Lesson Note 1-4 PDF

**WEEK 1: INTRODUCTION TO CHEMISTRY** **ESSENTIAL QUESTIONS:** i. Define chemistry. ii. Mention FIVE branches of Chemistry. iii. Explain FOUR applications of chemistry. iv. Suggest THREE reasons why all students at the secondary school level should be made to study chemistry. **What is Ch...

**WEEK 1: INTRODUCTION TO CHEMISTRY** **ESSENTIAL QUESTIONS:** i. Define chemistry. ii. Mention FIVE branches of Chemistry. iii. Explain FOUR applications of chemistry. iv. Suggest THREE reasons why all students at the secondary school level should be made to study chemistry. **What is Chemistry?** Chemistry is the branch of science that studies the composition, structure, properties, uses and interactions of matter. An expert in the field of chemistry or one who studies chemistry is called a **CHEMIST.** **BRANCHES OF CHEMISTRY** There are several branches of chemistry. Here is a list of the main branches of chemistry, with an overview of what each branch of chemistry studies. i. ii. iii. iv. v. vi. vii. viii. ix. x. **CAREERS IN CHEMISTRY** 1. 2. 3. 4. 5. 6. 7. a. b. c. d. e. f. g. h. i. **Adverse effects of chemicals and chemical processes** 1. 2. 3. 4. 5. 6. **SCIENTIFIC METHODS:** It refers to the principles that guide scientific research and experimentation, and also the philosophic bases of those principles. Scientists are alert and inquisitive using their senses to observe what is happening around them. The methods used include: **LABORATORY APPARATUS** +-----------------+-----------------+-----------------+-----------------+ | For exact |     **Pipette** | There are |       **Pipette | | volume | | several styles | filler** | | measurements of | Description: | of fillers used | | | liquids. | Description: | to draw liquids |  | | graduation for | | one. Never draw | | | delivering one | | a liquid into a | | | exact volume. | | pipette with | | | Pipette on the | | your mouth. | | | right is | | | | | a **Mohr | | | | | pipette**. It | | | | | has graduations | | | | | for delivering | | | | | any number of | | | | | exact volumes. | | | | +=================+=================+=================+=================+ | Used in | **Filter | The Erlenmeyer | **Erlenmeyer | | conjunction | flask** | flask is used | flask** | | with a vacuum | | to contain | | | connection to a | Description: | reaction |  | +-----------------+-----------------+-----------------+-----------------+ | The flat bottom | **Flat bottom | The volumetric | **Volumetric | | flask is used | flask** | flask is used | flask** | | for boiling | | to make | | | liquids. | Description: | solutions. It |  | | | | the flask. A | | | | | solute is | | | | | placed into the | | | | | flask, then the | | | | | solvent is used | | | | | to bring the | | | | | total volume up | | | | | to the | | | | | graduation. | | +-----------------+-----------------+-----------------+-----------------+ | Beakers are the |     **Beaker** | Used to make | **Measuring | | most versatile | | accurate | cylinder** | | glassware in | Description: | measurements of | | | the lab and can | Description: | liquid volumes. |  | | graduations on | | breakage if | | | beakers should | | tipped over. | | | be used only | | Keep it near | | | for | | the top. | | | \"ballpark\" | | | | | estimates. | | | | +-----------------+-----------------+-----------------+-----------------+ | This dish is | **Evaporating | A watch glass |     **Watch | | used to recover | dish** | can be used | glass** | | dissolved | | like an | | | solids by | Description: | evaporating |  | | | | used to cover | | | | | beakers. | | +-----------------+-----------------+-----------------+-----------------+ | When attached |     **Support | When attached |     **Utility | | to the ring | ring** | to the ring | clamp** | | stand, this | | stand, this | | | iron ring is | Description: | clamp is used |  | | | | above the lab | | | | | table. | | +-----------------+-----------------+-----------------+-----------------+ | Crucibles are | **Crucible and | These tongs are |       | | used as a | cover** | used for |   **Crucible | | container when | | picking up | tongs** | | something | Description: | crucibles and | | | requires | Description: | crucible |  | +-----------------+-----------------+-----------------+-----------------+ | Used as a |     **Wire | Used to light a |       | | support for | gauze** | lab |   **Striker** | | beakers when | | burner. **Not** | | | placed across a | Description: |  a | | | support ring. | Description: | toy noisemaker | | | | wire gauze | during lab. | | +-----------------+-----------------+-----------------+-----------------+ | Used to grind | **Mortar and | Used to hold | **Test tube | | solids into | Pestle** | test tubes for | holder** | | powders. | | short periods | | | |  | | | +-----------------+-----------------+-----------------+-----------------+ | When lined with | **Filter | Used for | **Wash bottle** | | filter paper, | funnel** | rinsing solids | | | used to filter | | out of a | Description: | | suspended |  | | | +-----------------+-----------------+-----------------+-----------------+ | Used to | **Spatula or | Used to close | **Hose clamps** | | transfer solids | Chemical | hoses by | | | from their | spoon** | pinching them | Description: | | original | | together. | Description: | | container to a |  | | | +-----------------+-----------------+-----------------+-----------------+ | **Desiccators** | **Desiccator** | | | |  are | | | | | used to provide |  | | | | substance to | | | | | cool down. This | | | | | is critical in | | | | | quantitative | | | | | work where | | | | | moisture can | | | | | affect mass | | | | | results. A | | | | | common | | | | | desiccant is | | | | | anhydrous | | | | | calcium | | | | | chloride. | | | | | Coloured | | | | | indicator | | | | | crystals are | | | | | usually | | | | | included to | | | | | tell the user | | | | | the condition | | | | | of the | | | | | desiccant. A | | | | | grey colour in | | | | | the crystals | | | | | usually | | | | | indicates that | | | | | the desiccant | | | | | is dry and will | | | | | absorb | | | | | moisture. A | | | | | pink colour | | | | | usually means | | | | | that the | | | | | desiccant is | | | | | \"hydrated\". | | | | | When this | | | | | happens, the | | | | | water can be | | | | | removed by | | | | | heating it in | | | | | an oven. | | | | +-----------------+-----------------+-----------------+-----------------+ **ASSIGNMENT**: 1. 2. 3. 4. **WEEK 2: PARTICULATE NATURE OF MATTER** **OBJECTIVE**: Matter is anything that has mass and occupies space. The nature of matter is such that all matter is made up of discreet fundamental particles. These particles could be atoms, molecules, ions, electrons etc. Furthermore the particulate nature of matter suggests that matter is not entirely continuous and indivisible in space and that it can be differentiated. The other name for the \'particulate nature of matter\' is the \'atomic theory\'. **ATOMS:** An atom is the smallest particle of an element which can take part in a chemical reaction. OR An atom is the smallest part of an element that can ever exist and still possess the chemical properties of that element. **MOLECULES:** A molecule is the smallest particle of a substance that can exist alone and still retain the chemical properties of that substance. The number of atoms in each molecule of an element is the **atomicity** of the element. Examples of molecules are O~2~, H~2~, N~2~, Ne, Ar, P~4~, S~8~, O~3~, Mg etc. **IONS:** An ion is any atom or group of atoms which possesses an electric charge. There are two types of ions: i. ii. **Dalton's Atomic Theory** In 1808 John Dalton, an English Scientist proposed a number of theory on the nature of atoms of elements. These theories are called "Dalton atomic theory". 1\. All elements are made up of small indivisible particles called atoms. 2\. Atoms of elements can neither be created nor destroyed. 3\. Atoms of the same element are alike in all respect including mass and different from atoms of other elements. 4\. When atoms combine to form a molecule or a compound, they do so in simple whole number ratio. 