# Atomic Mass Formula

59 amu, S = 32. This problem can also be reversed, as in having to calculate the isotopic abundances when given the atomic weight and isotopic weights. none of these ANS:B 37. Example the relative formula mass of water (H 2 O) is: Relative atomic mass of Hydrogen = 1. 0000 atomic mass units. 72 g of X, then Find atomic mass of X?. Elemental Formula utility calculates the possible compositions of an ion given its mass. So, in calculating relative atomic mass you must take into account the different isotopic masses of the same elements, but also their % abundance in the element. Mass is a measure of the total amount of matter in an object. calculate the valency and exact atomic mass of an element. However, 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. Also, explore tools to convert Atomic mass unit or gram to other weight and mass units or learn more about weight and mass conversions. Their masses are reffered to as atomic masses and formula masses respectively and are expressed in amu. Use the "Hint" button to get a free. The formula mass of sodium chloride is equal to the sum of the atomic masses of sodium and chlorine, which can be found on the periodic table. The Semiempirical Formula for Atomic Masses Prout's Rule In the early years of the nineteenth century when atomic theory was being developed an English physician named William Prout became interested in measuring the relative masses of different types of atoms. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has. Air is a mixture of several gases, where the two most dominant components in dry air are 21 vol% oxygen and 78 vol% nitrogen. Note that rounding errors may occur, so always check the results. Chapter 1—The Atomic Nature of Matter: Selected Questions for Practice Exam. Beginning chemists fill in the blanks, which may include the atomic number, atomic mass, atomic symbol, or element name. Elements in Number of atoms Atomic Total the compound of each element Weight Mass. The formula for carbon dioxide is CO 2, that means one atom of carbon and two atoms of oxygen. Gram is a metric unit of weight. 59, but we can round that to 201 (this is known as the mass number). Relative atomic mass = Mass of 1/12 of an atom of carbon-12 Mass of one atom of the element 7. /> Answer sheet now uploaded, please notify me of any errors. Typical unit is g/mol. 00727648749486 Atomic mass unit [u] From: kilogram gram exagram petagram teragram gigagram megagram hectogram dekagram decigram centigram milligram microgram nanogram picogram femtogram attogram dalton kilogram-force second²/meter kilopound kip slug pound-force second²/foot pound pound (troy or apothecary) ounce ounce (troy. Use this information to determine which isotopes of Br occur in nature. freesciencelessons. This is a very primitive exact mass calculator. Please provide values below to convert Atomic mass unit [u] to kilogram [kg], or vice versa. One atomic mass unit is equal to 1. Notes on the Atomic Mass of particular elements: Technetium: Atomic mass number given for longest lived isotope. Atomic mass is also the number of protons and the number of neutrons. How many grams in an atomic mass unit: If m u = 1 then m g = 1. The sulphate was precipitated by adding excess Barium chloride solution. A compound whose empirical formula is XF3 consists of 65 % F by mass. Protons and neutrons have a mass of 1 atomic mass unit (amu). Example: chlorine occurs in isotope forms Cl-35 (75. Atomic mass is measured via mass spectrometry while molar mass is computed via atomic weight. A homework sheet with 20 RMM to work out, it does require a periodic table. An atom is a primary piece of matter which is made up of protons, neutrons, and electron called subatomic particles. MF from accurate mass (New) This tool allows to generate a list of molecular formula from an accurate mass. The atomic weight of an element is the relative atomic mass of that element. Neutrons, protons, isotopes. Examples: Fe, Au, Co, Br, C, O, N, F. Equivalent Mass. Add up the number of neutrons and protons in a single atom. The formula weight in atomic mass units for the given binary ionic compound is to be determined. Carbon exists as two major isotopes, 12C, and 13C ( 14C exists and has. Under this scheme, a neutral hydrogen atom has a mass of 1. how many neutrons are there in the nucleus of the element? *multiple choice* a) z+4 b) z+2 c) z d) 4 - brainsanswers. Though technically incorrect, the term is also often used to refer to the average atomic mass of all of the isotopes of one element. 