Pharmaceutical Analytical Chemistry - Lecture 1 2024 PDF

# Pharmaceutical Analytical Chemistry-1 ## **Lecture 1** Associate Professor Dr Heba Wagdy ## **Objectives** - Define what is meant by chemistry - Define what is meant by Analytical chemistry - Classification of matter. - Physical and Chemical change. - Define solution. - Difference between accu...

# Pharmaceutical Analytical Chemistry-1 ## **Lecture 1** Associate Professor Dr Heba Wagdy ## **Objectives** - Define what is meant by chemistry - Define what is meant by Analytical chemistry - Classification of matter. - Physical and Chemical change. - Define solution. - Difference between accuracy and precision. - Define an atom and its components. - Components of the atom. - Periodic table. - Practice Questions. ## **I- The Science of Chemistry** - Chemistry is the study of matter, its properties and the changes it undergoes. - Matter is anything that occupies space and has mass. - Substance is a form of matter that has a definite composition and distinct properties. - Examples: Water, silver, etc. ## **II- Analytical Chemistry** - It is often described as the area of chemistry responsible for characterizing the composition of matter, both qualitatively (what is present) and quantitatively (how much is present). ## **III- Classification of matter** The diagram shows matter as a central concept, with two main branches: chemical composition and physical state. The left side shows mixtures, with different properties of components, subdivided into heterogeneous (non uniform throughout) and homogeneous (uniform throughout). The right side shows pure substances with distinct properties, subdivided into elements (simplest substance) and compounds (two or more elements/kinds of atoms). The physical state branch describes the states of matter: gas (evaporate, boil, resublimate, sublimate, condense), liquid (melt, solidify), and solid. ## **III- Classification of matter (Cont.)** ### **An element** - Is a type of matter that cannot be broken down into simpler substances by chemical means. - Can be defined by its symbol and they are listed in the periodic table. - Examples: Copper Cu (cuprum), iron Fe (ferrum) .....etc. ### **A Compound** - Is a substance that is composed of two or more other elements chemically united in fixed proportions. - Examples: Water - Note: The properties of compounds are very different from those of the elements they contain. ## **IV- Physical and Chemical Changes** ### **Physical Change** - Some of the physical properties of the sample may change, but its composition remains unchanged e.g. melting of ice or sugar dissolved in water. ### **Chemical change** - One or more kinds of matter are converted to new kinds of matter with different compositions e.g. burning of paper (C, H, O) .....main combustion products are CO2 & H2O as steam or digestion. ## **V- Solution** - A solution is a homogeneous mixture of 2 or more substances. - When one substance (The Solute) dissolves in another (The Solvent), particles of the solute disperse throughout the solvent. ## **V- Solution (Cont.)** ### **Solute** - Could be electrolytes or non-electrolytes ### **Electrolytes** - When the electrolyte solute is dissolved in water, the solution conducts electric current when an electric current is passed through it. - The molecules of electrolytes, when dissolved in water, dissociate into ions, and these ions conduct the current in electrolytes by migration. - For example: Most of the acid, bases and salts. - The higher the percentage of dissociation, the higher the strength of the electrolytes. - MgSO4 ↔ Mg2+ + SO42- - HCl ↔ H+ + Cl- ### **Non-Electrolytes** - When the non-electrolyte is dissolved in water, it does not conduct electric current when an electric current is passed through its solution. - For example: Organic materials as glucose, mannose, ethanol. ## **VI- Precision and accuracy** ### **Precision** - Refers to how closely measurements of the same quantity come to each other. - Example: How a measurement is uncertain, ± 0.1 or ± 0.01, etc. ### **Accuracy** - Refers to how close an experimental observation lies to the true value. ## **VII- Define an atom** - It can be defined as the smallest particle that still characterizes an element and can enter into a chemical reaction. ## **VII- Define an atom (Cont.)