5\. All chemical reactions are as a result of combination or separation of atoms. **Modifications to Dalton's Atomic Theory** **Theory 1:** That atom of elements are the smallest indivisible particle is no longer true in modern chemistry as "atoms are now known to consist of three fundamental sub particles". **Theory 2:** That atoms of elements can neither be created nor destroyed is no longer true in modern chemistry as "atoms of elements are now being destroyed and atoms of new element created during Nuclear reactions." **Theory 3:** That atoms of the same element are similar in all respect has been contradicted by the existence of isotope atoms of same element which have the same atomic numbers or number of protons but different mass numbers or number of neutrons. **Theory 4:** That atoms of different elements combined in simple whole number ratio has been proved wrong by the existence of large molecules of organic compounds in which atoms of their elements combined in large whole number ratio as in glucose. C~6~H~12~O~6~, Sucrose C~12~H~22~O~11~ and so on. **Table Showing Mass and Charges of the sub-particles of an atom** **Particles** **Relative mass** **Charge** **Position** --------------- ------------------- ------------ -------------------- Proton 1 +ve Nucleus Electron 1/1840 -ve Around the nucleus Neutron 1 No charge Nucleus 1. **Nuclide of Atom:** A **nuclide** is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of [protons](http://en.wikipedia.org/wiki/Protons), its number of [neutrons](http://en.wikipedia.org/wiki/Neutrons). It is given by the symbol of an atom or by a letter, which shows or expresses the mass number of the atom as the superscript number and the atomic number as subscript number. For example, the nuclide of sodium atom is given by ^23^~11~Na or ^23^~11~X where 23 = mass number and 11 = atomic number. The symbol or letter ^35^~17~X represent the nuclide of Cl atom. **2. Atomic Number:** The atomic number is the number of electrons or protons present in an atom. NOTE: Atomic number of atom of element is given by the subscript number in the nuclide of atom of an element e.g ~23~Na or ~23~X. **3. Mass Number:** The mass number gives the arithmetic sum of the number of protons and neutrons in the nucleus of atom of elements. It gives the mass of the atom i.e atomic mass of the element. **Mathematically:** Mass Number = No of protons + No of neutrons :. No of neutron = Mass No -- No of protons. NOTE: Mass number is represented by the superscript number in the nuclide of atom of element e.g. ^23^Na or ^23^X for sodium atom. **4. Atomic Mass:** Is the mass of 1 atom of an element. It is a whole number and does not give the accurate mass of an atom because it does not account for the mass of isotope atoms. **5.** **Relative atomic mass:** It is defined as the number of times the average mass of one atom of the element is heavier than one twelfth of the mass of one atom carbon -- 12 **Mathematically** R.A.M = [Average mass of 1 atom of element] 1/12 mass of 1 atom of carbon -- 12 **Relative Atomic Mass (R.A.M)** is usually expressed in fraction unlike the atomic mass which is a whole number. Relative atomic mass gives the accurate mass of an element because it accounts for the different masses and the relative abundance of the isotope atoms in an element. **6. Relative Molecular Mass (R.M.M):** is defined as the arithmetic sum of the atomic masses of all atoms of the elements present in a molecule or compound. **Vapour Density And Relative Molar Mass** Vapour density is defined as the number of times a given volume of a gas is as heavy as equal volume of hydrogen gas at the same temperature and pressure. **Mathematically:** V.D = [Mass of a given volume of a gas] Mass of equal volume of hydrogen gas V.D = [Mass of 1 molecule of a gas] Mass of 1 molecule of hydrogen gas V.D = [Relative molar mass of a gas] 2 :. Relative molar mass of gas = V.D. x 2 **ISOTOPY** **Isotopy** is the phenomenon whereby two or more atoms of the same element have the same atomic numbers but different mass numbers. **Isotopes** are atoms of the same element with the same atomic number but different mass numbers. This is due to the difference in their number of neutron. The relationship between the isotopic nuclides of an element is called isotopy. Examples of isotopes are: **Calculations on isotopy** **Example1**. Determine the atomic compositions of copper with atomic number 29 and having isotopes ^63^Cu and ^65^Cu. **Isotopes** **No of protons** **No of electrons** **No of neutrons** -------------- ------------------- --------------------- -------------------- ^63^Cu 29 29 34 ^65^Cu 29 29 36 **Example2.