Grade 8
  1. Introduction to Chemistry  1.1. Nature and scope of chemistry  1.2. Importance of chemistry in daily life  1.3. Chemistry and its relation with other sciences  1.4. The role of chemistry in industry, medicine and the environment  1.5. Scientific investigation and experimental methods in chemistry
  2. Matter and its properties  2.1. Definition and classification of matter  2.2. Physical and chemical properties of matter  2.3. Law of conservation of matter  2.4. Extensive and Intensive Properties of Matter  2.5. Kinetic molecular theory of matter  2.6. States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates  2.7. Changes in state and energy are involved  2.8. Diffusion and Brownian motion
  3. Elements, Compounds, and Mixtures  3.1. Definition and differences between elements, compounds, and mixtures  3.2. Atomic Structure and Atomic Number  3.3. Chemical symbols and formulas  3.4. Trends in the Periodic Table (Groups and Periods)  3.5. Classification of Elements: Metals, Nonmetals and Metalloids  3.6. Rare Earth Elements and Transition Metals  3.7. Types of mixtures: homogeneous and heterogeneous  3.8. Separation of Mixtures Using Physical and Chemical Methods
  4. Separation Techniques  4.1. Filtration, Sedimentation and Decantation  4.2. Evaporation and crystallization  4.3. Distillation and Fractional Distillation  4.4. Chromatography and its applications  4.5. Sublimation in the purification of compounds  4.6. The role of centrifugation in biochemical processes
  5. Atomic Structure  5.1. Dalton's atomic theory  5.2. Structure of the atom: protons, neutrons and electrons  5.3. Bohr's atomic model  5.4. Introduction to Quantum Mechanical Model  5.5. Electron Configuration and Energy Levels  5.6. Excitation and emission spectra  5.7. Isotopes and their applications
  6. Periodic Table and Chemical Trends  6.1. History and Development of the Periodic Table  6.2. Modern periodic law  6.3. Periodicity and trends in atomic and ionic sizes  6.4. Ionization Energy, Electron Affinity and Electronegativity  6.5. Introduction to Lanthanides and Actinides  6.6. Application of periodic trends in chemistry
  7. Chemical Bonding and Molecular Structure  7.1. Types of chemical bonds: ionic, covalent and metallic bonds  7.3. Polar and Nonpolar Molecules  7.4. Hydrogen bonding and its applications  7.5. Intermolecular forces: dipole-dipole, London dispersion force
  8. Chemical Reactions and Stoichiometry  8.1. Chemical Equations and Balance  8.2. Types of Chemical Reactions: Combination, Decomposition, Displacement and Redox  8.3. Introduction to stoichiometry and the mole concept  8.4. Limiting reactant in chemical equations  8.5. Reaction rate, catalyst, and factors affecting reaction rate
  9. Acids, Bases and Salts  9.1. Definition and Properties of Acids and Bases  9.2. Strong vs. Weak Acids and Bases  9.3. pH Scale and pH Calculation  9.4. Neutralization reactions  9.5. Buffer solutions and their importance  9.6. Applications of Acids, Bases and Salts in Daily Life
  10. Solutions and Solubility  10.1. Definition of Solution, Solute, and Solvent  10.2. Factors Affecting Solubility  10.3. Concentration units: molarity and molality  10.4. Saturated, unsaturated and supersaturated solutions  10.5. Concept of osmosis and reverse osmosis  10.6. Concentrative properties of solutions
  11. Gases and Gas Laws  11.1. Properties of gases  11.2. Introduction to Ideal and Real Gases  11.3. Boyle's Law, Charles' Law and Avogadro's Law  11.4. Ideal Gas Equation and Its Applications  11.5. Application of Gas Laws in Real Life
  12. Thermochemistry and energy transformation  12.1. Energy in Chemical Reactions  12.2. Exothermic vs. Endothermic Reactions  12.3. Heat and Enthalpy Changes  12.4. Calorimetry and heat transfer in reactions
  13. Metals and Nonmetals  13.1. Physical and Chemical Properties of Metals and Nonmetals  13.2. Reactivity Series of Metals  13.3. Corrosion and its prevention  13.4. Extraction of metals from ores  13.5. Uses of metals and non-metals in daily life
  14. Introduction to Organic Chemistry  14.1. Characteristics of carbon and organic compounds  14.2. Functional groups and their importance  14.3. Simple Hydrocarbons: Alkenes, Alkenes and Alkynes  14.4. Isomerism in organic compounds  14.5. Introduction to polymers and their uses
  15. Environmental Chemistry and Sustainability  15.1. Green Chemistry Principles  15.2. Effects of Chemical Pollution on Ecosystems  15.3. Acid rain and its effects  15.4. Ozone layer depletion and global warming  15.5. Waste Management and Recycling in Chemistry

Grade 8 ↓


Periodic Table and Chemical Trends


The periodic table is a systematic organization of the chemical elements based on their properties. Each element has a unique atomic number, which is the number of protons in its nucleus. The elements are arranged in rows called periods and columns called groups or families.

