Therefore, Na atom has more electrons (11) than Na+ ion (10). There are two main ways in which scientists frequently show the mass number of an atom they are interested in. (c) These isotopes differ in their masses. Chapter 5 Class 9 - The Fundamental Unit of Life. Answer: For example, The electronic configuration of potassium (K) is 2,8,8, 1 instead of 2,8,9 though the M shell can accommodate up to 18 electrons. NCERT Solutions for Exercise 4.1, Class 11, Mathematics, NCERT Solutions for Chapter 3, Miscellaneous Exercise, Class 11, Mathematics, NCERT Solutions for Exercise 3.3, Class 11, Mathematics, NCERT Solutions for Exercise 3.2, Class 11, Mathematics, NCERT Solutions for Exercise 3.1, Class 11, Mathematics. An element is represented as 168X. The term was first used by Margaret Todd, a Scottish doctor, and writer while consulting with radiochemist Frederick Soddy. Please login :). same chemical properties. Question 2. (a) Number of protons, electrons and neutrons in X. As a few alpha particles suffered minor deflections and a very few major deflections, this means that these must have met with some obstructions in their path. Three elementary particles which constitute an atom are ; electron (e), proton (p) and neutron (n). How many valence electrons does it have ? (CBSE 2014, 2016) Carbon atoms with 7 neutrons have an atomic mass of 13 (6 protons + 7 neutrons = 13). Answer: Required fields are marked *. Get Instant Solutions, 24x7 No Signup required download app Related questions . Answer: \[\text{atomic number} = \left( \text{number of protons} \right) = 19\]. (a) In the gold foil experiment, what observations led Rutherford to conclude that However, their atomic numbers are the same. You can specify conditions of storing and accessing cookies in your browser, Define isotopes. (ii) Atomic no. For chlorine, Z = 17, A = 35. Atoms of the same element that differ in their numbers of neutrons are called isotopes. A lithium atom contains 3 protons in its nucleus irrespective of the number of neutrons or electrons. Luckily, aside from having different masses, most other properties of different isotopes are similar. The symbol notations for elements are represented as follows : (iii) Centre is positively charged. Knowing the differences allows us to distinguish between one isotope from another. Please note that the difference in the mass numbers of the isotopes is because of the difference in the number of neutrons present. Example: Isotopes of Hydrogen - Protium, Deuterium, Tritium, Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class, CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. All three isotopes of hydrogen have identical . Click Start Quiz to begin! (b) Mass number of an element X. Why do isotopes have different physical properties?a)Isotopes of an element have different electronic configuration.b)Isotopes have same atomic number.c)Isotopes of an element have different mass number.d)Isotopes of an element have different atomic number.Correct answer is option 'C'. same atomic number but different mass number. State whether the following statements are true or false. Atomic mass is the sum of some protons and the number of neutrons and atomic number is equal to the number of protons. (b) Mass of atom is distributed evenly within it. This is because an additional number of neutrons compensates for the difference in the number of nucleons. These atoms are the isotope called carbon-13. of p = 17 The first stable isotope in neon was discovered by Thomson. Question 16. Weve got your back. For instance, lithium exists as an isotope with 3 neutrons, and as an isotope with 4 neutrons, but it doesn't exist as an isotope with 2 neutrons or as an isotope with 5 neutrons. Required fields are marked *, Physical And Chemical Properties of Isotopes, Test your knowledge on periodic table isotopes element. No worries! It has only one shell (K shell) which can have maximum of two electrons only. But when you measure the weight of these two things then you find that they are different. Valency of X = (8 7) = 1 (ii) Some -particles (positively charged) were deflected and a few came back in the same direction. (i) Mass no. Generally, elements which have odd atomic numbers will have one or two stable isotopes whereas elements with even atomic numbers will mostly have 3 or more stable isotopes. Most hydrogen atoms have just one proton and one electron and lack a neutron. (CBSE 2011, 2016) It's sometimes written like this, in fact it's often written like this, chlorine 35 and this isotope notation that you see over here where we have 35 in the top left, that 35 is the sum of this version, this isotope of chlorines protons and neutrons. (it) 8p + 9n It is directed away from the nucleus. (CBSE 2015) (b) Isobars may be defined as : the atoms belonging to the different elements with same mass numbers but different atomic numbers. Number of protons and electrons in isobars is different . the number of protons in all the atoms of a particular element is same, therefore to have different mass numbers, isotopes contain different number of neutrons. //
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