** ### **John Dalton's theory** - In 1808, an English scientist, John Dalton, developed the atomic model of matter which suggests the following: - An element is composed of tiny particles called atoms. Atoms of the same element show the same properties while atoms of different elements show different properties. - In an ordinary chemical reaction, atoms move from one substance to another but no atom of any element disappears or is changed into an atom of another element. - Compounds are formed when atoms of two or more elements combine. ## **VII- Define an atom (Cont.)** - A molecule (compound) is an aggregate of two or more atoms in a definite arrangement held together by chemical forces - H2 H2O NH3 CH4 - A diatomic molecule contains only two atoms - H2 N2 O2 Br2 HCI CO - A polyatomic molecule contains more than two atoms - O3, H2O, NH3, CH4 ## **VII- Define an atom (Cont.)** ### **Some important laws** ### **Law of conservation of mass** - "Matter is neither created nor destroyed in a chemical reaction." - The total amount of matter present before a chemical reaction is always the same as the total amount after. - The diagram shows two molecules of carbon and four molecules of oxygen reacting to produce one molecule of carbon dioxide and two molecules of water. - CH4 + 2O2 → CO2 + 2H2O ### **Law of multiple proportions** - The masses of one element that combine with a fixed mass of the second element are in a ratio of small whole numbers. - The diagram compares carbon dioxide and carbon monoxide molecules, each showing a central carbon atom bonded with oxygen. ## **VIII- Components of the atom** The diagram shows a generic atom with a central nucleus and electrons circling the nucleus. - Protons (positively charged) - Neutrons (no charge) - Electrons (negatively charged) - The no. of protons = The no. of electrons so the atom is neutral in charge. - The number of protons is equal to the atomic number of the atom. ## **VIII- Components of the atom (Cont.)** - An ion is an atom, or group of atoms, that has a net positive or negative charge. ### **Cation** - Ion with a positive charge - If a neutral atom loses one or more electrons, it becomes a cation. - Na atom → Na+ ion + e- (11p+, 11e-) → (11p+, 10 e-) - Ca atom → Ca2+ ion + 2e- (20p+, 20e-) → (20p+, 18e-) - The diagram shows a sodium atom losing an electron to form a sodium cation. ### **Anion** - Ion with a negative charge - If a neutral atom gains one or more electrons, it becomes an anion. - Cl atom + e- → Cl- ion (17p+, 17 e-) →(17p+, 18 e-) - O atom + 2e- → O2- ion (8p+, 8e-) → (8p+, 10e-) - The diagram shows a chlorine atom gaining an electron to form a chloride anion. ## **VIII- Components of the atom (Cont.)** The diagram shows the atomic structure notation for oxygen. - **A:** Mass number = A = Z + N - **Z:** Atomic number = number of protons - **N:** Neutron number ### **Atomic number (Z):** - It is the number of protons inside the nucleus of the atom of an element. - It is a basic property of the element. ### **Atomic mass (A) / (Atomic weight) / (Mass number)** - It is the number of protons and neutrons inside the nucleus of the atom. ## **IX- Periodic Table** The diagram shows a basic table and a diagram to exemplify the concepts of periods (rows) and groups (columns) in the periodic table. ## **IX- Periodic Table(Cont.)** The diagram shows a basic periodic table showing the main groups, transition metals, lanthanides, and actinides. ## **Practice Questions (Cont.)** ### **Question 1** Classify each of the following as element, compound or mixture: - Platinum - Table salt - Ethyl alcohol - Sugar - Seawater - Blood ### **Question 2** Does each of the following describe a physical change or a chemical change? - The helium gas inside a balloon tends to leak out after a few hours. - Photosynthesis in the growth of plants. - A spoonful of table salt dissolves in a bowl of soup. ### **Question 3** If 3 students are asked to determine the mass of a piece of copper wire. Each student repeated the experiments twice and the results were as follow: | Student | Experiment 1 | Experiment 2 | Average Value | | ---------- | ------------- | ------------- | -------------- | | Student A | 1.964 g | 1.978 g | 1.971 g | | Student B | 1.969 g | 1.970 g | 1.969 g | | Student C | 2.000 g | 2.002 g | 2.001 g | If the true value of the wire is 2.000 g. Describe the results of each of the 3 students in terms of Accuracy and Precision. ### **Question 4** Fill the following table: | Symbol | No. of protons | No. of neutrons | No. of electrons | Net charge | | -------- | --------------- | --------------- | ---------------- | ----------- | | | 33 | 42 | | 3+ | | 128Te2- | | | 54 | | | | 16 | 16 | 16 | | | | 81 | 123 | | 1+ | | 195Pt | | | | | ### **Question 5** State example for: - Main group elements - Alkali metals - Alkaline earth metals - Transition metals - Halogens - Noble gases.