Notes, summaries, assignments, exams, and exercises for Chemistry for Baccalaureate

Fundamental Concepts of Atomic Structure

The Bohr Atomic Model and Energy Levels

The Bohr atom only allows electrons to move in certain, quantized orbits around the nucleus. The lowest energy level corresponds to the orbit closest to the nucleus. As the orbit moves away from the core, the energy levels increase.

Hydrogen Spectra Explanation

The interaction of electrons with energy explains the hydrogen spectra:

• The electron absorbs energy when moving from a lower energy level to a higher energy level.
• When passing from a higher level to a lower level, the electron emits energy in the form of radiation (a photon).
• The energy absorbed or emitted by the photon equals the energy difference between the levels.
• The frequency of the emitted or absorbed radiation

Chemical Kinetics and Reaction Rate

The branch of chemistry dealing with the speed of reactions is known as chemical kinetics. It investigates the stages or phases of the reaction mechanism and studies the factors that can affect this speed.

Defining Reaction Rate

The speed of a reaction (or reaction rate) is defined as the amount of reactant that disappears per unit time in this reaction.

Reaction Systems

• Homogeneous System: The reaction occurs throughout the volume of the mixture.
• Heterogeneous System: The reaction occurs only at the interfaces. The reaction rate depends on the surface area common to both phases.

Factors Influencing Reaction Speed

Several factors significantly influence the rate at which a chemical reaction proceeds:

• Concentration

Mol

The unit of amount of substance in the SI. It is the amount of substance that contains as many basic entities as there are atoms in 12 g of the isotope carbon-12.

Avogadro's Number (NA)

One mole contains Avogadro's number of particles: NA = 6.022045 × 10²³.

Molar Mass (M)

Mass of one mole of atoms or molecules. The numerical value of molar mass in grams matches the value of the mass in amu of its formula.

Molar Volume

Volume of 1 mole of a substance at a certain temperature (the temperature must be stated), whether solid, liquid, or gas.

Following Avogadro's principle, 1 mole of gas occupies the same volume when measured under the same conditions of pressure (p) and temperature (T), irrespective of the gas. Under standard conditions (0 °C and...

Burette: Precision Volume Measurement

The burette is a **glass device** used to measure volumes with high accuracy. It consists of a graduated cylinder marked from top to bottom in cm³ (milliliters). Its primary advantage is allowing the precise dispensing of liquid drop by drop, controlled by a **stopcock** (key) located at the bottom. This stopcock regulates the flow, making it essential for titrations.

Volumetric Pipette (Bulb Pipette)

These are long glass tubes featuring an **enlargement (bulb)** in the central part. The lower section is finished sharply. Volumetric pipettes are designed to measure and transfer a single, fixed volume of liquid with high precision.

Graduated Pipette (Measuring Pipette)

Graduated pipettes are narrow glass tubes...

Nuclear Physics Fundamentals

The atomic nucleus is formed by nucleons (protons and neutrons). The atomic number (Z) defines the mass.

Nuclide Classifications

• Isotopes: Nuclides with the same number of protons but a distinct number of neutrons.
• Isobars: Nuclides with the same mass number (A) but a distinct number of protons and neutrons.
• Isotones: Nuclides with the same number of neutrons but a different number of protons.

Fundamental Forces of Nature

• Gravitational Force: Exerted between two particles with mass. It is always attractive and responsible for the existence of planets and stars. It is a weak, long-range interaction.
• Electromagnetic Force: Exerted between two electrically charged particles. It can be attractive or repulsive and is responsible

Dipole-Dipole and Dispersion Forces

Dipole-dipole forces are intermolecular forces established between the positive dipole of one molecule and the negative dipole of another. The polarity of a diatomic molecule is greater the larger the electronegativity difference.

London Dispersion Forces are intermolecular forces established between molecules due to the formation of instantaneous dipoles as a consequence of the movement of electrons. The intensity of these forces depends on the polarizability of the molecule and its size; these factors depend, in turn, on the number of electrons in a molecule.

