Modern periodic law// about of modern periodic law// periodic table

 

Modern Periodic Law is one of the most important concepts in chemistry that explains the arrangement of elements in the modern periodic table.

🔬 Modern Periodic Law:

"The physical and chemical properties of the elements are a periodic function of their atomic numbers."

📘 Explanation:

  • This means that if the elements are arranged in the order of increasing atomic number, their properties repeat at regular intervals.
  • It was proposed by Henry Moseley in 1913, based on his experiments with X-rays.
  • The atomic number (Z) is the number of protons in the nucleus of an atom, and it determines the identity and properties of the element.

🧪 Significance of Modern Periodic Law:

  • Solved problems with Mendeleev’s periodic table, where elements were arranged by atomic mass.
  • Helped correctly place elements like Argon (18) before Potassium (19), even though Argon has more mass.
  • Justified the existence of isotopes as they have the same atomic number but different masses.
  • Basis of the modern periodic table, which has 7 periods and 18 groups.

📊 Modern Periodic Table:

  • Elements are arranged in rows (periods) and columns (groups).
  • Elements in the same group have similar chemical properties because they have the same number of valence electrons.

🧠 Example:

  • Lithium (Z = 3), Sodium (Z = 11), Potassium (Z = 19) — All have similar properties and are placed in the same group (Group 1) because they all have 1 electron in their outermost shell.

Let me know if you want a Hindi explanation or a PDF of this topic!

Comments

Post a Comment

Popular posts from this blog

Faraday's First Law of Electrolysis (Chemistry, Class 12):

  Faraday's First Law of Electrolysis (Chemistry, Class 12): Statement: The mass (m) of a substance deposited or liberated at an electrode during electrolysis is directly proportional to the quantity of electricity (Q) passed through the electrolyte. Mathematically: m=Z.Q Where: m = mass of the substance deposited (in grams) Q = total charge passed (in coulombs) Z = electrochemical equivalent (ECE) of the substance (grams per coulomb) Also, Q = I.t I = current (in amperes) t = time (in seconds) So, m = Z.I.t In Simple Words: Faraday's First Law tells us that more electricity means more substance will be deposited at the electrode. For example, if you double the current or time, the amount of substance deposited will also double. If you want the Second Law of Faraday or its explanation in Hindi , just let me know!
Read more

What is electromotive force in Chemistry class 12th

  In chemistry , electromotive force (EMF) refers to the voltage generated by a chemical cell (like a galvanic or voltaic cell) due to redox (reduction-oxidation) reactions happening at the electrodes. 🔹 Definition (Chemistry Context): EMF is the potential difference between two electrodes of an electrochemical cell when no current is flowing . It measures the tendency of electrons to flow from the anode (where oxidation occurs) to the cathode (where reduction occurs). 🔹 Symbol: 🔹 Unit: Volt (V) 🔹 Formula: \mathcal{E}_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} Where: = standard electrode potentials (in volts) Measured under standard conditions : 1 M concentration 25°C (298 K) 1 atm pressure 🔹 Example (Daniel Cell): Zn | Zn²⁺ (1 M) || Cu²⁺ (1 M) | Cu Anode (oxidation): Zn → Zn²⁺ + 2e⁻ Cathode (reduction): Cu²⁺ + 2e⁻ → Cu Standard electrode potentials: \mathcal{E}_{\text{cell}} = 0.34 - (-0.76) = 1.10\text{ V}...
Read more

What is means of isolated gaseous atom

  💨 Isolated Gaseous Atom – Meaning: An isolated gaseous atom means: 👉 A single atom of an element 👉 In the gaseous state (not bonded to any other atom or molecule) 👉 That is completely free from external forces (like other atoms or molecules nearby) 🧪 In Simple Words: An isolated gaseous atom is a lone atom in the gas phase, existing independently , just like: A single He atom (Helium) floating alone in space Not forming a molecule like O₂ or H₂ Not in solid or liquid form 🔍 Why Important in Chemistry? It is a reference state used in: Ionization energy Electron affinity Enthalpy calculations Bond dissociation energies These properties are usually measured for an isolated gaseous atom because: There's no interference from other atoms. It gives the purest form of an element's energy or behavior. 🧠 Example: If we say: "The ionization energy of an isolated gaseous hydrogen atom is 1312 kJ/mol" It means: the energy required...
Read more