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

The Thomson Atomic Model

The Thomson Model was based on the discovery of the electron as a particle of very small mass and negative charge; he proposed that all atoms have electrons. But as the atom is neutral, the rest of the "dough" should be positive. When the protons were discovered, they were found to have the same charge as the electron but positive, and they had the same mass as hydrogen (though this was later corrected).

Rutherford's Nuclear Atom

The Nuclear or Rutherford atom experimentally found that in almost all atoms, the mass is located in a central area called the core or nucleus. This is where the positive charges of the atom (protons) are located, while electrons are encountered orbiting outside the nucleus in circular orbits....

Sieving: Separating Solid Particles by Size

Sieving is a physical method used for separating heterogeneous solid mixtures. It involves passing a mixture of solid particles of different sizes through a sieve or colander. The smaller particles pass through the pores, while larger particles are retained by the screen.

This is a very simple method generally used for solid heterogeneous mixtures, such as separating sand (which passes through the sieve) from stones (which are retained). The screen openings are usually of different sizes and are selected according to the size of the particles in the mixture.

Application of Screening

To apply this method, it is necessary that both phases are present in the solid state. Metal or plastic sieves are used,...

The Definition of a Word

The most rigorous definition of a word, which avoids controversy, is that it is the sequence of characters found between two spaces.

Structures of Words

Words are composed of monemes, which are the smallest linguistic units equipped with significance.

• Lexeme: Contains the core meaning of the word.
• Morphemes: Contain the grammatical meaning of the word.

Classes of Morphemes

• Linked or Dependent: Bound to other elements of the word.
• Free or Independent: Can stand alone as a word.

Classification by Meaning

• Derived Morphemes (Affixes): Used to form new words from a lexeme or word base.
• Flexive Morphemes: Located at the end of the word; also known as grammatical accidents.

Morphological Analysis

The objective of morphological analysis...

Essential Bioelements in Living Organisms

Bioelements are chemical elements that constitute biomolecules. The majority have incomplete external electronic layers and a lower atomic number, allowing them to be easily incorporated into living organisms.

Classification of Bioelements

• Primary Bioelements: These majority elements constitute 99% of living matter and include C, H, O, N, P, and S.
• Secondary Bioelements: Found in all living things, but to a lesser extent, these include Na, K, Ca, Mg, and Cl.
• Trace Elements: Present in proportions below 0.1%, these are equally essential. Some, such as Fe, Cu, Zn, Mn, I, Ni, and Co, are present in most organisms. Others, like Si, F, Cr, Li, B, Mo, and Al, are found only in specific groups.

Biomolecules: The

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Mendeleev's Periodic Law and Atomic Structure

Item 2.1. Mendeleev's periodic law stated that the properties of chemical elements do not vary arbitrarily but in a systematic manner with their atomic mass.

Principal Merits of Mendeleev's Table

• The periodic table demonstrated the periodic properties of chemical elements.
• It gave absolute priority to chemical properties.
• When the properties of elements did not fit, he did not hesitate to leave gaps in the table.
• He correctly forecast the atomic mass and properties that elements occupying the reserved spots in the table should have.

Moseley's Contribution

Moseley determined the wavelengths of X-rays produced by different elements.

3. Different Energy Levels

• Level: Where electrons have the same principal quantum

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Classification of Elements by Common Oxidation States

The following lists categorize elements based on their typical oxidation states or group characteristics:

• +1 State: H, Li, Na, K, Rb, Cs, Fr, Zn, Ag, F
• +2 State: Be, Mg, Ca, Sr, Ba, Ra, Cd, O
• Variable States:
  • Mn: (+2, +7)
  • Fe, Ni, Co: (+2, +3) (Co assumed from Ci)
  • Cu, Hg: (+1, +2)
  • Pd, Pt, C, Si, Ge, Sn, Pb: (+2, +4)
  • Au: (+1, +3)
• Group 13 (+3 State): B, Al, Ga, In, Tl
• Group 15 (+3, +5 States): N, P, As, Sb, Bi
• Group 16 (-2, +4, +6 States): S, Se, Te, Po
• Group 17 Halogens (+1, +3, +5, +7 States): Cl, Br, I

Fundamental Periodic Trends

Ionization Energy (IE)

The minimum energy required to remove an electron from a gaseous atom in its ground state, forming a positive ion (cation). Trend: Increases moving right...

Nuclear Physics: Types of Radiation

Alpha rays were identified by Rutherford as helium atoms but with two net positive electric charges, i.e., helium nuclei. Beta rays were identified by Becquerel as cathode rays, and he concluded that they were electrons. Their mass is about 8,000 times lower than that of the alpha rays. Gamma rays were identified as electromagnetic radiation, much like X-rays but of higher energy.

Radioactive Displacement Laws

• When a nucleus emits an alpha particle (α), it becomes another nucleus whose mass number is four units lower and its atomic number is two units less.
• When a nucleus emits a beta particle (β), it becomes another nucleus whose mass number is the same and whose atomic number is one greater.
• When a nucleus

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Electron Motion: Bohr Model vs. Quantum Theory

The description of electron motion around the nucleus of an atom differs significantly between the Bohr model and modern quantum theory.

Bohr's Planetary Model

In Bohr's planetary model, the electron's position and velocity can be precisely determined at any given time, allowing for the prediction of its linear motion in a fixed orbit around the nucleus of the atom.

Modern Quantum Theory and Orbitals

Modern quantum theory introduces the concept of an orbital, where the electron in its motion around the nucleus can take any path randomly and therefore does not follow a predetermined trajectory as in a classical orbit. An orbital provides the probability of finding the electron at a certain distance from...

Basic Atomic Structure

• Proton: A particle with a positive charge located in the nucleus. Mass = 1 AMU.
• Neutron: An atomic particle with no charge and a mass approximately equal to a proton. It is a structural component of the atomic nucleus. Mass = 1 AMU.
• Electron: A particle with a negative charge that orbits the nucleus.
• Nucleus: The positively charged center of an atom.
• Atom: The basic unit of a chemical element.
• Atomic Mass Unit (AMU): Used to express atomic and molecular weight.
• Atomic Number: The number of protons in an atom of a chemical element.
• Isotope: Atoms of an element containing an equal number of protons but a different number of neutrons in their nuclei.

Isotopes

• All atoms of an element do not weigh the same amount.
• The number of neutrons

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English Culinary Terms

Preparation and Mixing Methods

• Beat: To use a spoon, fork, whisk, or electric mixer to mix ingredients together, using a fast circular movement (batir).
• Blend: To combine two or more ingredients until the mixture is smooth and uniform in texture, color, and flavor (barrejar).
• Bread: To coat a food in bread crumbs before frying or baking (rebozar).
• Chill: To put food in the refrigerator for at least two hours (refredar).
• Chop: To cut into little pieces (trocear).
• Dice: To cut into small square pieces (cortar a cuadrados).
• Drain: To remove all liquid – may be done in a strainer or by pressing a plate against the food while tilting the container forward (quitar líquido).
• Grate: To scrape against the small holes of a grater, making

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