Properties of Molecular Substances

Molecular substances can occur at any state of aggregation at room temperature. Their properties include:

• Melting and

Chemical Bonding: Principles and Types

Chemical bonding refers to the forces acting between two atoms that keep them together to form stable chemical species.

Covalent Bonds

Formed between non-metal atoms that attract electrons to complete their octet. Atoms share electrons because neither tends to yield them.

Characteristics:

• Low melting and boiling points due to weak intermolecular forces.
• Poor conductors of electricity as electrons are fixed within the molecule.
• Soluble in nonpolar solvents such as CCl₄, CS₂, or C₆H₆.

Ionic Bonds

Formed between metals (M) and non-metals (NM). The metal tends to donate electrons, while the non-metal captures them, resulting in electron transfer.

Characteristics:

• High melting and boiling points due to strong

Electron Configurations of Selected Elements

• 1: 1s¹ (H) (1)
• 2: 2s² (Be) (2)
• 3: 3d¹ 4s² (Sc) (4)
• 4: 3d² 4s² (Ti) (4)
• 5: 3d³ 4s² (V) (4)
• 6: 3d⁵ 4s¹ (Cr) (4)
• 7: 3d⁵ 4s² (Mn) (4)
• 8: 3d⁶ 4s² (Fe) (4)
• 9: 3d⁷ 4s² (Co) (4)
• 10: 3d⁸ 4s² (Ni) (4)
• 11: 3d¹⁰ 4s¹ (Cu) (4)
• 12: 3d¹⁰ 4s² (Zn) (4)
• 13: 2s² 2p¹ (B) (2)
• 14: 2s² 2p² (C) (2)
• 15: 2s² 2p³ (N) (2)
• 16: 2s² 2p⁴ (O) (2)
• 17: 2s² 2p⁵ (F) (2)
• 18: 1s² (He) (1)

Atomic Mass and Spectra Formulas

Atomic mass: (Total mass of isotope × abundance %) / 100 (in grams/atoms).

Wave Relations: c = λ × ν | E = h × ν

Atomic spectra: 1 / λ = R (1.097 × 10⁷) × (1 / n₁² - 1 / n₂²)

Frequency (ν): ν = E / h | Wavelength (λ): λ = c / ν

Electron Affinity

Electron Affinity is defined as the energy that a neutral gaseous atom in its ground...

What is a Dosage Form?

A dosage form may be defined as a blend of drugs and additives, produced in a definite physical form, size, and shape suitable for administration by a particular route.

Key Properties of Dosage Forms

• Economical
• Provides protection to the drug substance.
• Provides a better therapeutic effect.
• Easy to identify.
• Conceals bitter taste or odor.
• Easy to use and handle.
• Easy to store.
• Stable during use.

Importance and Need for Dosage Forms

The need for dosage forms, or their importance, is outlined below:

1. To protect the drug substance from oxidation, reduction, and hydrolysis (e.g., coated tablets, sealed ampules).
2. To provide a safe and convenient delivery of accurate dosage.
3. To mask the bitter, salty, or obnoxious taste or odor of a drug substance

Extraction of Zinc (Zn)

Major Ores of Zinc

• Zinc blende (ZnS)
• Calamine (ZnCO₃)
• Zincite (ZnO)

Zinc is primarily extracted from calamine and zinc blende ores.

Extraction from Calamine Ore

Zinc oxide is obtained by calcining calamine:

ZnCO₃ → ZnO + CO₂↑

Zinc metal is then obtained by heating zinc oxide (ZnO) with coal powder:

ZnO + C → Zn + CO↑

Extraction from Zinc Blende

Zinc oxide (ZnO) is obtained by roasting concentrated zinc blende at high temperatures in the presence of air:

2ZnS + 3O₂ → 2ZnO + 2SO₂↑

The resulting ZnO is reduced using the carbon method described above.

Purification of Zinc

The zinc obtained is impure and is purified via electrolysis. A pure aluminum sheet serves as the cathode, while impure zinc acts as the anode in...