Why do atomic mass of element is different from actual atomic masses of the atoms of the - 12961022 1. you taken to measurement X Avogadro Number)/ Molecular weight. Type in your own numbers in the form to convert the units! ›› Quick conversion chart of atomic mass units to dalton. Thus, the molecular weight of a molecule is the total number of protons and neutrons in all the atoms in that molecule. Mass a full cup of beans. The intuition behind this hinges on how the atomic mass presented on the periodic table is calculated. Calculate the atomic mass of chlorine using the information provided in the following table. Boron-10 has an atomic mass of How would you approach these. Isotopes 36 and 37 are found in equal proportions. Monthly Notices of the Royal Astronomical Society, 2011. The atomic number does not necessarily have to be the same as the neutron number. The atomic mass of each element is listed below the symbol of the element in the periodic table: Cu = 63. There are 2 common isotopes of copper. 3) Weighted Average for All Atoms of an Element. where, A = Mass Number or Atomic Weight; Calculation of relative atomic mass or weight of an element is made easier here. The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope. Carbon exists as two major isotopes, 12C, and 13C ( 14C exists and has. How to calculate the atomic number, the atomic mass and charge or numbers of protons, neutrons, and electrons? Choose your element. Its unit is the unified atomic mass unit where 1 unified atomic mass unit is defined as 1⁄12 of the mass of a single carbon-12 atom, at rest. The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit (amu, also known as daltons, D). Atomic sizes are on the order of 0. Going back to 32 S, we know that because its molar mass is 31. short for relative atomic. From this data you will calculate the average mass of each isotope and the weighted average atomic mass of the element Beanium. The arbitrary standard that has been established for describing atomic mass is the atomic mass unit (amu or u), defined as one-twelfth of the mass of one atom of 12 C. Finally, add the atomic number and the number of neutrons to get the atomic mass. If you're given a list of isotopes to calculate, look for the exact mass of each isotope (that will be in decimal form, but if all you have are whole mass numbers, use those). This value on a periodic table is given in atomic mass units or amu , but for chemistry calculations, you usually write atomic mass in terms of grams per mole or g/mol. Molar mass is the sum of all of the atomic masses in a formula. The mass of a single atom of carbon-12 is defined as exactly 12 u. What is the most common isotope ofelement X?,. As we saw in our lesson on atomic structure, not all atoms of an element are identical. Mass Spectrometry Overview Mass Spectrometry is an analytic technique that utilizes the degree of deflection of charged particles by a magnetic field to find the relative masses of molecular ions and fragments. Using the chemical formula of the compound and the periodic table of elements, we can add up the atomic weights and calculate molecular weight of the substance. Also, explore tools to convert Atomic mass unit or kilogram to other weight and mass units or learn more about weight and mass conversions. The molar mass of HCl is 36. Using the atomic mass reported on the periodic table, determine the mass of bromine-81, the other isotope of bromine. 98161658 × 10-24 g. The problem may be reversed by asking you to calculate percentage abundance by providing other values such as isotope mass and average atomic mass. 73159744 * 10 26. d) AVERAGE ATOMIC MASS OF BEANIUM: _____ Isotope Average Mass of each Atom Relative Abundance = 1 2 3 Average Atomic Mass Conclusion Questions: Use the information from your data table to construct a cell for the Periodic Table. To calculate the averageatomic mass, multiply the fraction by the mass number for eachisotope, then add them together. In a naturally occurring sample of chlorine, we find that 75 per cent is chlorine-35 atoms and the other 25 per cent is chlorine-37 atoms. of atomic mass (and for unstable isotopes, radioactivity). 022×10^23 g 1 at. (b) Calculate the actual number of moles of aluminum reacted from the mass of foil reacted and the atomic mass of aluminum given on the Periodic Table of the Elements. using the average volume, calculate the molarity of the chloride ion in the I am doing a lab and need to calculate the change in temperature of Mixture Boron has two naturally occurring isotopes. The atomic mass is the number listed directly below the symbol for the element on the periodic table. Calculate the atomic mass of rubidium. 