Notes, summaries, assignments, exams, and exercises for Chemistry for Secondary education

Materia: Pure substances: substances that is form by the same kind of particles (molecules, atoms…).  Elements: form by the same kind of atom. We can’t divide them. Ej. P, O, C… Compounds: form by the same kind of molecules. We can divide them. Ej. H₂O, CO₂. Mixtures: substances that is form by different kinds of particles.  Homogeneas: you can’t see the different components. Ej. Seawater. Heterogeneas: you can see the different components. Ej. Granite.
1. The atom: is the smallest unit of a chemical element that retains its identity and properties that can not be divided by chemical processes.Types: Proton: have a positive charge. Neutron: don’t have charge. Electron: have negative charge.
4. Rutherford’s atomic model:
Rutherford...

Atomic Structure Fundamentals

What Are Electrons?

Electrons are negatively charged particles found in all atoms and charged particles.

Thomson's Atomic Model

According to Thomson, the atom was a mass of positive charge with embedded electrons. The negatively charged electrons were distributed within this positive charge to ensure the atom was neutral.

Rutherford's Atomic Model

In Rutherford's model, the atom is formed by a very small nucleus and an electron cloud (cortex). In the nucleus, all its positive charge and almost all its mass are concentrated. In the electron cloud, electrons orbit the nucleus.

Bohr's Atomic Model

The Danish scientist Niels Bohr conducted a series of studies and concluded that electrons orbit the nucleus in specific, quantized...

The Electrical Nature of Matter

Thales of Miletus observed that rubbing amber with a cloth caused both to attract other particles. Benjamin Franklin later suggested that all bodies possess electricity, which can be transferred between them. The three primary methods of electrification are friction, contact, and induction.

The amount of electric charge (Q) is a physical quantity, measured in Coulombs (C). There are two types of electric charge: negative (as found in amber or plastic) and positive (as found in glass). Neutral bodies possess an equal number of positive and negative charges.

Coulomb's Law

Coulomb's Law quantitatively calculates the electric force using the following formula:

F = k * Q1 * Q2 / r²

Where:

• F: Force
• k: Constant of the medium
• Q1

Chromatography
It is a technique based on the different speeds with which each component of a liquid sample can spread through a porous surface, through which the solvent rises by capillary action.
7 Pure Substances: Elements and Compounds
A pure substance that can become simpler substances through transformations is called a compound.
A pure substance that cannot be decomposed into simpler ones is called an element.
A compound is a mixture.
The joining of two or more elements to form a compound is a different process than a mixture.
The constituents of a mixture can be in any proportion and maintain their characteristic properties.
The constituents of a compound are always in the same proportion, and the final substance is a new substance with...

Fundamental Properties of Elements

Classification of Elements

Metallic Properties

• Conductivity: Excellent conductors of heat and electricity.
• Physical State: Solid at room temperature, except for mercury (Hg), which is liquid.
• Ions: Tend to lose electrons, forming positive ions (cations).
• Other Characteristics: Approximately 75% of all elements are metals. They possess metallic luster and are ductile.

Nonmetallic Properties

• Conductivity: Poor conductors of heat and electricity.
• Physical State: Can be solid (e.g., Carbon, Sulfur), liquid (e.g., Bromine), or gas (e.g., Oxygen, Nitrogen) at room temperature.
• Ions: Tend to gain electrons, forming negative ions (anions).
• Other Characteristics: Most nonmetal solids are soft.

Noble Gases

• Physical State: Gases

Understanding Electrification Phenomena

When rubbing certain materials, two electrical phenomena can be observed: attraction or repulsion. Charles inferred the existence of these two classes of electrical phenomena.

Electrification by Contact

This occurs when an isolated, uncharged body comes into contact with another body already charged by friction. To study this, we utilize an electric pendulum. These experiments show that bodies which have come into contact with other previously electrified bodies also become electrified.

Electrification by Induction

To electrify a body, it is not essential for the charged body to make direct contact with the body you wish to electrify (they can be closer but not touching).

Electric Charge: Definition and Properties

Electric

Substantive Clauses and Noun Phrases

A substantive clause is equivalent to a noun phrase or a personal pronoun. These are often relative pronouns without an antecedent. In most positions, they perform common functions, typically involving a subject and a verb in the infinitive form. They are related to verbs that admit personal complements.

Classification of Interrogative Propositions

These propositions belong to the indirect interrogative classification and are divided into total or partial categories:

• Total: These only support a "yes" or "no" answer.
• Partial: These support a range of possible answers.

Substantive functions mirror those of a nominal phrase, such as subject, attribute, direct object (CD), noun complement (CN), adjective complement

Polyatomic Ions

NH₄⁺ – ammonium
CrO₄²⁻ – chromate
ClO₂⁻ – chlorite
C₂H₃O₂⁻ – acetate
Cr₂O₇²⁻ – dichromate
ClO⁻ – hypochlorite
CN⁻ – cyanide
MnO₄⁻ – permanganate
ClO₃⁻ – chlorate
CO₃²⁻ – carbonate
NO₂⁻ – nitrite
ClO₄⁻ – perchlorate
HCO₃⁻ – bicarbonate
NO₃⁻ – nitrate
PO₄³⁻ – phosphate
C₂O₄²⁻ – oxalate
OH⁻ – hydroxide
SO₃²⁻ – sulfite
SO₄²⁻ – sulfate
S₂O₃²⁻ – thiosulfate

The Four Fundamental States of Matter

• Solid: Characterized by structural rigidity and resistance to changes of shape or volume.
• Liquid: A form of matter between a gas and a solid that has a definite volume but no definite shape.
• Gas: An air-like fluid substance which expands freely to fill any space available, irrespective of its quantity.
• Plasma: A state of matter made from a gas that has lost its electrons due to heat (e.g., the Sun, stars, lightning).

Particle Arrangement

• Solid: Particles are tightly packed, usually in a regular pattern. Solids vibrate (jiggle) but generally do not move from place to place.
• Liquid: Particles are close together with no regular arrangement. They vibrate, move about, and slide past each other.
• Gas: Particles are well-

Planetary Model of the Atom

An atom has a very small central region, the nucleus, made up of protons and neutrons. The nucleus is surrounded by a cloud of orbiting electrons. The number of electrons in an atom is equal to the number of protons in its nucleus (atoms have no overall electric charge).

Atomic Number (Z)

The atomic number (Z) of an atom is the number of protons it contains. All the atoms of a particular element have the same atomic number. The atoms of different elements have different numbers of protons.

Mass Number (A)

The mass number (A) of an atom is the total number of protons and neutrons it contains. The full chemical symbol for an element shows its mass number at the top and its atomic number at the bottom.

Ions

• Ion: When an atom