a substance that produces hydrogen ions (H⁺) when dissolved in water.                         Types of acids The two types of acids are: I. Organic acids II. Inorganic acids Organic acids occur naturally in plants and animals. Inorganic acids are called mineral acids, since they are produced from mineral ores. They are man- made. Examples of inorganic acids are: 1. Hydrochloric acid (HCl) 2. Trioxonitrate(V) acid (HNO₃) 3. Sulphuric acid (H₂SO₄) etc                   Properties of Acids 1.  Acids have sour taste. 2.  Acids turn blue litmus paper red. 3. Acids react with metals to produce hydrogen gas. 4. They conduct electricity in solution. 5. They have pH values less than 7.           ...

React and balance the following chemical equations: 1. FeCl₃(s) + NaOH → 2. FeSO₄ + NaOH → 3. Zn + HCl → 4. Mg + HCl → 5. Ca(OH)₂ + HNO₃ → 6. FeCl₂ + NaOH → 7. Al(s) + O₂(g) → 8. AgI + Na₂S → 9. CaCl₂ + Na₃PO₄ → 10. KOH + H₃PO₄ → 11. Hg(OH)₂ + H₃PO₄ → 12. CuO + H₂SO₄ → 13. CaCO₃ + H₂SO₄ → 14. KNO₃ + H₂CO₃ → 15. Na₃PO₄ + HCl → 16. TiCl₄ + H₂O → 17. C₆H₁₂O₆ + O₂ → 18. Al₂O₃ + H₂SO₄ → Balance the following chemical equations (1) P + O₂ → P₂O₅ (2) Na₂O + H₂O → NaOH (3) K + H₂O → KOH + H₂ (4) Fe + H₂O ⇌ Fe₃O₄ + H₂ (5) CaO + HCl → CaCl₂ + H₂O (6) Fe + Cl₂ → FeCl₃ (7) Al + H₂O → Al₂O₃ + H₂ (8) Al + H₂SO₄ → Al₂(SO₄)₃ + H₂ (9) Fe₂O₃ + H₂ → Fe + H₂O (10) C + H₂SO₄ → CO₂ + H₂O + SO₂ (11) Pb₃O₄ → PbO + O₂ (12) Al + O₂ → Al₂O₃ (13) NO + O₂ → NO₂ (14) ZnS + O₂ → ZnO + SO₂ (15) Pb₃O₄ + HCl → PbCl₂ + H₂O + Cl₂ (16) ZnO + NaOH → Na₂ZnO₂ + H₂O (17) H₂S + Cl₂ → S + HCl

                          Radicals   A radical is a group of atoms that acts as a single unit and carries either a positive or negative charge during a chemical reaction. Radicals behave as units and take part in the formation of chemical compounds. For example: SO₄²⁻ — Sulphate radical NO₃⁻ — Nitrate radical OH⁻ — Hydroxide radical NH₄⁺ — Ammonium radical               Types of Radicals The two types of radicals are: I. Positive radicals II. Negative radicals                   Positive Radicals These are radicals that carry a positive charge . Examples:             Negative Radicals These are radicals that carry a negative charge. Examples: Characteristics of Radicals A radical consists of two or more atoms in most common cases. The atoms in ...

Valency is the combining power of an element. It determines how an element combines with other elements to form compounds. CLASSIFICATION OF ELEMENTS BASED ON VALENCY Elements may have different valencies, as I. Monovalent elements  II. Divalent elements III. Trivalent elements IV. Tetravalent elements V. Pentavalent elements I. Monovalent Elements They are elements with a valency of 1. Examples: Potassium (K), Sodium (Na), Hydrogen (H), Fluorine (F), and Chlorine (Cl). II. Divalent Elements They are elements with a valency of 2. Examples: Calcium (Ca), Barium (Ba), Magnesium (Mg), Oxygen (O), and Zinc (Zn). III. Trivalent Elements They are elements with a valency of 3. Examples: Aluminium (Al), Iron (Fe³⁺), Boron (B), and Nitrogen (N). IV. Tetravalent Elements They are elements with a valency of 4. Examples: Carbon (C), Silicon (Si), and Lead (Pb⁴⁺). V. Pentavalent Elements They are elements with a valency of 5. Examples: Phosphorus (P), Arsenic (As), and Antim...

                                  SO₄  SO₄ is called Sulphate or Tetraoxosulphate(VI). Sulphate compounds contain the sulphate ion (SO₄²⁻). It has a valency of 2. Write the chemical formula of the following compounds: 1. Sodium sulphate (Valency: Na=1, SO₄=2) 2. Potassium sulphate (Valency: K=1, SO₄=2) 3. Calcium sulphate (Valency: Ca=1, SO₄=2) 5. Copper(II) sulphate (Valency: Cu=2, SO₄=2) 6. Magnesium sulphate (Valency: Mg=2, SO₄=2) 7. Zinc sulphate (Valency: Zn=2, SO₄=2) 8. Iron(II) sulphate (Valency: Fe=2, SO₄=2) 10. Ammonium sulphate (Valency: NH₄=1, SO₄=2) 11. Barium sulphate (Valency: Ba=1, SO₄=2) 12. Aluminium sulphate (Valency: Al=3, SO₄=2)                                     NO₃ NO₃ is called Nitrate or Trioxonitrate(V). Nitrate compounds contain the nitrate ion (NO₃⁻). It has a valency of 1....

