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Date: 25-4-2017
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Date: 26-11-2020
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Date: 25-3-2017
1955
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Isotopes
Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Most elements have a few stable isotopes and several unstable, radioactive isotopes. For example, oxygen has three stable isotopes that can be found in nature (oxygen-16, oxygen-17, and oxygen-18) and eight radioactive isotopes. Another example is hydrogen, which has two stable isotopes (hydrogen-1 and hydrogen-2) and a single radioactive isotope (hydrogen-3).
The isotopes of hydrogen are unique in that they are each commonly referred to by a unique name instead of the common chemical element name. Hydrogen-1 is almost always referred to as hydrogen, but the term protium is infrequently used also. Hydrogen-2 is commonly called deuterium and symbolized 21D. Hydrogen-3 is commonly called tritium and symbolized 31T. This text will normally use the symbology 21H and 31H for deuterium and tritium, respectively.
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إجراء أول اختبار لدواء "ثوري" يتصدى لعدة أنواع من السرطان
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دراسة تكشف "سببا غريبا" يعيق نمو الطيور
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قسم الشؤون الفكرية يقيم برنامج (صنّاع المحتوى الهادف) لوفدٍ من محافظة ذي قار
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الهيأة العليا لإحياء التراث تنظّم ورشة عن تحقيق المخطوطات الناقصة
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قسم شؤون المعارف يقيم ندوة علمية حول دور الجنوب في حركة الجهاد ضد الإنكليز
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وفد جامعة الكفيل يزور دار المسنين في النجف الأشرف
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