Approximate percentage of elements in Human body

• Oxygen - 65%
• Carbon - 18%
• Hydrogen - 10%
• Nitrogen - 3%
• Calcium - 2%
• Phosphorous - 1%
• Potassium - 0.35%
• Sodium - 0.15%
• Chloride - 0.15%
• Magnesium - 0.05%
• Iron - 0.0004%

✅ Atomic and Molecular Masses

➖Atomic Mass:
Mass of an atom.
Reported in atomic mass unit “amu” or unified mass “u”
One atomic mass unit i.e. amu, is the mass exactly equal to one-twelfth the mass of one carbon-12 atom.

➖Molecular Mass:
Mass of a molecule of covalent compound.
It is equal to the sum of atomic masses of all the elements present in the molecule.
Formula Unit Mass
Mass of a molecule of an ionic compound
It is also equal to the sum of atomic masses of all the elements present in the molecule

✅ Mole Concept:

➖Mole:
Unit of amount of substance.
One mole amount of substance that contains as many particles or entities  as there are atoms in exactly 12 g of the 12C isotope.

➖Molar mass:
Mass of one mole of a substance in gram
Molar mass in gram in numerically equal to atomic/molecular/formula mass in amu or u.

Good Morning 🌄🌄

🧿 Radioactivity 🧿

➖The process of emission of particles from nuclei because of the nuclear instability; is known as radioactivity.
➖The substance that releases such energy/rays is known as radioactive substance.
➖The invisible rays released from such radioactive substance are known as radioactive rays.
➖Likewise, radioactivity is a nuclear phenomenon that happens (naturally) because of the nuclear instability of atoms.
➖In 1896 Henri Becquerel first observed the phenomena of radioactivity, but the term ‘radioactivity’ was coined by Marie Curie.
➖Marie Curie discovered the radioactive elements namely Polonium and Radium in 1898.
➖For her discovery, Marie Curie won the Nobel Prize.


✅Radioactive Rays
➖After long years of experiment, Ernest Rutherford along with his colleague (Hans Geiger and his student Ernest Marsden), discovered alpha rays, beta rays, and gamma rays.
➖These rays emitted as the result of the disintegration of atoms.


✅Alpha (α) Particles
➖Alpha particles are usually composed of two protons and two neutrons, which are tightly bound together.
➖Alpha particles are being released during radioactive decay (or alpha decay) from the nucleus radio nuclides.
➖The alpha particles are identical to the nucleus of either normal helium atom or doubly ionized helium atom.
➖In comparison to other particles (i.e. Gamma and Beta), alpha particles are heavy and slow. Therefore, alpha particles have very small range in the air.
➖Because of slow speed, Alpha particles have very weak penetrating powers; these particles are even stopped by a thin paper sheet (see image given above).
➖Because of having the double positive charge, alpha particles are highly ionizing.


✅Beta (β) Particles
➖Beta particles are the fast moving electrons emitted by some radio nuclides during the radioactive decay (also known as beta decay).
➖Beta particles are of much lighter weight and carry a single negative charge.
➖Beta particles are rarely ionizing than the alpha particles.
➖Because of having lighter weight, beta particles can travel much farther than alpha particles; however, beta particles can be stopped by several sheet of papers or one sheet of aluminum.
➖Beta particles are negatively charged and get attracted towards positively charged particles.


✅Gamma (ү) Particles
➖Gamma particles are the bundle of high energy namely electromagnetic energy (photon) emitted by the radioactive elements during the radioactive decay.
➖Among all three particles (alpha, beta, and gamma), gamma particles are the most energetic photons.
➖Gamma particles, which are the form of electromagnetic radiation(EMR), originate from the nucleus.
➖The wavelengths of gamma are the shortest among all three.
➖Gamma particles have no charge and they are neutral; therefore, they are unaffected by magnetic and electric fields.


✅Uses of Radioactive Elements
➖Medical field (treatment of many diseases)
➖Industrial process
➖Energy production – Nuclear reactors

♻️ Important Scientific Laws and Theories ♻️
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🔹 Ohm's Law - It states that the current passing through a conductor between two points is directly proportional to the potential difference across the two points provided the physical state and temperature etc. of the conductor does not change.

🔹 Pauli exclusion principle - It explains that no two electrons in the same atom or molecule can have the same set of quantum numbers.

🔹 Raman effect - It is the change in wavelength that occurs when light is scattered by the atoms or molecules in a transparent medium.

🔹 Tyndall effect - The scattering of light by very small particles suspended in a gas or liquid.

🔹 Boyles's Law - It states that temperature remaining constant, volume of a given mass of a gas varies inversely with the pressure of the gas. Thus,
PV = K (constant), where, P = Pressure and V = Volume.

🔹 Charles's Law - It states that pressure remaining constant, the volume of a given mass of gas increases or decreases by 1/273 part of its volume at 0 degree celsius for each degree celsius rise or fall of its temperature.

🔹 Coulomb's Law - It states that force of attraction or repulsion between two charges is proportional to the amount of charge on both charges and inversely proportional to the square of the distance between them.

🔹 Heisenberg principle (uncertainty principle) - It is impossible to determine with accuracy both the position and the momentum of a particle such as electron simultaneously.

🔹 Archimede's principle - It states that a body when wholly or partially immersed in a liquid, experiences an upward thrust which is equal to the weight of the liquid displaced by it. Thus, the body appears to lose a part of its weight. This loss in weight is equal to the weight of the liquid displaced by the body.

🔹 Aufbau principle - It states that in an unexcited atom, electrons reside in the lowest energy orbitals available to them.

🔹 Avogadro's Law - It states that equal volumes of all gases under similar conditions of temperature and pressure contain equal number of molecules.

🔹 Brownian motion - It is a zigzag, irregular motion exhibited by small solid particles when suspended in a liquid or gas due to irregular bombardment by the liquid or gas molecules.

🔹 Bernoulli's principle - It states that as the speed of a moving fluid, liquid or gas, increases, the pressure within the fluid decreases. The aerodynamic lift on the wing of an aeroplane is also explained in part by this principle.

🔹 Gay-Lussac’s Law of combining volumes - Gases react together in volumes which bear simple whole number ratios to one another and also to the volumes of the products, if gaseous — all the volumes being measured under similar conditions of temperature and pressure.

🔹 Graham’s Law of Diffusion - It states that the rates of diffusion of gases are inversely proportional to the square roots of their densities under similar conditions of temperature and pressure.

🔹 Kepler's Law - Each planet revolves round the Sun in an elliptical orbit with the Sun at one focus. The straight line joining the Sun and the planet sweeps out equal areas in equal intervals. The squares of the orbital periods of planets are proportional to the cubes of their mean distance from the Sun.

🔹 Law of Floatation - For a body to float, the following conditions must be fulfilled: The weight of the body should be equal to the weight of the water displaced and the centre of gravity of the body and that of the liquid displaced should be in the same straight line.

🔹 Law of conservation of energy - It states that energy can neither be created nor destroyed but it can be transformed from one form to another. Since energy cannot be created or destroyed, the amount of energy present in the universe is always remain constant.