Grade 11
  1. Basic concepts of chemistry  1.1. Importance of Chemistry  1.2. Nature and scope of chemistry  1.3. laws of chemical combination  1.3.1. Law of conservation of mass  1.3.2. Law of definite proportions  1.3.3. Law of multiple proportions  1.3.4. Law of gaseous volume  1.3.5. Avogadro's Law  1.4. Dalton's atomic theory  1.5. Mole concept and molar mass  1.6. Percent composition  1.7. Empirical and molecular formula  1.8. Stoichiometry and Stoichiometric Calculations  1.9. Limiting reagent concept
  2. Structure of the atom  2.1. Discovery of the electron, proton, and neutron  2.2. Atomic Model  2.2.1. Thomson's model  2.2.2. Rutherford's model  2.2.3. Bohr's model  2.3. Quantum mechanical model of the atom  2.4. Dual nature of matter and radiation  2.5. Heisenberg's uncertainty principle  2.6. Quantum numbers  2.7. Atomic orbitals and their shapes  2.8. Electronic configuration of elements  2.9. Aufbau principle  2.10. Pauli's exclusion principle  2.11. Hund's maximum multiplicity rule  2.12. de Broglie's hypothesis  2.13. Photoelectric effect
  3. Classification of elements and periodicity in properties  3.1. Historical development of the periodic table  3.2. Modern Periodic Law and Periodic Table  3.3. Periodic trends in properties  3.3.1. Atomic and Ionic Radius  3.3.2. Ionization enthalpy  3.3.3. Electron gain enthalpy  3.3.4. Electronegativity  3.3.5. Valency  3.3.6. Metallic and Non-Metallic Properties  3.3.7. Oxidation states  3.4. Unusual Properties of the First Elements
  4. Chemical Bonding and Molecular Structure  4.1. Kossel–Lewis approach to chemical bonding  4.2. Ionic or electrovalent bond  4.3. Covalent bond and its features  4.4. Bond parameters  4.5. VSEPR Theory  4.6. Valence bond theory  4.7. Hybridization and its types  4.8. Molecular orbital theory  4.8.1. Bond order and stability  4.9. Hydrogen bonding
  5. States of matter  5.1. Intermolecular forces  5.2. Gas Laws  5.2.1. Boyle's law  5.2.2. Charles's Law  5.2.3. Avogadro's Law  5.2.4. Dalton's law of partial pressure  5.2.5. Graham's law of spread  5.3. Ideal Gas Equation and Applications  5.4. Real gases and deviations from ideal behaviour  5.5. Kinetic molecular theory of gases  5.6. Liquefaction of gases  5.7. Properties of Liquids  5.8. Surface tension and viscosity
  6. Thermodynamics  6.1. System and environment  6.2. Types of systems in thermodynamics  6.3. Types of procedures  6.4. First law of thermodynamics  6.5. Internal energy and enthalpy  6.6. Heat capacity and specific heat  6.7. Hess's law of constant heat summation  6.8. Bond dissociation enthalpy  6.9. Enthalpy of formation and combustion  6.10. Enthalpy of solution and neutralization  6.11. Spontaneity and the second law of thermodynamics  6.12. Gibbs free energy and its applications
  7. Balance  7.1. The concept of balance  7.2. Equilibrium constant and its applications  7.3. Le Chatelier's principle  7.4. Ionic equilibrium in solutions  7.5. Acid and Base Theory  7.5.1. Arrhenius concept  7.5.2. Bronsted-Lowry concept  7.5.3. Lewis concept  7.6. pH Scale and pOH  7.7. Common ion effect  7.8. Hydrolysis of salts  7.9. Buffer solutions and their mechanism of action  7.10. Solubility equilibrium of sparingly soluble salts
  8. Redox reactions  8.1. Oxidation and reduction concepts  8.2. Oxidation number and its applications  8.3. Redox reactions in terms of electron transfer  8.4. Balancing redox reactions (oxidation number and ion-electron methods)  8.5. Types of redox reactions  8.6. Electrochemical Cells and Redox Reactions
  9. Hydrogen  9.1. Position of Hydrogen in the Periodic Table  9.2. Isotopes of hydrogen  9.3. Preparation of Hydrogen  9.4. Properties of Hydrogen  9.5. Hydrides and their classification  9.6. Water and heavy water  9.7. Hydrogen peroxide and its properties  9.8. Uses of Hydrogen and Its Compounds
  10. S-block elements (alkali and alkaline earth metals)  10.1. Group 1 Elements - Properties and Trends  10.2. Group 2 Elements - Properties and Trends  10.3. Unusual properties of lithium and beryllium  10.4. Important compounds of sodium and their uses  10.5. Important Compounds of Magnesium and Calcium
  11. Some p-block elements  11.1. General Introduction to p-Block Elements  11.2. Group 13 Elements  11.2.1. Boron and its compounds  11.3. Group 14 Elements  11.3.1. Carbon and its allotropes  11.3.2. Important Compounds of Carbon and Silicon
  12. Organic Chemistry - Some Basic Principles and Techniques  12.1. Classification and Nomenclature of Organic Compounds  12.2. Structural representation of organic compounds  12.3. Classification of organic reactions  12.4. Electronic Effects in Organic Chemistry  12.4.1. Inductive effect  12.4.2. Resonance effect  12.4.3. Hyperconjugation  12.5. Reaction mechanism and intermediate species  12.6. Purification and qualitative analysis of organic compounds
  13. Hydrocarbons  13.1. Hydrocarbons  13.1.1. Preparation and Properties of Alkenes  13.2. alkene  13.2.1. Preparation and Properties of Alkenes  13.2.2. Electrophilic addition reactions  13.3. Alkynes  13.3.1. Preparation and Properties of Alkynes  13.4. Aromatic hydrocarbons  13.4.1. Structure and properties of benzene  13.4.2. Electrophilic substitution reactions of benzene
  14. Environmental Chemistry  14.1. Environmental Pollution  14.2. Atmospheric pollution and the greenhouse effect  14.3. Water pollution and treatment methods  14.4. Soil pollution and its effects  14.5. Industrial waste and its treatment  14.6. Strategies for pollution control

