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

History of the Periodic System

As elements became known, scientists began to classify them based on their properties. This led to several attempts at organization:

Early Classification Attempts

• 1. Metals and Nonmetals

  The earliest distinction was made between metals and nonmetals as more elements were discovered.

• 2. Dobereiner's Triads

  Johann Wolfgang Dobereiner proposed classifying elements in groups of three, known as triads. In a triad, the middle element's atomic mass was approximately the average of the other two, and its chemical properties were intermediate between the elements at the ends.

• 3. Newlands' Law of Octaves (1863)

  John Newlands classified elements in groups of seven. He observed that every eighth element had similar characteristics

Atomic Structure and Quantum Concepts

Notation: Z (Atomic Number) = Protons; A (Mass Number) = Protons + Neutrons.

• Cation: Positive charge, loses electrons.
• Anion: Negative charge, gains electrons.

Radiation and Energy Calculations

Frequency: f = c / λ (where c = 3 × 10⁸ m/s).

Planck's Constant: E = h × f (h = 6.63 × 10^-34 J·s).

Energy Levels: ΔE = E_f - E_i = -K / n².

• Absorption: Inf → Sup (Energy +).
• Emission: Sup → Inf (Energy -).

Isotopes and Quantum Numbers

Isotopes: Same atomic number (Z) but different atomic mass (A).

• n (Principal): Energy level (1, 2, 3...).
• l (Angular Momentum): Orbital shape (0 to n-1).
• m_l (Magnetic): Orientation (-l to +l).
• m_s (Spin): Electron spin (+½, -½).

Orbital Types

• l = 0: s²
• l = 1: p⁶
• l = 2: d¹⁰
• l = 3: f¹⁴

Electron Configuration

Möller

National University: Santiago Antunez de Mayolo

Course: General Chemistry

Subject: Introduction to the Periodic System II

School: Agricultural Engineering

Teacher: Victor Martinez Montes

Members:

• Alva Matilla Jesus

1. Title

Chemical Bonding I

2. Aim

• Distinguish how substance properties depend on their type of bond.
• Investigate the linkage present in ionic and covalent substances through the study of electrical conductivity.

3. Theoretical Foundation

The conductivity of a substance is carried by ions—charged particles formed by one or more atoms—excluding metals, whose electrical conduction is not considered in this experiment.

Ionic compounds do not carry current in the solid state, but they do when dissolved or fused, as their crystal lattice releases...

Solutions and Solubility

Dissolution

Dissolution: Homogeneous is a mixture of two or more substances.

Key Terms

• Solvent: The major component.
• Solute: The minority component.

Solubility Definition

Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a given temperature.

Factors Affecting Solubility

Factors: The solubility depends on the characteristics of the solute and solvent and the temperature of the solution. As a general rule, in the case of the dissolution of a solid into a liquid, the solubility increases as the temperature of the solution increases.

Concentration Measures

Concentration: Indicates the amount of solute dissolved per unit volume of solvent or unit volume of solution:

• Percentage mass concentration

Elemental Properties & Periodic Trends

Metallic Properties in the Periodic Table

Across a Period

Within the same period, the metallic properties of elements increase as one moves to the left and decrease as one moves towards the right.

Down a Group

Within the same group, the metallic properties of elements increase as one moves down the table and decrease as one moves up.

Essential Elements & Their Occurrence

Bioelements: Building Blocks of Life

Primary Bioelements

These are the most abundant elements in living organisms:

• Hydrogen (H)
• Carbon (C)
• Nitrogen (N)
• Oxygen (O)
• Phosphorus (P)
• Sulfur (S)

Indispensable Secondary Bioelements

These are essential for life, required in smaller amounts:

• Sodium (Na)
• Magnesium (Mg)
• Potassium (K)
• Calcium (Ca)
• Manganese (Mn)

Atomic Theory: From Democritus to Quantum Models

Democritus' Atomic Theory

Democritus, in ancient Greece, founded the atomist school. This school, taking a pluralistic approach, proposed that atoms were the fundamental particles. The core principles of atomism are:

1. Atoms move in a vacuum.
2. The shape and size of atoms determine the substance.

Aristotle, conversely, believed that matter was a single, continuous entity.

Dalton's Atomic Theory

John Dalton proposed his atomic theory in the early 19th century. Its key postulates are:

1. Elements are composed of indivisible and indestructible particles called atoms.
2. Atoms of the same element have the same mass and properties.
3. Atoms of different elements have different masses and properties.
4. Chemical compounds are

1. Rutherford Model

The Rutherford model describes the atom as follows:

• The atom possesses a nucleus with a small, positive electric charge that contains almost all the mass of the atom.
• Electrons, which have a negative electric charge, orbit the nucleus at small distances in circular paths.
• The total negative electric charge of the electrons must equal the positive charge of the nucleus, ensuring the atom is electrically neutral.

2. Atomic Spectra

A spectrum is the decomposition of wave radiation into its constituent simple waves. When investigating the energy emitted or absorbed, spectra are classified:

Spectrum Types Based on Emission/Absorption:

• Emission Spectrum: Electromagnetic radiation produced directly by a body. It depends on the nature and

Volumetric Analysis

Requirements for Volumetric Reactions

For a reaction to be used in volumetric analysis, it must meet the following criteria:

• The reaction between the titrant and the titrated substance must be quantitative, without adding excess reagent. The reaction must be complete at the equivalence point.
• The reaction must be fast. If it is slow, it is possible to accelerate it with temperature or catalysts.
• The reaction must be stoichiometric and definite.
• To determine the endpoint, a sensitive method must be available.

Characteristics of a Standard Solution

To prepare a standard solution, there are two methods:

1. Directly dissolve a standard substance and dilute to an exact volume (using a volumetric flask).
2. Prepare a solution of approximate concentration

Atomic Structure Concepts

Balmer Series

The striped visible emission spectrum of H corresponds to the transitions of excited electrons returning to level n = 2.

Lyman Series

If electrons transition to level n = 1, the energy differences are greater, resulting in higher frequencies. The lines of this spectrum appear in the ultraviolet region.

Quantum Model and Orbitals

Quantum Model

An electron with a given energy sublevel occupies a defined region of space called an orbital.

Orbital Definition

An orbital is a region of space where there is a high probability of finding the electron.

Form of an Orbital

The form of an orbital depends on the type of sublevel (q) it belongs to. S orbitals are spherical; P orbitals are dumbbell-shaped (often described as '...

Characteristics of Matter

Matter has mass; that is, when placed on a scale, it creates an imbalance. Matter is impenetrable, as two bodies cannot occupy the same space simultaneously. Matter occupies a space, meaning it has volume. The common component is called matter. Bodies are a limited portion of matter, distinguished by features such as color, texture, smell, etc. Each particular kind of matter is a substance, such as sulfur, cotton, or sugar.

Intensive Properties

Intensive properties do not depend on the amount or form of the substance. Examples include:

• Chemical composition
• Vapor pressure
• Density
• Effusion point
• Fragrance
• Taste

Extensive Properties

Extensive properties directly depend on the amount of substance. Examples include:

• Mass
• Volume
• Smell
• Surface
• Height
• Weight

States