9048 amu, calculate silver's atomic mass. The molar mass of a chemical species is defined as the number of grams that one mole of a chemical weighs. Thus, the atomic mass measured in u has nearly the same value as the mass number. If the atomic mass of 25Mg is 24. Atomic mass is simply the sum of the atomic weights of all involved atoms. The unit of measure for mass is the atomic mass unit (amu). 968 amu and 36. 66053886 * 10 -24. 7%Therefore, Contribution of (_35^79)Br to atomic mass = (79*49. for ionic compounds e. This page is an activity meant to be worked through as a small group of ideally 4 people. It is measured in Atomic Mass Units. So he subtracts the atomic number from the atomic mass to get the number of neutrons. The term atomic mass is also often used (though technically, incorrectly) to refer to the average atomic mass of all of the isotopes of an element. Per the amu definition, a single 12 C atom weighs 12 amu (its atomic mass is 12 amu). 9%) of the mass of the atom. 2) Sum of Protons and Neutrons for a Single Atom. Add up the number of neutrons and protons in a single atom. All atoms of a particular element have the same number of protons. Average atomic mass is not a direct measurement of a single atom. 9%) of the mass of the atom. Atomic masses are calculated by figuring out the amounts of each type of atom and isotope there are in the Universe. Ace your school projects with these 12 featured Prezi presentations and templates; 30 August 2019. The mass in grams of one mole of any substance is its molar mass. Learn more about the differences between mass and weight, or explore hundreds of other calculators addressing the topics of fitness, math, finance, and health, among others. Hence while calculating mass of an atom we only add up the mass of proton and neutron. To calculate the atomic mass of a single atom of an element, add up the mass of protons and neutrons. Given information about an element, find the mass and name of an isotope. Chemistry studies the interaction of atoms and molecules on an atomic scale. 969 amu and % abundance = 75. 01 amu and B-11. Calculate the average atomic mass. of atomic mass (and for unstable isotopes, radioactivity). Boron-10 has an atomic mass of How would you approach these. For the best answers, search on this site https://shorturl. The mass of a single atom of carbon-12 is defined as exactly 12 u. 98161658 × 10-24 g. 7577 and a mass number of 35 amu. 6022 x 10-19 coulomb. The diﬀerence between the atomic mass and the nuclear mass is the atomic binding energy of the electrons, plus the rest mass of the electron. Note: Atomic mass unit is a metric unit of weight. Available here Image Courtesy:. Also, explore tools to convert Atomic mass unit or gram to other weight and mass units or learn more about weight and mass conversions. 9118 amu) and 87X (27. Atoms And Molecules (a) Ethyne, C 2 H 2 (Atomic mass of phosphorus = 31). average atomic mass for each element. The above information will be explained in more detail in the coming steps to share insight into how a mass spectrometrist can use a mass spectrum to determine the identity of an unknown chemical sample. In an atomic bomb, a mass of fissile material greater than the critical mass must be assembled instantaneously and held together for about a millionth of a second to permit the chain reaction to propagate before the bomb explodes. Or you can choose by one of the next two option-lists, which contains a series of common organic compounds (including their chemical formula) and all the elements. Since a molecule - scratch that, there we go again, calling everything molecules! Since a formula is made of atoms, we can calculate a formula mass by simply adding up all the atoms that are in it. To calculate the atomic mass of the individual atom, Add the no of protons with the no of neutrons of the molecule. Unfortunately, the mass number isn't listed on the Table of Elements. 87, quite a. However, mass is the amount of matter in an object and weight is the amount of mass times the gravitational pull on an object which makes atomic mass the preferred term. Then, have students calculate and estimate of the number of beans in the cup, based on the class average mass of one bean. Expressing Nuclear Binding Energy as Energy per Mole of Atoms, or as Energy per Nucleon; Determining the Mass Defect. All atomic masses are measured relative to the mass of the carbon-12 isotope. The isotopic mass. 98584 amu, and 26Mg is 25. Multiply the atomic mass of each isotope by its proportion in the sample. If the individual atomic masses of all the atoms in a formula are added together you have calculated the relative formula mass. Hello there trying to find calculating average atomic mass worksheet answers. 