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 → Classification of elements and periodicity in properties → Periodic trends in properties ↓


Metallic and Non-Metallic Properties


The periodic table of elements is an important tool in chemistry, providing a framework for understanding the trends and behaviors of different elements. A fundamental aspect of these trends is associated with the metallic and nonmetallic properties of the elements. This subject explores how and why the elements exhibit these characteristics and how they change across periods and groups.

Introduction to metallic properties

Metallic properties refer to characteristics of elements that are typically associated with metals. These properties include:

  • Lustre: Metals are lustrous when cut, polished, or freshly broken.
  • Malleability: Metals can be hammered or rolled into thin sheets.
  • Ductility: Metals can be drawn into wires.
  • Conductivity: Metals are good conductors of heat and electricity.
  • Sound: Sound is produced when metals are struck.

The metallic character of an element depends on its ability to lose electrons to form positive ions, called cations. It is characteristic of elements with fewer valence electrons and lower ionization energy.

Introduction to nonmetallic properties

Non-metallic properties, on the other hand, are associated with elements that are generally classified as non-metals. These properties include:

  • Poor Conductivity: Nonmetals are generally poor conductors of heat and electricity.
  • High Ionization Energy: Nonmetals have high ionization energy as compared to metals.
  • High electronegativities: Nonmetals have a high ability to attract electrons towards themselves.
  • Brittleness: Nonmetals are brittle in the solid form.

The nonmetallic property is associated with the ability of an element to gain electrons and form negative ions, called anions. This is typical for elements with more valence electrons and higher ionization energy.

Periodic trends in metallic and non-metallic properties

Trends over a period

As we move along a period from left to right in the Periodic Table, there are several changes in the properties of elements:

  • The metallic character decreases.
  • Non-metallic properties increase.

This can be explained by the following trends over a period:

  • Decrease in atomic radius: As we move across a period, protons and electrons get added which increases the nuclear charge. However, the increase in nuclear charge pulls the electrons closer to the nucleus, which decreases the atomic radius.
  • Increase in ionization energy: With smaller atomic radius, the attraction between the nucleus and the outer electrons is stronger, making it harder to remove an electron. Thus, the ionization energy increases.
  • Increase in electronegativities: Due to increase in nuclear charge, the ability of the atom to attract electrons increases, thereby increasing electronegativities.

As a result, elements located on the left side of the period (e.g., alkali and alkaline earth metals) are generally metallic, whereas elements located on the right side of the period (e.g., halogens and noble gases) are nonmetallic.

Downward trend in the group

While going down a group in the periodic table, the elements show the following trends:

  • Metallic properties increase.
  • The non-metallic character decreases.

There may be the following reasons for this:

  • Increase in atomic radius: As we move down the group, new electron shells are added, which increases the atomic radius.
  • Decrease in Ionization Energy: With the addition of more electron shells, the outer electrons move away from the nucleus, weakening the nuclear attraction and thus decreasing the ionization energy.
  • Decreasing electronegativities: The tendency of atoms to attract electrons decreases with increase in atomic size and the distance between the nucleus and the outer electrons.

Therefore, the elements at the bottom of a group, such as the alkali metals and alkaline earth metals, are more metallic than the elements at the top.

Visual representation of trends

During a period

<svg width="600" height="200"> <line x1="10" y1="100" x2="590" y2="100" stroke="black" /> <line x1="10" y1="100" x2="10" y2="20" stroke="black" /> <text x="15" y="30">Non-metallic character</text> <line x1="10" y1="100" x2="10" y2="180" stroke="black" /> <text x="15" y="170">Metallic character</text> <polygon points="10,160 50,140 90,110 130,60 170,40 210,30 250,20 290,30 330,40 370,60 410,90 450,130 490,150 530,160 570,170" fill="none" stroke="blue" /> </svg>

The above illustration shows the general trend of decrease in metallic character and increase in non-metallic character over a period.

Group down

<svg width="200" height="400"> <line x1="100" y1="10" x2="100" y2="390" stroke="black" /> <line x1="100" y1="390" x2="40" y2="390" stroke="black" /> <text x="5" y="385">Metallic character</text> <line x1="100" y1="10" x2="160" y2="10" stroke="black" /> <text x="110" y="25">Non-metallic character</text> <polygon points="80,10 90,50 100,90 120,130 140,170 160,210 170,250 160,300 140,340 120,370 100,390" fill="none" stroke="blue" /> </svg>

The above graphic shows that metallic character increases while non-metallic character decreases as we go down the group.

Example

To make these tendencies more clear, consider the following examples:

Example 1: Group 1 elements (alkali metals)

The elements in group 1 display significant metallic properties. As you move down the group from lithium (Li) to francium (Fr), the atomic size increases, and they become more metallic. Lithium is the least metallic of the alkali metals, while francium is the most metallic.

Example 2: Group 17 elements (halogens)

Group 17 includes elements such as fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), which are known for their non-metallic properties. As you go down this group, the non-metallic properties decrease due to the increase in atomic size and decrease in electronegativities. For example, fluorine is the most non-metallic, while iodine is the least.

Example 3: Transition metals

The transition metals, found in groups 3-12, display transitional characteristics between metals and nonmetals. They generally display metallic properties, although their reactivity and specific characteristics can vary widely.

Conclusion

Metallic and nonmetallic properties are essential classifications in understanding chemical behavior. They arise from intrinsic properties of atoms, such as size, electronegativities, and ionization energies. Observing and predicting these trends helps chemists predict reactivity and other chemical properties, which is important for applications ranging from industrial chemistry to materials science.

Understanding the periodic trends of metallic and non-metallic properties helps students understand deeper aspects of chemistry and predict the behavior of elements in chemical interactions.


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