0000 atomic mass units. atomic mass (amu) = molar mass (grams). pure substances. Molar mass is the sum of all of the atomic masses in a formula. Calculate the average atomic mass of an element with two naturally occurring isotopes: 85X (72. The relative atomic mass (average atomic mass as you put it) is the weighted average mass of all the isotopes of an element in a given sample, relative to the unified atomic mass unit, which is defined as one twelfth of the mass of a carbon-12 atom in its ground state. Calculate the formula weight of magnesium bromide, MgBr2 Answer: Set up a table similar to the one used in example 1. The term relative atomic mass is sometimes used as a synonym for average atomic mass. The atomic mass of nitrogen is 14. 0027) 2 + (21. Examples: Fe, Au, Co, Br, C, O, N, F. 5 amu? Do not enter units with your answer. Similar Questions. Examples include ionic NaCl and K 2 O and covalent networks such as SiO 2 and C (as diamond or graphite). Relative atomic and formula mass lesson plan template and teaching resources. Molar Mass from Periodic Table Molar mass is the atomic mass expressed in grams. com atomic mass is, atomic mass is…. Atomic mass is the sum of all the protons, neutrons, and electrons in a single atom or molecule. Answer: To find the atomic mass of chlorine, the atomic mass of each isotope is multiplied by the relative abundance (the percent abundance in decimal form) and then the individual masses are added together. Molar mass is the mass (in atomic mass units) of one mole of a of a substance. Each isotope is a different weight. If the relative atomic mass of X is 50. atomic mass of the three isotopes is 24. What is this element? Chromium has the following isotopic masses and relative abundances. Mass, Length, and Volume; Scientific Notation; Significant Figures; Precision and Accuracy; Conversion Factors and Dimensional Analysis; Temperature Measurements; Density: A Derived Unit; Energy: A Derived Unit; Atoms, Ions, and Molecules. Isotope Mass (amu) Percent Abundance (%) Element-35 35 75. Atomic mass gives the mass of atoms while molecular weight gives the mass of molecules. For other isotopes, the isotopic mass usually differs and is usually within 0. If it is not clear from the context that g/mol is the desired answer, go with amu (which means atomic mass unit). 1 23mol NaCl contains 6. 9298 amu and an abundance of 69. how many neutrons are there in the nucleus of the element? *multiple choice* a) z+4 b) z+2 c) z d) 4 - brainsanswers. Average Atomic Mass Practice Problems 1. 992646547 × 10 −23 gram, which is assigned an atomic mass of 12 units. The Periodic Table of Elements ELEMENTS IN SAME COLUMN (GROUP) HAVE SIMILAR CHEMICAL PROPERTIES. Find the average atomic mass for Li if 7. Relative atomic mass' (symbol: A r) or atomic weight is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a given sample to the atomic mass constant. Calculate the average atomic mass of an element with two naturally occurring isotopes: 85X (72. Relative Atomic Mass and Relative Molecular Mass/Relative Formula Mass By international agreement the mass of an atom of carbon-12 is given as 12 unified atomic mass units (u). This information is used to find x in the formula: CuSO4. Convert Atomic Mass Unit to Kilogram. Chapter 1—The Atomic Nature of Matter: Selected Questions for Practice Exam. One atomic mass unit (u) is equal to 1/12 the mass of one atom of carbon-12. For example, one mole of carbon would have a mass of 12. I would appreciate it if someone could help me set up the formula - I will do the work myself (don't want an answer, just help with the. com Chemistry Atomic Number And Mass Number Worksheet Answers What Do from Atomic Mass And Atomic Number Worksheet , source: myfundrazor. Calculate molecular formula, molecular mass / molecular weight, exact mass (monoisotopic mass), elemental analysis and plots the isotopic distribution graph (isotopomers). 34 g of a salt of formula N 2 SO 4 was dissolved in water. Atomic Mass (Numericals), Molecular and Formula Mass. water H2O Therefore Mr for water 16 (2x1) 18. Enter the atomic symbols and percentage masses for each of the elements present and press "calculate" to work out the empirical formula. Components in Dry Air. However, the mass of an electron is so small, it is considered negligible and not included in the calculation. Some text also refers it to formula mass. Substances that cannot be decomposed into two or more simpler substances by chemical means are called a. Relative mass in the average atomic mass of all the isotopes present in percentage while absolute mass is the sum of number of protons and neutrons mass. 02 x 10 23 formula units). 