** The 2 isotopes of chlorine with mass numbers 35 and 37 exist in the ratio of 3:1, the lighter being more abundant. What is the relative atomic mass of chlorine? **Solution:** Isotopes: ~35~Cl ~37~Cl Isotopic ratio: 3 : 1 Sum of their ratio: 3 + 1 = 4 R.A.M. of chlorine = ([\$\\frac{3}{4}\$]{.math.inline} x 35) +[\$\\ (\\frac{1}{4}\$]{.math.inline} x 37) = 26.25 + 9.25 = 35.5 **ASSIGNMENT:** Answer questions 1, 6b and 7 on page 23 of the Essential chemistry for S.S.S. by I.A. Odesina **WEEK 3: ELEMENTS** **ESSENTIAL QUESTIONS:** i\. Define element ii\. State the classes of elements. iii. According to Robert Boyle, an Irish chemist, substances that resist chemical decomposition are said to be elements while substances that are easily decomposed by chemical means are said to be compounds thus, **Elements are chemical substances that cannot be split or decomposed into simpler units by any known chemical processes.** Element: - - - **Elements** are classified into two classes which are: metals and non-metals. **Metallic Elements** \* Metals are elements in which the atom of the element ionizes by losing its valence electron(s), to form positive ions called cations: Na Na^+^ + e^-^ Ca Ca^2+^ + 2e^-^ \* Metals exist in nature as aggregate of atoms and their names are represented by symbol. **Non-Metallic Elements** \* Non-metals are elements in which the atom of the elements ionizes by gaining electron(s) to form negative ions called anions. O + 2e^-^ O^2-^ \* Non-metals exist as molecules in nature and can be represented by chemical formula. **Symbols of Element** Jon Jakob, a Sweedish Chemist and Antoine Lavoisier, a French chemist were the first to use symbols to represent atom(s) of element(s), both the metal and non-metal elements. Jakob coined the symbol from the first letter or the first two or three letters of the English names of the elements. For examples, Al is from Aluminium, O is from Oxygen, Cl is from Chlorine and so on. In some cases symbols are derived from the Latin names of the elements e.g. **Au for Gold** is from Latin name Aurum, **Fe for Iron** is from Latin name Ferrum, **Pb for lead** is from Latin name Plumbum. **Hg for Mercury** is from Latin name Hydragyrum **K for Potassium** is from Latin name Kalium, **Na for Sodium** is from Latin name Natrium, **Ag for Silver** is from Latin name Argentum and so on. **Showing Symbols And Formula Of The 1 -- 20 Elements** **Atomic Number** **Names of Element** **Symbols of Atom** **Formula of Molecule** **Class of Element** ------------------- ---------------------- --------------------- ------------------------- ---------------------- 1 Hydrogen H H~2~ Non-metal 2 Helium He \- Non-metal 3 Lithium Li \- Metal 4 Beryllium Be \- Metal 5 Boron B \- Metal 6 Carbon C \- Non-metal 7 Nitrogen N N~2~ Non-metal 8 Oxygen O O~2~ Non-meteal 9 Fluorine F F~2~ Non-metal 10 Neon Ne \- Non-metal 11 Sodium Na \- Metal 12 Magnesium Mg \- Metal 13. Aluminium Al \- Metal 14. Silicon Si \- Non-metal 15 Phosphorous P P~4~ Non-metal 16 Sulphur S S~8~ Non-metal 17 Chlorine Cl Cl~2~ Non-metal 18 Argon Ar \- Non-metal 19 Potassium K \- Metal 20 Calcium Ca \- Metal Note: Cl~2~, O~2~, N~2~, H~2~, F~2~, exist as the diatomic gases as room temperature while He, Ne, Ar, Kr, Xe and Rn exist as mono atomic gases. **ASSIGNMENT:** 1. 