9118 amu) and 87X (27. The atomic weight is a weighted average of the atomic masses of an element's natural isotopes. The following equation is approximately true if one concedes that the mass of electrons is negligible. To calculate the mass of a single atom, first look up the atomic mass of from the periodic table. The atomic mass of an element is the average relative mass of its atoms as compared to an atom of carbon 12 taken. Atomic number and atomic masses If bromine atom is available in the form of, say, two isotopes (49. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of protons in an atom of an element is called its atomic number. Byju's Atomic Mass Calculator is a tool which makes calculations very simple and interesting. Generally, Density is= M/Vol. Why do we specify 12C? We do not simply state that the mass of a C atom is 12 AMU because elements exist as a variety of isotopes. Round all answers to two decimal places. The unit that is used for the. Because the definitions of both the mole and the atomic mass unit are based on the same reference substance, 12 C, the molar mass of any substance is numerically equivalent to its atomic or formula weight in amu. A look at how protons, neutrons and electrons make up atoms. 12 featured Prezi presentations and templates for engaging lessons. The mass of antimony-121 is 120. 100 cm 3 of this gaseous mixture was mixed with 190 cm 3 of oxygen and exploded. It becomes essential that we measure […]. 022×10^23 g 1 at. The term atomic mass is also often used (though technically, incorrectly) to refer to the average atomic mass of all of the isotopes of an element. It also looks at the problems. How to find the average atomic mass of an element. 10% abundant. We have simplified the entire process of calculating Atomic Mass. 007 825 032 23(9). Homework Equations Look below, i was able to solve A, however I am wondering why this number is only an approximate? Thanks! 3. number of neutrons = mass number - atomic number; Question. Atomic Mass Atomic mass is based on a relative scale and the mass of 12C (carbon twelve) is defined as 12 amu; so, this is an exact number. The Atomic mass unit [u] to kilogram [kg] conversion table and conversion steps are also listed. 02 * 10^17 = 10. 01 31 2 Alkali metals Alkaline earth metals Transition metals Lanthanides Actinides Other metals Metalloids (semi-metal) Atomic radius Nonmetals 6. Boron (B, element 5) has an atomic mass of 10. The intuition behind this hinges on how the atomic mass presented on the periodic table is calculated. Then, calculate the mass numbers. Atoms with the same atomic number, but. Formula of Atomic Mass: A = Number of protons + Number of neutrons. 70 g of pure M is obtained. If the substance is made of simple molecules, this mass may also be called the relative molecular mass. Position in atom: Protons are present in the nucleus of atom. Atomic Structure - Atomic massThis is a very prep-friendly lab for teachers to use when they wish to teach their students about atomic mass calculations. 229% are chlorine-37, calculate the atomic mass of chlorine. It is measured in Atomic Mass Units. Multiply the mass of each isotope by the % of the isotope 2. 47 percent) are 34. The peak with the highest mass is called the Molecular Ion , and the peak with the greatest abundance (largest size) is called the Base Peak. 46 grams of MO reacts with excess hydrogen gas according to the reaction shown below, 31. 02 * 10^17 = 10. Standard Atomic Weight The standard atomic weight is the average mass of an element in atomic mass units ("amu"). atoms & molecules. This table lists the mass and percent natural abundance for the stable nuclides. These two isotopes of bromine are present in. Find the average atomic mass for Li if 7. 98584 amu, and 26Mg is 25. The table contains some info on them. The unit of measure for mass is the atomic mass unit (amu). 7577 and a mass number of 35 amu. The formula mass is calculated by adding up all the atomic masses for every atom in the formula. Then, have students calculate and estimate of the number of beans in the cup, based on the class average mass of one bean. Calculate Average Atomic Mass. 7577 and a mass number of 35 amu. If you know the mass of the isotopes and the fractional abundance of the isotopes, you can calculate the element's atomic weight in atomic mass units (expressed as u, Da, or amu). How to convert pounds to atomic mass units [lb to u]: m u = m lb ×2. On the periodic table the mass of carbon is reported as 12. The chlorine isotope with 18 neutrons has an abundance of 0. Atomic mass is the combined mass of all the protons, neutrons, and electrons that make up an atom. 0625) the weight of an oxygen atom, but after 1961 based on 1/12 the weight of the carbon-12 atom. Solution: Molecular mass of silver bromide = 108 + 80 = 188 g. Use the atomic masses of each of the two isotopes of chlorine along with their percent abundances to calculate the average atomic mass of chlorine. There is another naturally occurring isotope of carbon, 13 C. 2 whose exact atomic mass is equal to the mass number. Name Period Date More Average Atomic Mass Calculate the average atomic masses. The other isotope, 65 Cu, has an abundance of 30. (remember that the sum of the two abundances must be 100). I would like to calculate the center of mass CM = (x_m,y_m,z_m) of all values. Molar mass of a gas. The mass calculator on the right may be used to calculate the exact mass of a molecule based on its elemental composition. They are equal to 11 and 23, respectively. 