![]() An atom can be defined more accurately as (a) the smallest indivisible parts of an element that can take part in a chemical reaction (b) the smallest part of an element that can take part in a chemical reaction (c) a combination of protons, neutrons. ![]() The atomic number of an element is precisely (a) the number of protons in the atom (b) the number of electrons in the atom (c) the number of neutrons in the atom.New School Chemistry for SSS by O.Y Ababio.If an element R has isotopes 60% 12R 6 and 40% xR 6 and the relative atomic mass of R is 12.4, find x. State the number of electrons, protons and neutrons present in the following atoms/ionsģ. Give two examples of other elements which exhibit the phenomenon illustrated.Ģ. State the relationship between the two atoms.Ĭ. The value of m is 18 GENERAL EVALUATION/REVISIONĪ. An element with relative atomic mass 16.2 contains two isotopes 16P8 with relative abundance 90% and mP8 with relative abundance 10%. What is the relative atomic mass of the element?Ģ. The following are more examples of calculations of relative atomic masses of elements.Īn element Y exist in two isotopic forms 39Y 18 and 40Y 18 in the ratio 3:2 respectively.A given quantity of chlorine contains 75% 35Cl 17, and 25% 37Cl 17, determine the relative atomic mass of chlorine.How many neutrons are present in the isotope 37Cl 17 ?.Calculate the mean relative atomic mass of X.How many neutrons are present in the isotope 41X.X is an element which exists as an isotopic mixture containing 90% of 39X 19 and 10% of 41X 19.The following is an example of calculation of the relative atomic mass of an element from percentage abundance of its isotopes. The atoms that exhibit isotopy are called ISOTOPES.Įxamples of atoms that exhibit isotopy are chlorine 35Cl and 37Cl ![]() This is due to the difference in the number of neutrons present in the atoms. Isotopy is the occurrence of atoms of elements having the same atomic number but different mass numbers. Mass Number = Number of proton + Number of neutron ![]() Mass number or atomic mass of an element is the sum of the number of protons and neutrons in the nucleus of its atom. The atomic number of an element is the number of protons in the nucleus of its atom. Proton has a positive charge, an electron has a negative charge and neutron has no charge. Enjoy the class! ATOMIC NUMBER, MASS NUMBER, ISOTOPES AND CALCULATIONSĪtoms are made up of sub-particles. In today’s class, we will be talking about atomic number, mass number, isotopes and calculations. ![]()
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