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

Chemistry: Structure, Composition, and Transformations of Matter

Chemistry is the science that studies the structure, composition, and transformations of matter.

Combustion and Oxidation Reactions

Combustion is a rapid chemical reaction of any substance with oxygen, commonly known as oxidation.

Examples of Combustion Reactions:

• C + O₂ → CO₂
• Fe + O₂ → Fe₂O₃

Chemical Reaction Rate

The reaction rate is defined as the amount of substance reacting per unit time (e.g., per second).

The velocity of the reaction is favored by the following factors:

1. State of Matter: The rate is typically greater for gases, followed by liquids, and then solids.
2. Temperature: Increased temperature causes greater mobility of the particles, accelerating the reaction.
3. Agitation:

The Bohr Atomic Model (1913)

The Bohr model was developed based on studies of atomic emission spectra and quantum theory.

Key Foundations

• Emissions of Atoms: The light emitted by an element is called its spectrum, and each element possesses a unique one.
• Quantum Theory: In a chemical reaction, one cannot refer to a quantity of material less than one atom. Furthermore, there is a minimum amount of energy that can be emitted, known as a photon or quantum.

Bohr's Four Basic Tenets

• Electrons in atoms are located in specific orbits or energy levels around the nucleus.
• Electrons in orbits closer to the nucleus possess lower energy than those in more remote orbits.
• Any electron in an atom can have only certain allowed energy values, which determine its orbit.

Chemical Reactions

Types of Chemical Reactions

• Synthesis: A + B → AB
• Decomposition: AB → A + B
• Single Displacement: A + BC → AC + B
• Double Displacement: AB + CD → AD + CB
• Combustion: A + O₂ → H₂O + CO₂ (typically for hydrocarbons)
• Acid-Base: Acid + Base → Salt + Water
• Precipitation: Soluble Salt A + Soluble Salt B → Precipitate + Soluble Salt C

Stoichiometry and Mole Concepts

Key Stoichiometry Relationships

• Mass: 1 mole = Molar Mass (in grams)
• Volume: 1 mole = 22.4 L @ STP (Standard Temperature and Pressure)
• Particles: 1 mole = 6.022 × 10²³ particles (Avogadro's Number)
• Mole-Mole Conversions: Use coefficients from a balanced chemical equation.

Standard Temperature and Pressure (STP)

• Temperature: 0 °C (273.15 K)
• Pressure: 1 atm

Gas Laws

^{Correction fluid is a white liquid. The organic solvent was originally used as an ingredient in the product. This solvent is readily absorbed by the lungs via inhalation. It has been replaced by a safer alternative for painting over mistakes. A brush (which was later replaced by a foam applicator) is attached to the cap, so when the bottle is closed, the brush is immersed in the fluid. When unscrewed, the brush is covered in liquid which is then painted over the mistake. However, it is still possible to see that the product has been used, and also the original content if the paper is held up to a light.}

Functions of Language

• Expresiva or emotiva: expresses feelings
• Funcion apelativa: incites the receiver
• Representativa: provides information
• Poetica

Electrical Conductivity in Solids

Metal atoms possess outer electrons that are not tied to any single atom. These free electrons can move freely within the metal's structure when an electric current is applied, making metals excellent conductors. In contrast, covalent or ionic solids lack such free electrons, preventing electron flow and making them non-conductors.

Electron Configuration Principles

Filling Electron Shells and Orbitals

To determine electron configuration, first fill all lower electron shells. Then, apply specific rules to place valence electrons into their proper shells. Hund's Rule is crucial: it states that electrons will singly occupy all orbitals within a subshell before any orbital is doubly occupied. The Pauli Exclusion Principle...

To separate crude oil into its fractions, we use fractional distillation. This process occurs in an oil refinery. The crude oil is heated to about 350 degrees Celsius in a column that gets cooler higher up. Each fraction will evaporate and rise up the column until it reaches a part that is cool enough to condense it. The liquid goes into its respective tube and is separated from the rest of the crude oil. The smallest alkanes, which have a lower boiling point, will rise to the top. The largest fraction, bitumen, never evaporates and falls as a liquid to the bottom.

Cracking

Crude oil contains a mix of alkanes. Shorter alkanes are the most useful as fuels. We can obtain more shorter alkanes by breaking down the larger ones. This process is called...

Three major characteristics of life

The cell theory

Three major domains of life

Unit 1: Memory and Experience Vocabulary

Key Vocabulary for Memory and Recollection

• remember: recordar
• recall: traer de la memoria
• record: grabar
• appointments: citas
• diary: diario
• memorize: memorizar
• memory: memoria
• memories: recuerdos
• calendar: calendario
• remind: recordar
• mind: mente
• forget: olvidar
• learn: aprender
• by heart: de memoria

Phrasal Verbs Related to Action and Resolution

• carry out: llevar a cabo
• let something down: decepcionar
• sort out: ordenar/preparar
• work out: resolver

Common False Friends in English

• anxious: nervioso vs. eager: ansioso
• success: éxito vs. event: suceso
• embarrassed: avergonzado vs. pregnant: embarazada

Expressing Feelings and Emotions

Intensity of Feelings: From Mild to Strong

• angry/cross → furious
• upset → heartbroken/devastated
• frightened/

Ionic Bonds: Electron Transfer

Ionic bonds form when electrons are transferred between atoms, resulting in positively charged cations (+) and negatively charged anions (-).

Covalent Bonds: Electron Sharing

Covalent bonds form when atoms share electrons. This can be visualized by connecting the dots in Lewis structures.

Electronegativity Difference (|ΔEneg|) and Bond Type

• 2.1 - 3.3: Ionic
• 1.7 - 2.0: Borderline (use other information, e.g., boiling/melting points)
• 0.4 - 1.6: Polar Covalent
• 0.0 - 0.3: Non-Polar Covalent

Drawing Covalent Bonds (Lewis Structures)

1. Place the least electronegative element (not Hydrogen) in the center. Count the total number of valence electrons for all atoms.
2. Connect other atoms to the central atom with single bonds (one shared

Gas Laws and Constant Variables

Constant Temperature: Boyle's Law

If the temperature remains constant, increasing the pressure on a gas decreases the volume it occupies. This occurs because the number of collisions per unit surface area increases.

Constant Pressure: Charles's Law

If the pressure on a gas is constant, a rise in temperature causes an increase in the volume it occupies. This is due to the particles having higher kinetic energy and therefore moving faster, causing more frequent collisions.

Constant Volume: Gay-Lussac's Law

If the volume occupied by a gas remains constant, an increase in temperature causes an increase in the pressure of the gas. This is because increasing the temperature increases the kinetic energy of the particles,...