0) Calculate: (a) Moles of Nitric acid used (b) Moles of sodium carbonate in 25cm of the solution (c) Mass of unknown sodium. In order to calculate this quantity, the natural abundance and atomic mass of each isotope must be provided. This shared value between molar mass and atomic mass applies to all elements. Calculate Relative Atomic Weight (Amu) of an Element. Further data for radioisotopes (radioactive isotopes) of antimony are listed (including any which occur naturally) below. The atomic weight of an element depends on the abundance of its isotopes. The mechanisms by which atomic nuclei generate angular momentum of the γ-band are surface oscillations in the γ-soft structure or nuclear rotation in the γ-rigid structure. Average means across the different common isotopes. (a) Write the electronic arrangement of A and B. 84% Ag-107 with a mass of 106. Element X has three isotopes Isotope 1 Isotope 2 Isotope 3 Mass 28 29 30 Abundance % 92. In our example, krypton's mass number is 84 since its atomic weight, 83. This is the currently selected item. Instruct students to calculate the average mass of one bean in their group of 10. 54 (Rounded value) Atomic mass of 63 Cu = 62. You calculate the atomic mass of an element by taking the average mass of all of its atoms. The lower the atomic mass (and hence number) the less easy it is to detect. At standard temperature and pressure. When compared to protons or neutrons electrons have so much less mass that they don't influence the calculation. I would like to calculate the center of mass CM = (x_m,y_m,z_m) of all values. Before we begin to calculate the molar mass of NaCl or any other compound for that matter, it is important that we know what exactly the molar mass of an element is. 200 Ch Chemistrium □□□□□ 0. Multiply each mass by its corresponding percentage, and. Carbon, as we find it in our universe, does not exist as solely as 12 C. 7577 and a mass number of 35 amu. Take care to determine which mass you use from tables in the literature. 47 percent) are 34. Calculating Atomic Mass. This tutorial shows the steps needed to calculate atomic mass depending on the type of problem you are working. The molar mass is calculated by adding up the relative atomic weights of each element in a chemical species according to the chemical formula of that species. The following is the equation for the atomic weight of an element: A l = m sample /((1/12)*m carbon12) In this equation, A l is atomic weight to be determined, and m sample is the average atomic mass of the element in consideration. Also, explore tools to convert Atomic mass unit or kilogram to other weight and mass units or learn more about weight and mass conversions. Iron 57 Metal is one of over 250 stable Metallic isotopes produced by American Elements for biological and biomedical labeling, as target materials and other applications. Solution: 1) The first relevant equation: (36 x a) + (37 x a) + (39 x b) = 38. Occupying a volume whose radius is 1/100,000 the size of the atom, the nucleus contains most (99. 9% respectively. What is this element? Chromium has the following isotopic masses and relative abundances. isotopes amu abundance 24Mg 23. is the mass of an atom in atomic mass units (amu) Micro World. Because the definitions of both the mole and the atomic mass unit are based on the same reference substance, 12 C, the molar mass of any substance is numerically equivalent to its atomic or formula weight in amu. 7577 and a mass number of 35 amu. Atomic number and mass number can also be represented on the symbol of an element as follows: Let's take an example: Represent the atom of sodium whose atomic mass is 23 and atomic number is 11. Though individual atoms always have an integer number of atomic mass units, the atomic mass on the periodic table is stated as a decimal number because it is an average of the various isotopes of an element. The diﬀerence, or about 26. To calculate the atomic mass of a single atom of an element, add up the mass of protons and neutrons. The following equation is approximately true if one concedes that the mass of electrons is negligible. The standard atomic weight was determined by combining (1) the best calibrated isotope-ratio measurement of magnesium in DSM3 isotopic reference material (a mono-elemental nitric solution of magnesium), and (2) the relative isotope-ratio differences between other magnesium-bearing materials and DSM3. amu (atomic mass unit) : the standard unit of measurement of atomic mass. Show Step-by-step Solutions. 