Hydrocarbon Classification and Properties

Chemical Categories

• Aliphatic: Chains/rings (Alkanes, Alkenes, Alkynes).
• Aromatic: Contains benzene ring.
• Derivatives: Organic. Atoms like O, N, halogens replace H.
• Inorganic: Oxides (CO₂, CO), Carbonates (CaCO₃, NaHCO₃), Carbides (CaC₂, SiC), Cyanides (NaCN).

Functional Groups

• Carboxylic Acid (-oic acid)

Acid-Base Equilibrium Practice Problems

1. The conjugate acid of HAsO₄²⁻ is:
   Answer: C. H₂AsO₄⁻
2. Which of the following tests could be used to distinguish between 1.0 M HCl and 1.0 M NaOH?
   Answer: C. II and III only
3. Consider the following Brønsted-Lowry equilibrium:
   C₆H₅NH₂(aq) + H₂O(l) ⇌ C₆H₅NH₃⁺(aq) + OH⁻(aq)
   The substances acting as acids and bases from left to right are:
   Answer: C. Base, acid, acid, base
4. Which of the following are amphiprotic?
   I. H₂O, II. NH₄⁺, III. HCO₃⁻
   Answer: B. I and III only
5. Which of the following represents the equilibrium expression for the ionization of water?
   Answer: A.
6. Which of the following will have the lowest electrical conductivity?
   Answer: D. 1.00 M H₃PO₄
7. Water acts as an acid when

Atomic Structure and Properties

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Outer Shells of Atoms

• 2 electrons
• 8 electrons
• 8 electrons

Key Definitions

• Isotopes: Atoms of a single element that have a different number of neutrons.
• Valency: The capacity of an atom to give, accept, or share electrons to achieve the octet state.

Ionic Bonding

Formation of Ions

Ions are formed when neutral atoms or molecules gain or lose electrons to achieve a stable, full outer shell. An ion is an atom that has lost or gained an electron.

• If an atom has lost an electron, it becomes a positive ion.
• If an atom has gained an electron, it becomes a negative ion.

Ionic Bonds

An ionic bond is the electrostatic attraction between a positively charged metal ion (cation) and a negatively charged non-metal ion (anion). Opposite...

🔹 Isomerism (Class 11)

Definition:

Isomers are compounds having the same molecular formula but a different arrangement of atoms or different spatial arrangement, resulting in different properties.

1️⃣ Structural Isomerism

(Atoms have a different connection)

(A) Chain Isomerism

Definition:

Same molecular formula but a different carbon chain (straight or branched).

Example:

• C₄H₁₀
  • n-Butane → CH₃–CH₂–CH₂–CH₃
  • Isobutane → CH₃–CH(CH₃)–CH₃
• C₅H₁₂
  • Pentane
  • Isopentane
  • Neopentane

(B) Position Isomerism

Definition:

Same carbon chain and functional group, but the position of the functional group or multiple bond is different.

Example:

• C₃H₈O
  • 1-Propanol (–OH on C-1)
  • 2-Propanol (–OH on C-2)
• C₄H₈
  • 1-Butene
  • 2-Butene

(C) Functional

Fundamental Concepts in Atomic Structure and Quantum Theory

1. Electron: Properties and Discovery

A negatively charged subatomic particle discovered by J.J. Thomson using cathode ray experiments. It is found outside the nucleus and possesses negligible mass.

2. Proton: Location and Atomic Number

A positively charged particle discovered by Goldstein. It is located inside the nucleus and uniquely defines the atomic number of an element.

3. Neutron: Mass Contribution and Discovery

A neutral subatomic particle discovered by James Chadwick. It resides in the nucleus and contributes significantly to the mass of the atom.

4. Atomic Number (Z): Definition and Identity

The number of protons found in the nucleus of an atom. It uniquely identifies the chemical...

1. What Is Static Electricity?

Static electricity is the imbalance of electric charge accumulated on an object’s surface.

It is commonly observed in daily life, resulting in phenomena such as:

• Hair rising
• A balloon sticking to a wall

2. Atomic Structure and Electric Charge

Electric charge is determined by the components of the atom:

• Proton: Positive (+) charge (located in the nucleus)
• Neutron: Neutral (0) charge (located in the nucleus)
• Electron: Negative (–) charge (orbits the nucleus)

Charge states are defined by the balance of protons and electrons:

• Neutral Atom: Equal number of protons and electrons
• Positive Charge: More protons than electrons (net loss of electrons)
• Negative Charge: More electrons than protons (net gain of electrons)

3. Methods

Hazard Symbols

Hazard symbols explain why a substance must be handled carefully.

Air Pollution from Burning Fossil Fuels

Complete combustion - the fuel reacts completely with oxygen, e.g.:

hydrocarbon + oxygen → carbon dioxide + water

Incomplete combustion - the fuel only partly reacts with oxygen, e.g.:

hydrocarbon + oxygen → carbon dioxide + water + carbon monoxide + carbon (soot)

Impurities in fossil fuels, such as sulfur, also react with oxygen when heated:

sulfur + oxygen → sulfur dioxide

At the very high temperatures in vehicle engines, nitrogen gas from the air reacts with oxygen:

nitrogen + oxygen → nitrogen oxides

Many products from burning fossil fuels are pollutants; they harm habitats and their organisms.

Acid Rain

Acid rain is rainwater...

Dalton's Atomic Theory

John Dalton proposed that elements were made up of little solid spheres without internal structure. Atoms of the same element were equal. Atoms combine, forming compounds. Depending on the ratio, we can have different compounds.

J.J. Thomson

First model of the atom (1904). He discovered/proved the existence of tiny, negatively charged particles: electrons.

Rutherford's Model of the Atom

Gold foil experiment, Ernest Rutherford (1911). Alpha particles are tiny, positively charged particles much smaller than an atom. An atom is mostly empty space. Some particles will bounce back, and some others will pass but in a different way. The nucleus is something dense and positively charged.

Thomson's Atomic Model

In 1904, Thomson's atomic...

Understanding Metallic Bonds

A metallic bond is a type of chemical bond where the electrostatic attraction between positive metal ions (kernels) and delocalized electrons holds the metal ions in their respective positions. In metal atoms, the valence electrons are loosely bound and are free to move from one atom to another within the metallic crystal lattice. These free electrons, also known as conduction electrons or delocalized electrons, are uniformly distributed throughout the metal lattice.

When metal atoms lose these conduction electrons, they become positive ions, or kernels (atoms without their valence electrons). The electrostatic (or coulombic) interaction that develops between these positive kernels and the sea of negative electrons...

Physical and Chemical Changes

Physical changes do not cause new substances to appear. However, chemical changes produce substances that were not present before the transformation, as a result of a chemical change.

Reagents and Products in a Chemical Reaction

Reagents are the pure substances that are combined together in order to produce a chemical reaction. Products are the substances produced as a result of combining reagents in order to produce a chemical reaction.

Characteristics of Chemical Changes

• Energy is exchanged throughout the course of a chemical reaction.
• Reversible and irreversible reactions.
• The states of aggregation.

Collision Theory in Chemical Reactions

According to collision theory, chemical reactions take place because the molecules...