Grade 11 → S-block elements (alkali and alkaline earth metals) ↓


Group 1 Elements - Properties and Trends


Group 1 elements, also known as alkali metals, are a fascinating group of elements with unique and distinctive properties. These elements are located in the first column of the periodic table and include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). This group is characterized by the single electron present in its outermost shell, which is responsible for its chemical behavior. In this discussion, we will delve deeper into the properties and observable trends of these elements as we move down the group.

1. General properties of group 1 elements

Chemical reactivity

One of the most notable properties of the alkali metals is their high reactivity. This reactivity is due to their low ionization energy, which makes it easy for them to lose their outermost electron and form a positive ion. The general reaction for an alkali metal reacting with water can be written as:

2M + 2H 2 O → 2MOH + H 2

Where M represents group 1 metal.

Softness

The alkali metals are known for their softness. They have a metallic luster, but they are usually soft enough to be cut with a knife. The metals get softer as you move down the group from lithium to cesium.

Low melting and boiling point

Metals in group 1 have relatively low melting and boiling points compared to other metals. These points decrease as we go down the group. For example:

  • The melting point of lithium is about 180.5°C.
  • Sodium melts at 98°C.
  • Potassium melts at 63.5°C.

2. Physical properties and atomic structure

Atomic and ionic radius

The atomic and ionic radii of group 1 elements increase as we move down the group. This is due to the addition of electron shells in each successive element. Even though the nuclear charge increases, the addition of a new shell negates this effect, making the atomic size larger. This can be visualised as follows:

[Li] 2s 1 < [Na] 3s 1 < [K] 4s 1 < [Rb] 5s 1

Density

The alkali metals are generally lower in density than the other metals, with lithium, sodium and potassium all having densities less than water, allowing them to float. Density increases as atomic number increases, except for potassium, which has a lower density than sodium.

Appearance

These metals are shiny and silvery but tarnish quickly when exposed to air due to the formation of an oxide layer on the surface.

3. Trends in chemical properties

Ionization energy

The ionization energy of alkali metals decreases as we go down the group. This is because the outer electron is far from the nucleus and is completely shielded by the inner shells, making it easier to remove.

Reactivity with water

The reactivity of Group 1 elements with water increases going down the group. Lithium reacts slowly, forming lithium hydroxide and hydrogen gas, while sodium reacts more vigorously, and potassium even more aggressively, often igniting the hydrogen gas produced.

Reactivity with air

All alkali metals react with oxygen to form oxides, although the nature of oxidation varies. Lithium forms lithium oxide (Li 2 O), sodium forms sodium peroxide (Na 2 O 2), and potassium forms potassium superoxide (KO 2) as their major products.

4. Common compounds and their applications

The alkali metals form a wide variety of compounds that have important industrial and practical uses. Some common compounds include:

  • Sodium chloride (NaCl): Also known as table salt, this compound is essential to the human diet and has numerous industrial uses.
  • Lithium carbonate (Li 2 CO 3): It is used in the treatment of bipolar disorder and is also a key component of rechargeable lithium-ion batteries.
  • Potassium hydroxide (KOH): Used in the manufacture of soap and as a precursor to other potassium compounds.

5. Observing the effects of group 1

To see more clearly the trends and properties of the alkali metals down the group, consider the following schematic representation:

Took No K

This diagram shows the simplified increase in atomic and ionic sizes as we move up the group from lithium to potassium. An increase in size leads to greater reactivity and lower ionization energies.

6. Safety and precautionary measures

Due to their high reactivity, especially with water and moisture in the air, careful handling of the alkali metals is necessary. They are often stored under oil to prevent unwanted reactions. Proper safety equipment such as goggles, gloves, and face shields should be used when handling these metals in a laboratory setting.

7. Conclusions

The study of the group 1 elements reveals a pattern of properties and behaviours determined by their electronic configuration. As we move from lithium to francium, the trends observed are directly related to changes in size, energy levels and electron interactions. This makes the alkali metals particularly important subjects of study in the fields of chemistry and physics, with their application reaching a variety of technological and industrial areas.

Understanding these properties not only helps in predicting their behaviour, but also in developing new materials and solutions to modern scientific and industrial challenges.


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Group 1 Elements - Properties and Trends

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