Understanding the periodic table helps us predict how elements will interact with one another, and it provides information about the properties of the elements. The periodic table is an important tool in the field of chemistry.

Structure of the Periodic Table

The periodic table is arranged in rows and columns:

  • Horizontal rows in the periodic table. There are seven periods in the table. Elements in the same period have the same number of atomic orbitals.
  • Group: Vertical column in the periodic table. There are 18 groups in the table. Elements in the same group often have similar chemical properties because they have the same number of valence electrons.

Sections of the Periodic Table

The periodic table can be divided into several parts:

  • Metals: Located on the left and in the middle of the table. Metals are usually shiny, good conductors of heat and electricity, and malleable.
  • Nonmetals: Found on the right side of the periodic table. Nonmetals are dull, poor conductors of heat and electricity, and are brittle in solid form.
  • Metalloids: Found along the zigzag line (ladder) that separates metals from nonmetals. Properties of metalloids are intermediate between those of metals and nonmetals.

Groups and their characteristics

Let us discuss some specific groups and their characteristics:

Group 1: Alkali Metals

The alkali metals include lithium (Li), sodium (Na), and potassium (K). They are highly reactive, especially with water, and have one valence electron.

Group 2: Alkaline Earth Metals

This group includes beryllium (Be), magnesium (Mg), and calcium (Ca). They are somewhat reactive metals with two valence electrons.

Group 17: The Halogens

The halogens include fluorine (F), chlorine (Cl), and iodine (I). These nonmetals have seven valence electrons and are highly reactive.

Group 18: Noble gases

The noble gases include helium (He), neon (Ne), and argon (Ar). They are non-reactive due to having a full valence shell.

Visual Example: Periodic Table Simplification

Periods: Horizontal rows Groups: Vertical columns Section: Metals | Nonmetals ------------------ Metalloids

Chemical Trends in the Periodic Table

Chemical trends refer to specific patterns that appear in the properties of elements as we move across the periodic table.

Atomic radius

The atomic radius is the distance from the nucleus to the outermost electrons.

  • The atomic radius decreases from left to right across a period because the number of protons that attract the electrons near the nucleus increases.
  • The atomic radius increases as we go down a group, because each element has an extra electron shell compared to the one above it.

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom.

  • The ionization energy increases across a period as the nuclear charge increases, making it more difficult to remove an electron.
  • Ionization energy decreases as we go down the group, because the electrons are farther from the nucleus and experience more shielding.

Electronegativity

Electronegativity describes how strongly an atom can attract electrons towards itself.

  • Due to increase in nuclear charge, electronegativities increase across a period.
  • Electronegativity decreases going down the group because the extra electrons reduce the shell attraction.

Illustration of chemical trends

Electronegative / Ionization Energy / | | Group 18 | o Ar | Noble Gases ------------- ---------------------------- | | Group 1 | o Li | Alkali Metals | |

Blocks of the Periodic Table

The periodic table is divided into blocks that correspond to the electron sublevels being filled:

  • s-block: It includes groups 1 and 2 and helium. It involves the filling of s orbitals.
  • p-block: It includes groups 13 to 18. It involves the filling of p orbitals.
  • d-block: Covers groups 3 to 12, extends into the transition metals. Involves d orbitals.
  • f-block: It includes the lanthanides and actinides. It includes f orbitals located below the main body of the table.

Understanding Electronic Configuration

The electronic configuration describes the distribution of electrons in the orbitals of an atom. For example, the electronic configuration of sodium (Na) is:

1s² 2s² 2p⁶ 3s¹

This notation shows how electrons fill the lowest energy orbitals first, following the Aufbau principle, the Hund rule, and the Pauli exclusion principle.

Conclusion

The periodic table is a powerful tool that helps chemists understand the properties and behaviors of elements. Its organization reveals chemical trends that help predict how different elements will interact. By studying the table, one gains information about atomic structure that shapes our understanding of chemistry. It is essential to understand these basic concepts early on because they lay the groundwork for more advanced studies in chemistry.


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Periodic Table and Chemical Trends

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