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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.

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🧿 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