1 Definition of Atomic Mass Constant; 2 Symbol of Atomic Mass Constant; 3 Unit of Atomic Mass Constant; 4 Formula of. none of these 7. Round atomic masses to the tenth of a decimal place. Some Notes about Gram Atomic Mass. The average atomic mass of an element can be found on the periodic table, typically under the elemental symbol. Re: mass times avogadro's numbers = molar mass ?? Mass is an extensive property of matter (extensive means that the property changes depending on how much matter there is). Air is a mixture of several gases, where the two most dominant components in dry air are 21 vol% oxygen and 78 vol% nitrogen. Some Notes about Gram Atomic Mass. Average atomic mass = σ (mass of isotope × relative abundance) The bottom line is that to find the average atomic mass of copper, we insert the information about copper’s isotopes into the formula and solve. The number of grams given on the periodic table represents the mass of one mole of that element. In this video, we calculate the weighted-average atomic mass of an unknown element. Just enter a formula in the box on the left. Molar Mass: Molar mass is the mass in grams of 1 mol of substance (The number of particles in a mole is equal to 6. The atomic mass of carbon is 12 grams per mole. This shared value between molar mass and atomic mass applies to all elements. Beneath each box. because students. Practice Problems: Atomic Mass. 1 Binding energy Two important nuclear propert that we want to study are the nuclear binding energy and the mass of nuclides. Relative Atomic Mass and Relative Molecular Mass/Relative Formula Mass By international agreement the mass of an atom of carbon-12 is given as 12 unified atomic mass units (u). Chemical formula models - International. The molar mass calculation of a substance is complete the following steps (We will use sulfuric acid, H 2 SO 4, as an example):. Formula of Atomic Mass: A = Number of protons + Number of neutrons. The relative atomic mass (A r) of an element is the average mass of the naturally occurring atoms of the element. The number of grams in the molar mass (grams per mole) of any ionic compound. The molecular weight is the sum of the atomic weights of the atoms in the molecule. Calculate the average atomic mass of pennium. water H2O Therefore Mr for water 16 (2x1) 18. Molar mass is the mass (in atomic mass units) of one mole of a of a substance. In this particular case it is not because you had the choice in measuring the reactants involved. water H2O Therefore Mr for water 16 (2x1) 18. It is useful to understand the following in order to be able to explain relative atomic mass: atom, atomic number, element, mass number and isotope. However, 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. Wapstra Nucl. So, the atomic mass is the sum of the masses of protons and neutrons. Typical unit is g/mol. 6) What is the molar mass of MgO? 40. The relative atomic mass (average atomic mass as you put it) is the weighted average mass of all the isotopes of an element in a given sample, relative to the unified atomic mass unit, which is defined as one twelfth of the mass of a carbon-12 atom in its ground state. What Is The Atomic Mass Of X? Question: A Compound Whose Empirical Formula Is XF3 Consists Of 65 % F By Mass. Calculate Relative Atomic Weight (Amu) of an Element. The molecular weight (or molar mass) of a substance is the mass of one mole of the substance, and can be calculated by summarizing the molar masses of all the atoms in the molecule. Calculating relative formula mass. Spectrum Capture utility that can automatically digitize a scanned spectrum and import it for use within MSC. A sample of any element consists of one or more isotopes of that element. The element bromine has two naturally-occurring isotopes. The precision to which a molar mass is known depends on the precision of the atomic masses from which it was calculated, and value of the molar mass constant. Based on carbon -12 standard, the mass of an atom of carbon is 12 units and 1/12th of it comes to be 1 unit. A proton has a mass of 1 AMU A neutron has a mass of 1 AMU An electron has a mass of 0 AMU The Atomic Mass of an element is shown on the period table. Definitions of molecular mass, molecular weight, molar mass and molar weight. 003 amu = 0. The atomic weight is actually a weighted average of all of the naturally occurring isotopes of an element relative to the mass of carbon-12. A water molecule has a mass of 3/2 times that of a carbon atom, therefore it has a relative molecular mass of 18. Molar mass is the mass (in atomic mass units) of one mole of a of a substance. 