2. **WEEK 4: MOLECULE** **ESSENTIAL QUESTIONS:** i. ii. iii. iv. v. A **molecule** is the smallest particle in a chemical [element](http://whatis.techtarget.com/definition/element) or [compound](http://whatis.techtarget.com/definition/compound) that can exist alone and possess the chemical properties of that element or compound. It is an electrically neutral group of two or more [atoms](https://en.wikipedia.org/wiki/Atom) held together by [chemical bonds](https://en.wikipedia.org/wiki/Chemical_bond). Molecules are distinguished from [ions](https://en.wikipedia.org/wiki/Ion) by their lack of electrical charge. In the [kinetic theory](https://en.wikipedia.org/wiki/Kinetic_theory) of [gases](https://en.wikipedia.org/wiki/Gas), the term *molecule* is often used for any gaseous particle regardless of its composition. According to this definition, [noble gas](https://en.wikipedia.org/wiki/Noble_gas) atoms are considered molecules despite being composed of a single non-bonded atom. A molecule may be [**homonuclear**](https://en.wikipedia.org/wiki/Homonuclear), that is, it consists of atoms of a single [chemical element](https://en.wikipedia.org/wiki/Chemical_element), as with [oxygen](https://en.wikipedia.org/wiki/Oxygen)(O~2~); or it may be [**heteronuclear**](https://en.wikipedia.org/wiki/Heteronuclear), a [chemical compound](https://en.wikipedia.org/wiki/Chemical_compound) composed of more than one element, as with [water](https://en.wikipedia.org/wiki/Water_(molecule))(H~2~O). Atoms and complexes connected by [non-covalent bonds](https://en.wikipedia.org/wiki/Non-covalent_interactions) such as [hydrogen bonds](https://en.wikipedia.org/wiki/Hydrogen_bond) or [ionic bonds](https://en.wikipedia.org/wiki/Ionic_bond) are generally not considered single molecules. Molecules are made up of [atom](http://searchcio-midmarket.techtarget.com/definition/atom)s that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of [electron](http://searchcio-midmarket.techtarget.com/definition/electron)s among atoms. The atoms of certain elements readily bond with other atoms to form molecules. Examples of such elements are oxygen and chlorine. The atoms of some elements do not easily bond with other atoms. Examples are neon and argon. Molecules can vary greatly in size and complexity. The element helium is a one-atom molecule. Some molecules consist of two atoms of the same element. For example, O~2~ is the oxygen molecule most commonly found in the earth's atmosphere; it has two atoms of oxygen. However, under certain circumstances, oxygen atoms bond into triplets (O~3~), forming a molecule known as ozone. Other familiar molecules include water, consisting of two hydrogen atoms and one oxygen atom (H~2~O), carbon (IV) oxide, consisting of one carbon atom bonded to two oxygen atoms (CO~2~ ), and tetraoxosulphate (VI) acid, consisting of two hydrogen atoms, one sulphur atom, and four oxygen atoms (H~2~SO~4~ ). The number of atoms in a molecule of an element/compound is its **atomicity.** **Element** **Symbol** **Atomicity** ------------------- ------------ ----------------- Helium He 1 or Monoatomic Neon Ne 1 or Monoatomic Hydrogen H~2~ 2 or Diatomic Nitrogen N~2~ 2 or Diatomic Hydrogen chloride HCl 2 or Diatomic Ozone O~3~ 3 or Triatomic Water H~2~O 3 or Triatomic Sulphur S~8~ Polyatomic Some molecules, notably certain proteins, contain hundreds or even thousands of atoms that join together in chains that can attain considerable lengths. Liquids containing such molecules sometimes behave strangely. For example, a [liquid](http://whatis.techtarget.com/definition/liquid) may continue to flow out of a flask from which some of it has been poured, even after the flask is returned to an upright position. Molecules are always in motion. In a [solid](http://whatis.techtarget.com/definition/solid) , the motion of the molecules can be likened to rapid vibration. In a liquid, the molecules can move freely among each other, in a sort of slithering fashion. In a [gas](http://whatis.techtarget.com/definition/gas) , the density of molecules is generally less than in a liquid or solid of the same chemical compound, and they move even more freely than in a liquid. For a specific compound in a given state (solid, liquid, or gas), the speed of molecular motion increases as the absolute temperature increases. **ASSIGNMENT:** 1. 2. - - - -