93u and copper-65 with an atomic mass of 64. On the periodic table the mass of carbon is reported as 12. (c) Number of H-ions in 4. This page looks at the information you can get from the mass spectrum of an element. Atomic weight is the average mass of all of the naturally-occurring isotopes of an element. You will get the answer for Atomic Mass without getting into the complex process of actually calculating anything. Isotope Mass / Da Natural abundance (atom %) Nuclear spin (I). Use this to determine whether iron expands or contracts when it undergoes transformation from the BCC to the FCC structure. Molar Mass of a Hydrate (Molar Mass, Molecular Weight, Gram Formula Mass) Mole Conversions. I thought this must be a trivial problem, but I can't find a solution to it in the internet. This is the average atomic mass of carbon. 7MeV, is released as heat, except for ≈ 0. Let us go over a couple of examples on how to calculate the average atomic mass based on the atomic masses of the different isotopes and the natural abundance. There is another naturally occurring isotope of carbon, 13 C. The difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed is called the mass defect. Use this information to determine which isotopes of Br occur in nature. What is the mass (in amu) of a carbon-12 atom? 3. We are told what mass and atomic numbers are, and how they tell us the number of subatomic particles that are present in atoms. Chemistry computing formula mass worksheet. A 3 molar 2 N = a V, where. The average atomic mass between these two isotopes is 63. Mass, molar concentration, volume, and formula weight are related to each other as follows: Mass (g) = Concentration (mol/L) * Volume (L) * Formula Weight (g/mol). When compared to protons or neutrons electrons have so much less mass that they don't influence the calculation. Mass number = Atomic number + number of neutrons. The Periodic Table with Atomic Mass will give you the atomic weight, or atomic mass, of the elements. 1 NSCL-Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321, USA. 5) or molecular mass for covalent elements or compounds. The mass number of an atom is the number of nucleons (the number of protons + the number of neutrons). Since 1961 the standard unit of atomic mass has been one-twelfth the mass of an atom of the isotope carbon-12. 3) Weighted Average for All Atoms of an Element. The atomic mass of lead is. 1 nm = 1 Angstrom = 10-10 m Nuclear sizes are on the order of femtometers which in the nuclear context are usually called fermis: 1 fm = 10-15 m. For 12 C the atomic mass is exactly 12u, since the atomic mass unit is defined from it. im/Da5b5 What grade are you? hummm high school I imagine Go to Google Type in your question: " How do I calculate the average atomic mass of copper" Hit "Search" key you will see list of sites Click: "Chemistry: Average Atomic Mass" Not sure if you can follow it but since you asked the question my guess is that you can. The key difference between atomic mass and molecular weight is that the atomic mass is the mass of a single atom whereas the molecular weight is the sum of the weights of the atoms in the molecule. "B" refers to the first isotope's atomic mass and "c" refers to the second isotope's atomic mass. Gram is a metric unit of weight. Calculate the average atomic mass of neon. Atomic masses are calculated by figuring out the amounts of each type of atom and isotope there are in the Universe. What exactly is molar mass, and how is it used? The molar mass of a compound (sometimes to referred to as molecular weight) is the cumulative atomic weight of all the atoms/elements in the compound. The Periodic Table with Atomic Mass will give you the atomic weight, or atomic mass, of the elements. mass just like each skittle does not have the same mass. Atomic Mass Chart Unique How to Calculate atomic Mass Lovely atomic Mass Chart - From the thousand photographs on the internet with regards to atomic mass chart, choices the best series using ideal quality exclusively for you, and now this pictures is actually one of graphics selections within our greatest photos gallery in relation to Lovely. It is defined to be 1/12 of the mass of one atom of carbon-12 and in older works is also abbreviated as "amu". The mechanisms by which atomic nuclei generate angular momentum of the γ-band are surface oscillations in the γ-soft structure or nuclear rotation in the γ-rigid structure. 10% abundant. 