97 grams per mole, its atomic mass must be 31. Study First 20 Elements, Atomic Number and Mass. none of these 7. Formula Mass- It is the sum of atomic masses of the elements present in one formula unit of a compound. molar mass) is defined as the atomic mass of one mole of an element, molecular compound or ionic compound. biochemtuition. This shared value between molar mass and atomic mass applies to all elements. When compared to protons or neutrons electrons have so much less mass that they don't influence the calculation. A compound containing only element Z and oxygen has the formula ZO3. Relative Atomic Mass The symbol for relative atomic mass is A r. There are 7 neutrons, 7 protons and 7 electrons in a nitrogen atom. The mass of the atom for any element is usually concentrated at its centre in its protons and neutrons. 45 x 10^17 nitrogen atoms, first multiply by the atomic mass, then divide by Avogadro's Number. Difference Between Gram Atomic Mass, Gram Molecular Mass and Formula Mass As we know that all substances are made up of atoms, molecules or formula units. Example: convert 15 u to kg: 15 u = 15 × 1. On this scale. To determine the molecular formula, enter the appropriate value for the molecular mass. g in a 150 person 149 lbs, 15 oz are protons and neutrons while only 1 oz. Please provide values below to convert Atomic mass unit [u] to kilogram [kg], or vice versa. Molar mass is the sum of all of the atomic masses in a formula. 5 u List of Atomic Mass of all the Elements. The mass of water is found by weighing before and after heating. We just used the formula to calculate that. Introduction to Elements and the Periodic Table; The Periodic Table and its Design; Common Groups of Elements; Compounds. 73 x 10^-5 grams. 983 amu) = 24. Formula: The relative atomic mass indicates how many times larger the mass of a given atom is than 1/12 the mass of the 12 C carbon isotope. none of these ANS:B 37. As relative. The atomic weight is basically a measurement of the total number of particles in an atom's nucleus. Carbon exists as two major isotopes, 12C, and 13C ( 14C exists and has. CHEMISTRY COMPUTING FORMULA MASS WORKSHEET Problem Set-up example: Find the formula mass of Ca(NO3)2 Ca: 1 x 40. With simple calculations we get: 1972+163 divided by 3*2= 73. Gram is a metric unit of weight. is the mean mass of its atoms compared to 1/12 th the mass of a carbon-12 atom. The relationship between the charge of an ion and its combining power is continued to be shown to help students understand why chemicals combine with one another. pdf), Text File (. Molar mass is the mass (in atomic mass units) of one mole of a of a substance. Each element's atomic number, name, element symbol, and group and period numbers on the periodic table are given. Molar Mass is the mass of one mole of a substance (6. Atomic weight (symbol: Ar) is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a given source) to 1/12 of the mass of an atom of carbon-12 (known as. This problem can also be reversed, as in having to calculate the isotopic abundances when given the atomic weight and isotopic weights. 0229552894949E+26 atomic mass units, or 6. Just enter a formula in the box on the left. I believe the "a" represents an Atomic mass unit (amu): A unit used to express the mass of an atom equal to exactly one-twelfth the mass of a carbon-12 atom. METHOD 1 To find the formula of magnesium oxide, students will need the mass of the magnesium and the mass of the oxygen. Molecular weight of molecules containing the same atoms like O 2 or N 2 is calculated by multiplying the number of atoms by the atomic weight of the atoms. In this case, find the average of the mass numbers of the isotopes, taking their relative abundances into account. You put a naturally occurring sample of the element into the machine and it sorts out the isotopes of the mass, reporting the AMU mass and the percentage of natural abundance for that mass. Astatine: Atomic mass number given for longest lived isotope. Chemistry 1046. Formula Mass: The formula mass (formula weight) of a molecule is the sum of the atomic weights of the atoms in its empirical formula. The molar mass calculation of a substance is complete the following steps (We will use sulfuric acid, H 2 SO 4, as an example):. Divide the molar mass for the molecular formula by the empirical formula mass. Structure, properties, spectra, suppliers and links for: Oxygen, atomic, Oxygen. Best Answer: So the mass of Magnesium Oxide was 0. H = 1, C = 12, P = 31 etc). Example the relative formula mass of water (H 2 O) is: Relative atomic mass of Hydrogen = 1. This is a very primitive exact mass calculator. Going back to 32 S, we know that because its molar mass is 31. Oxygen has a. Isotope distributions can also be calculated using the Isotopes Calculator in the MS Interpreter tool in the NIST Mass Spectral Database. Award winning periodic table, by relative atomic mass, with user-friendly element data and facts. - The periodic table gives us the atomic number of each element. 