Module 1 1.5a - isotopes

26 Aug 2015
1 sur 15

Module 1 1.5a - isotopes

• 2.  To describe an isotope  To explain how atomic mass can vary within one element  To calculate the abundance of different isotopes
• 3.  An element is usually defined by the number of protons in the nucleus  If the number of protons changes the element changes  The number of protons is equal to the number of electrons in an atom  However the number of neutrons can change between different atoms of the same element
• 4.  An isotope is a chemical with a different atomic mass but the same number of protons as another  Take carbon as an example
• 5.  The atomic mass of carbon on the periodic table is 12.011  This is the mean mass of carbon on Earth
• 6.  To calculate the abundance of one isotope it is important to know the mass of all isotopes and the mass on the periodic table  We are going to calculate the % abundance of carbon 12
• 7. It is firstly important to understand the concept of proportions and percentages Carbon 12 + carbon 14 = 100% of all carbon We are trying to find the % of 12C so we will call that x This means that: 12x + (100-x)14 / 100= 12.011 where x is % carbon 12, (100-x) is % carbon 14
• 8. 12x + (100-x)14/100 = 12.011 Multiply out the brackets 12x + 1400-14x /100= 12.011 Multiply by 100 to remove the /100 12x +1400 -14x = 1201.1 Subtract the whole number leaving only x on one side 12x – 14x = -198.9 -2x=-198.9 -x = 99.45 x = 99.45
• 9.  Research to find an element that has 2 common isotopes  Calculate the relative abundances of these 2 isotopes – If you find a website that offers you the information ensure that it is the correct answer!  Write out an exam style question and give it to your neighbour
• 10. Average atomic mass = (abundance of isotope 1)(mass of isotope 1) + (abundance of isotope 2)(mass of isotope 2)
• 11. Isotope Isotopic mass (u) Isotopic abundance (%) 24Mg 24 78.99 25Mg 25 10.00 26Mg 26 11.01
• 12. (24)(0.7899)+(25)(0.10)+(16)(0.1101)= 18.9576 + 2.5 + 2.8626 = 24.3202
• 13.  You will be given an element from the periodic table  You will produce a short (3-4 minute) presentation about that element  The presentation MUST include the electronic structure, isotopes of the element, symbol and position on the periodic table  It should also include uses of the element, how it was discovered, impact of uses of the element (if applicable)
• 14.  The student explains how science is applied and how it may be used to address a specific problem or issue in a local or global context.  The student discusses the effectiveness of science and its application in solving the problem or issue.  The student discusses and evaluates the implications of the use and application of science interacting with at least two of the following factors: moral, ethical, social, economic, political, cultural and environmental.
• 15.  The student uses sufficient scientific language correctly.  The student communicates scientific information effectively.  When appropriate to the task, the student fully documents sources of information correctly.