3) Weighted Average for All Atoms of an Element. Calculate the atomic mass of metal m A certain metal oxide has the formula MO. The mass is not a whole number because of isotopes. The mass of a proton ,neutron and electron is approximately 1u,1u and 0. Atomic Mass "An atomic weight (relative atomic mass) of an element from a specified source is the ratio of the average mass per atom of the element to 1/12 of the mass of 12 C" in its nuclear and electronic ground state. "Chemquest 9 Average Atomic Mass Density Practice Problem Worksheet Answers Density Worksheet With Answers calculate density worksheet with from Density Practice. 0151223 amu and 92. Hence it is also known as nucleon number. To accomplish this, we usually use an approach called the weighted average. For example, all hydrogen atoms, and only hydrogen atoms, contain one proton and have an atomic number of 1. To determine the number of protons in neutrons in an item you first need to get a periodic table. For other isotopes, the isotopic mass usually differs and is usually within 0. If you liked this video, please subscribe to my channel by clicking on the YouTube button!. Multiply the mass of each isotope by the % of the isotope 2. This relationship can be given as follows. Calculate the atomicity of a gas X (atomic number 35. All you have to do is provide the input values and hit calculate. The atomic mass unit (u) is defined as a mass equivalent to 1 / 12 of the mass of one atom of carbon-12. For your material, The M= (Mass. 0000), is. Three experimental facts are required to determine the atomic radius of a metallic element such as polonium: density, molar mass and crystal structure. The arbitrary standard that has been established for describing atomic mass is the atomic mass unit (amu or u), defined as one-twelfth of the mass of one atom of 12 C. We know that all things around us are occupied by matter whose building block is molecules. If the atomic mass of^25 Mg is 24. Calculate the average atomic mass of lithium, which occurs as two isotopes that. We are told what mass and atomic numbers are, and how they tell us the number of subatomic particles that are present in atoms. Atomic mass is really a weighted average of all the element's isotopes based on their natural abundance on Earth. 1 nm = 1 Angstrom = 10-10 m Nuclear sizes are on the order of femtometers which in the nuclear context are usually called fermis: 1 fm = 10-15 m. This is also the mass in grams of 1 mole of. 79 * 10^-16 g * 6. Calculate the atomic mass of rubidium. The peak with the highest mass is called the Molecular Ion , and the peak with the greatest abundance (largest size) is called the Base Peak. The chlorine isotope with 18 neutrons has an abundance of 0. Isotope Distribution Calculator and Mass Spec Plotter Mass Spectrum Generator Exact Mass Calculator, Single Isotope Version SIS Online GC Chromatogram and Mass Spectrum Viewer Search NIST 17 and Wiley MS Databases Mass Spec Calibration Compounds and Spectra Exact Masses of the Elements and Isotopic Abundances. Atomic mass and atomic weight are terms used interchangeably. Iron 57 Metal is one of over 250 stable Metallic isotopes produced by American Elements for biological and biomedical labeling, as target materials and other applications. 98584 amu, and^26 Mg is 25. The intuition behind this hinges on how the atomic mass presented on the periodic table is calculated. In this movie, we show how to calculate the molecular weight of a substance from the atomic weights given on the periodic table. This shared value between molar mass and atomic mass applies to all elements. Molar mass is the mass of one mole per single element while atomic mass is the mass of an atom at rest or is the number of protons and neutrons. 968 amu and 36. Generally, Density is= M/Vol. Need desperate help Question 1 Use the follo. 70% of all magnesium Mg-25 has a mass of 24. 6 C Carbon 12. If one knows the atomic number Z of an atom and its neutron number N, then one can also calculate the atomic mass of the atom, also referred to as A. 00 In this simulation,. the mass of an isotope of an element in atomic mass units 2. The atomic mass of an element is the average mass of one atom in a sample of the element that contains all the element's isotopes, where the relative amounts of isotopes are the same as the relative amounts found in nature. The units for molar mass are g mol -1 or grams per mole. Mass number = Atomic number + number of neutrons. Examples: Let's determine the number of protons, neutrons, and electrons in the following isotopes. Look up the mass of each isotope. An atomic mass unit is approximately 1. 9118 amu) and 87X (27. 1 By definition: 1 atom 12C "weighs" 12 amu. 14 g of oxygen: 1. Calculating the Atomic Mass of an Element. The relative abundance of these 3 isotopes are Calculate the average atomic mass of neon from the following data.