34 g of a salt of formula N 2 SO 4 was dissolved in water. is electrons. Calculate the average atomic mass of chromium to two decimal places. Calculate molecular formula, molecular mass / molecular weight, exact mass (monoisotopic mass), elemental analysis and plots the isotopic distribution graph (isotopomers). A mass spectrum of molecular Br 2 shows three peaks with mass numbers of 158 u, 160 u, and 162 u. Find my revision workbooks here: https://www. A compound is 75. The formula for relative atomic mass is; A r = average mass of isotopes of the element Example:. Electrons have nearly 1/2000th of the mass of protons and neutrons, so electrons are typically ignored in calculations involving atomic mass. 3 u P- 2 x 31. It is actually a weighted mass of the elements isotopes (if any) and their relative abundance. How to convert atomic mass units to kilograms [u to kg]: m kg = m u ×1. Atomic Mass Formula Atomic mass is the total of the masses of the electrons, neutrons, and protons in an atom, or in a group of atoms, the average mass. What is the mass (in amu) of a carbon-12 atom? 3. 59 amu, S = 32. The atomic weight of an element is the relative atomic mass of that element. Equivalent Mass. A homework sheet with 20 RMM to work out, it does require a periodic table. Topics also included: Isotopes; formula mass & empirical mass; Atomic & electron structure. Molar mass, symbol M,is the mass of one mole of a substance (chemical element or chemical compound). The molar mass calculation of a substance is complete the following steps (We will use sulfuric acid, H 2 SO 4, as an example):. Atomic #, Mass #, Protons, Neutrons, Electrons Gap-fill exercise. The molar mass for each formula comes from the formula and the periodic table entries. Elemental Formula utility calculates the possible compositions of an ion given its mass. The atomic mass unit is the standard unit used to quantify mass on the atomic scale. So, the atomic mass is the sum of the masses of protons and neutrons. 022 10 formula units The Molar Mass of an Element • The molar mass (M or MM) of an element is the mass in grams of one mole of atoms of the element. 14 or by the individual elements, i. 34 g of a salt of formula N 2 SO 4 was dissolved in water. Atomic Mass Formula Questions: 1. Schematic diagram of a mass spectrometer. Enter the molecular formula of the substance. Atomic weight (symbol: Ar) is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a given source) to 1/12 of the mass of an atom of carbon-12 (known as. Note: Atomic mass unit is a metric unit of weight. Notes on the Atomic Mass of particular elements: Technetium: Atomic mass number given for longest lived isotope. uk/workbooks/shop/ In this video, we take a look at a really important topic in Chemistry. So one mole of O 2 weights : 2 x 16 = 32 grams One mole of carbon dioxide : 12 + (2 x 16) = 44 grams. CHEMISTRY COMPUTING FORMULA MASS WORKSHEET Problem Set-up example: Find the formula mass of Ca(NO3)2 Ca: 1 x 40. So, to find this roughly 12. Most atomic masses are known to a precision of at least one part in ten-thousand, often much better [3] (the atomic mass of lithium is a notable, and serious, [13] exception). Calculate Weighted-Average Atomic Mass. In related terms, another unit of mass often used is Dalton (Da) or unified atomic mass unit (u) when describing atomic masses and molecular masses. We have many methods to determine the equivalent mass of an element, and we will discuss in detail three most popular methods: 1. 9118 amu) and 87X (27. Aluminum is a very common element, third in abundance only to silicon and oxygen. The atomic weight of an element is the relative atomic mass of that element. Concept Review with Key Terms. Add up the number of neutrons and protons in a single atom. 0925) 2 = 20. Award winning periodic table, by relative atomic mass, with user-friendly element data and facts. Topics also included: Isotopes; formula mass & empirical mass; Atomic & electron structure. Go Back to Video List Go to Home page. A compunds whose empirical formula is xf3 consists of 65% f by mass. Before you go on, you should find and read the statement in your copy of the syllabus. Avogadro’s number is also necessary. 1 Laws of Chemical Combination—The basic laws of chemical combination are the law of conservation of mass, the law of constant composition, and the law of multiple proportions. What is the molecular (formula) mass of a compound with the formula M 2 (XO 2) 3 if the atomic mass of M is 31 amu and that of X is 31. The mass of an […]. 70%), 25Mg (10. 