Define the terms with important points and examples: a).Nucleon b).Atomic number c).Atomic mass number d).Isotopes e).Atomic mass unit(amu) f).Relative atomic mass g).Molecule h).Radical i).Valency j).Variable valency k).Free radicals l).Formula m).Molecular Formula n).Relativ...
Define the terms with important points and examples: a).Nucleon b).Atomic number c).Atomic mass number d).Isotopes e).Atomic mass unit(amu) f).Relative atomic mass g).Molecule h).Radical i).Valency j).Variable valency k).Free radicals l).Formula m).Molecular Formula n).Relative Molecular Mass o).Empirical Formula
1. Nucleon : A proton or a neutron present in the nucleus of an atom of an element is called nucleon . Example: Carbon consist of 6 protons and 6 neutrons . i.e., there are 12 nucleons in C atom.
2. Atomic Number : The atomic number is the total number of protons present in the atom. Example : the atomic number of sodium is 11. i.e., it contains 11 protons and 11 electrons.
3. Atomic Mass Number : The atomic mass number of an atom is the total number of protons and neutrons (nucleons) present in the nucleus of the atom. It is represented as the superscript in the atomic symbol of an element. Example : - An atom of sodium is represented as 11Na23 where, 23 is the mass number of the element. This means, the number of protons in sodium is 11, and the number of neutrons is 23−11=12.
4. Isotopes : Isotopes are the elements having same atomic number but different mass number. They have same chemical properties as the number of valence electrons are same. Example : 6C12 ,6C13 , 6C14 are the three isotopes of carbon. They have same atomic number but different mass number due to difference in the number of neutrons.
5. Atomic Mass Unit : An atomic mass unit (symbolized AMU or amu) is defined as precisely 1/12 the mass of an atom of Carbon-12. The Carbon-12 atom has six protons and six neutrons in its nucleus. In imprecise terms, one AMU is the average of the proton rest mass and the neutron rest mass.
6. Relative Atomic Mass : Relative Atomic Mass is the ratio of the average mass per atom of an element from a given sample to 1/12 the mass of a carbon-12 atom. Example : the relative atomic mass of hydrogen is 1 and relative atomic mass of chlorine is 35.5
7. Molecule : Atoms of the same element or different elements which combine together to exist independently are called molecules. Example : O2 is the oxygen molecule most commonly found in the earth's atmosphere; it has two atoms of oxygen.
8. Radical : Radical is an atom, molecule, or ion that has an unpaired valence electron. A notable example of a radical is the hydroxyl (HO.) group, a molecule that has one unpaired electron on the oxygen atom.
9. Valency : Valency is defined as the number of hydrogen atoms which combine directly or indirectly with one atom of an element. Example: One atom of nitrogen combines with three atoms of hydrogen to form ammonia gas. So, the valency of nitrogen is 3.
10. Variable Valency : Some elements have different capacities to combine with different elements. This depends on the nature of reaction. This property of having different capacity to combine with different elements is called variable valency. Example : Iron exhibits two valencies 2 and 3. The Latin name of iron is Ferrum. For lower valency, it is written as Ferrous and the symbol is Fe2+. For higher valency, it is written as Ferric and the symbol is Fe3+.( Ferrous oxide valency of iron is +2, whereas in ferric oxide valency of iron is +3).
11. Free Radicals : Free radicals are very reactive neutral species which have one unpaired electron. Example: CH3(They are highly reactive thus they are very short lived).
12. Formula : A Formula is a user defined instruction to perform calculations. It is an expression that can include cell addresses, numbers, arithmetic operators and parenthesis. It begins with equal to (=) symbol, followed by cell references and operators. Example: Perimeter of rectangle = 2(length + width)
13. Molecular Formula : Molecular formula is a chemical formula of a compound existing as discrete molecules that gives total no. of each element in a molecule. Example: Molecular formula of oxygen is O2.
14. Relative Molecular Mass : The relative molecular mass of a substance is the ratio of the mass of a molecule of the substance to 1/12 the mass of an atom of Carbon 6C12 isotope.
15. Empirical Formula : Empirical Formula is the simplest formula of a compound which gives a ratio of different atoms present in one molecule of the compound. Example : One molecule of ethylene (molecular formula C2H4) contains two atoms of carbon and four atoms of hydrogen. Its empirical formula is CH2.