CO₃ is called Carbonate or Trioxocarbonate(IV). Carbonate compounds contain the carbonate ion (CO₃²⁻). It has a valency of 2. Write the chemical formula of the following compounds. 1. Calcium carbonate  (Valency: Ca =2, CO₃=2) 2. Sodium trioxocarbonate(IV).    (Valency: Na=1, CO₃ =2) 3. Potassium carbonate  (Valency: K=1, CO₃ =2) 4. Magnesium carbonate  (Valency: Mg=1, CO₃=2) 5. Zinc carbonate  (Valency: Zn=2, CO₃=2) 6. Copper(I) carbonate  (Valency: Cu=1, CO₃ =2) 7. Iron(II) carbonate  (Valency: Fe=2, CO₃=2) 8. Lead(II) carbonate  (Valency: Pb=2, CO₃=2) 9. Barium carbonate  (Valency: Ba=2, CO₃ =2) 10. Lithium carbonate  (Valency: Li=1, CO₃=2) 11. Ammonium carbonate (Valency: (NH₄=1, CO₃=2)                      Assignment  Write the chemical formula of the following compounds 1. Copper(II) trioxocarbonate(IV).  (Valency: Cu=2, CO₃ =2) 2....

The Kinetic Theory of Matter states that all matter is made up of small particles that are in constant motion. The particles possess kinetic energy. The arrangement of these particles determine the physical state of the matter. It also explains the behavior of matter based on the motion of its tiny particles (atoms or molecules).       Properties of the states of matter The three states of matter are: 1. Solid state 2. Liquid State 3. Gaseous state                       Solid State 1. They have definite shape and volume 2. They have strong intermolecular forces 3. Their particles are closely packed and orderly  4. Their particles are Incompressible 5. They have high density 6. Particles vibrate about fixed positions Examples: Ice, iron, wood                       Liquid State 1. They have no definite shape (they take the shape of their con...

Chemical bond Chemical bonding is the formation of a chemical bond between two or more atoms to hold them together as a stable molecule resulting in a chemical compound. Chemical bond  is the force of attraction that holds atoms or ions together in a molecule or compound.       When atoms bond, they form molecules or compounds with lower energy and greater stability.           Types of Chemical Bonding  1. Electrovalent (Ionic) Bonding  2. Covalent Bonding 3. Metallic bonding          Electrovalent (Ionic) Bonding This is the type of bonding formed when one or more electrons are transferred from a metal atom to a non-metal atom.        The metal becomes a positive ion (cation), while the non-metal becomes a negative ion (anion). The electrostatic attraction between the oppositely charged ions forms the bond. e.g. NaCl, MgO etc Example : Formation of sodium chloride (NaCl) ...

React and balance the following chemical equations: 1. FeCl₃(s) + NaOH → 2. FeSO₄ + NaOH → 3. Zn + HCl → 4. Mg + HCl → 5. Ca(OH)₂ + HNO₃ → 6. FeCl₂ + NaOH → 7. Al(s) + O₂(g) → 8. AgI + Na₂S → 9. CaCl₂ + Na₃PO₄ → 10. KOH + H₃PO₄ → 11. Hg(OH)₂ + H₃PO₄ → 12. CuO + H₂SO₄ → 13. CaCO₃ + H₂SO₄ → 14. KNO₃ + H₂CO₃ → 15. Na₃PO₄ + HCl → 16. TiCl₄ + H₂O → 17. C₆H₁₂O₆ + O₂ → 18. Al₂O₃ + H₂SO₄ → Balance the following chemical equations (1) P + O₂ → P₂O₅ (2) Na₂O + H₂O → NaOH (3) K + H₂O → KOH + H₂ (4) Fe + H₂O ⇌ Fe₃O₄ + H₂ (5) CaO + HCl → CaCl₂ + H₂O (6) Fe + Cl₂ → FeCl₃ (7) Al + H₂O → Al₂O₃ + H₂ (8) Al + H₂SO₄ → Al₂(SO₄)₃ + H₂ (9) Fe₂O₃ + H₂ → Fe + H₂O (10) C + H₂SO₄ → CO₂ + H₂O + SO₂ (11) Pb₃O₄ → PbO + O₂ (12) Al + O₂ → Al₂O₃ (13) NO + O₂ → NO₂ (14) ZnS + O₂ → ZnO + SO₂ (15) Pb₃O₄ + HCl → PbCl₂ + H₂O + Cl₂ (16) ZnO + NaOH → Na₂ZnO₂ + H₂O (17) H₂S + Cl₂ → S + HCl