01 amu or 14. Title: Relative mass formula, atomic mass, and empirical formula 1 Relative mass formula, atomic mass, and empirical formula 2 Relative formula mass, Mr The relative formula mass of a compound is blatantly the relative atomic masses of all the elements in the compound added together. Chemistry: Average Atomic Mass Worksheet Calculate the average atomic mass for each element based on the natural abundance of its isotopes. This information is used to find x in the formula: CuSO4. PowerPoint covering the basics of atomic and formula mass. As explained earlier, for most elements the relative atomic mass is equal to their mass number. The relative molecular mass is calculated by adding up the relative masses of all of the atoms in a molecule of that substance. 6) What is the molar mass of MgO? 40. Then use the periodic table to identify the element. Calculate the formula weight of magnesium bromide, MgBr2 Answer: Set up a table similar to the one used in example 1. The atomic mass of nitrogen is 14. is the mean mass of its atoms compared to 1/12 th the mass of a carbon-12 atom. 1 mole 12C atoms = 6. There are two isotopes, so we will be adding the contributions of 2 isotopes. Explain the purpose of a mass spectrometer and its general principle of operation. The other isotope, 65Cu, has an abundance of 30. 0160041 amu. The molar mass calculation of a substance is complete the following steps (We will use sulfuric acid, H 2 SO 4, as an example):. The formula weight of an ionic compound is defined in the following way: Formula weight = Mass of 1 mole of formula units Therefore, to get the formula weight of an ionic compound we need simply determine the molar atomic mass of a formula unit. Molecular weight of molecules containing the same atoms like O 2 or N 2 is calculated by multiplying the number of atoms by the atomic weight of the atoms. atomic mass of the three isotopes is 24. The formula weight of a compound is the sum of all the atomic weights of the elements present in the formula of the compound. Molecular mass (molecular weight) is the mass of one molecule of a substance and is expressed in the unified atomic mass units (u). Atomic weight (symbol: Ar) is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a given source) to 1/12 of the mass of an atom of carbon-12 (known as. Examples: Fe, Au, Co, Br, C, O, N, F. Relative Formula Mass. The molar mass is the mass of one mole of matter. because the formula mass is the sum of the atomic masses of the atoms in a chemical compound or element while the atomic mass is the mass of an element's atoms, listed in the periodic table as an. 101 Applied Nuclear Physics (Fall 2006) Lecture 12 (10/25/06) Empirical Binding Energy Formula and Mass Parabolas References: W. b) Chemical formula worksheets - Compounds with polyatomic ions. Scientists refer to the mass of atoms in atomic mass units or amu. Given the formula of a chemical species, the calculator determines the exact mass of a single isotope of that species and the relative abundance of that isotope. For example the absolute mass of carbon is 12. org Worksheets 42 New Basic Atomic Structure Worksheet Hd Wallpaper… Read More. In this particular case it is not because you had the choice in measuring the reactants involved. 01% 14C = neglect Average carbon atomic weight = 12. 0833) the mass of the carbon-12 atom. Best Answer: Formula mass is the mass of a molecule of a covalent compound, CO2, add mass of 1 C and 2 O, 12 +16+16=44grams for a mole, or 44 amu for onemolecule Formulas unit mass is a term used for the mass of a unit cell of an ionic compound that is essentially bound to all the other ions around it. 65 Cu = 64. Relative Formula Mass. The molar mass is the mass of one mole of matter. Metal M has relative atomic mass of 24g/mol. Daniel Rutherford discovered this non-metal element in 1772. 8 hours ago 7. 022 10 formula units The Molar Mass of an Element • The molar mass (M or MM) of an element is the mass in grams of one mole of atoms of the element. Other units are used in SI:tonne (t), electronvolt (eV), and the atomic mass unit (u). 1 u of the mass number. 992646547 × 10 −23 gram, which is assigned an atomic mass of 12 units. b) Calculate the relative atomic mass of N in N 2 SO 4. EXPERT ANSWER. Relative atomic mass = Mass of 1/12 of an atom of carbon-12 Mass of one atom of the element 7. If an input is given then it can easily show the result for the given number. Average atomic mass = f 1 M 1 + f 2 M 2 +… + f n M n where f is the fraction representing the natural abundance of the isotope and M is the mass number (weight) of the isotope. The sum of the masses of these fragments is less than the original mass.