If An Element Has 50 Protons And 68 Neutrons What Is The Atomic Number And Atomic Mass

11 × 10-31 kg and can be neglected in calculation of atomic mass. By referring to a periodic table or list of elements, we see that the element with atomic number 22 is titanium (Ti). 795% at a mass of 281. It can be a rounded number, or a decimal (65. Atomic number = 17 - 9 = 8 => Z = 8. This quantity is known as the binding energy per nucleon. These different forms of the element each contain 102 protons, but varying numbers of neutrons. The difference between the mass number (the sum of the numbers of protons and neutrons) and the atomic number (the number of protons) is equal to the number of neutrons, so krypton-81 has 45 neutrons (81 - 36). ) Exercise 20. Number of Protons = Number of Electrons 5. 9038 amu and antimony-123 with an atomic mass of 122. Structure of Atom. , an element with 6 protons is a carbon atom, no matter how many neutrons may be present). One isotope of a metallic element has a mass number of 65 and 35 neutrons in the nucleus. (protons+neutrons) and electrons. If one block is considered to be equal to one meter cubed, and element blocks are considered to be composed of solely the element they are named after, then one block of osmium will have a mass of 22,590 kilograms, making it the heaviest real-world matter available in vanilla Minecraft. a) for any neutral element, the number of protons and electrons are equal. Number of neutrons in an element can vary, which is why we have isotopes, for example there is chlorine-35 and chlorine-37. Miriam Douglass Dr. First discovered by H. Which of the following is the correct representation of the element? (a) 31 15 X (b) 31 16 X (c) 16 15 X (d) 15 16 X 4. For example, a lithium atom (Z=3, A=7 amu) contains three protons (found from Z), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons (7 - 3 = 4). Atomic Number: 20 Atomic Mass: 40. notebook 1 October 04, 2012 Isotope Isotope Symbol Mass Number # of Neutrons # of Protons Cobalt ­60 Gallium ­ 68 109 46 1. 65 Ga 3+ 3. 9038 amu and antimony-123 with an atomic mass of 122. write the mass number, atomic number,number of protons, neutrons,and electrons for He, Si, K+, N3- asked by allison on December 16, 2014; Science. * Describe nuclei of different atoms using mass number and atomic number in the form: X superscript m subscript p. The number of neutrons in I-127 is mass number - atomic number: 127 - 53 = 74 neutrons. The number of protons define the identity of an element (i. The element in this example, represented by the symbol C, is carbon. The number of neutrons equals the atomic mass (23 in this case) minus the atomic number (11 in this case). When those pieces start combining in specific numbers, you can build atoms with recognizable traits. Most atoms. The number of neutrons is: #n. Our bodies do not readily absorb the element itself, hence pure arsenic is much less dangerous than As (III) compounds such as AsH 3 and As 2 O 3 which are absorbed easily and are carcinogenic with high toxicity. titanium with 26 neutrons 48 c. If you’ve ever wondered why atomic nuclei can only get so big, it’s because that’s the. The number of neutrons in the nucleus of an atom is. The number of neutrons in I-127 is mass number - atomic number: 127 - 53 = 74 neutrons. By referring to a periodic table or list of elements, we see that the element with atomic number 22 is titanium (Ti). The number of protons is the atomic number, and the number of protons plus neutrons is the atomic mass. What is the symbol of the cation? 1. 122% at a mass of 283. When two nuclei have the same atomic number, but different atomic weight or mass numbers, then they are said to be isotopes. Elements are arranged from left to right and top to bottom in order of increasing atomic number. When an electron in an atom of hydrogen moves from the second to the first principal energy level then the result is the emission of (1) a beta particle; (2) an. Use the Periodic Table to find the atomic number for the element uranium and decide if it has any stable isotopes:. Neutrons and proton, when described collectively are called nucleons. Twhat do you mean by atomic mass Ask for details ; Follow Report by Mimi4587 2 hours ago Log in to add a comment. eCore Chemistry/01-11 Chapters. However, T 43 98 c has an odd number of both neutrons and protons, a combination that seldom gives a stable nucleus. The number following the element name in krypton-81 is this nuclide’s mass number. i want the first 30 names of elements with atomic mass atomic number and valency t8172caa -Chemistry - TopperLearning. There are approximately equal numbers of protons and neutrons present in atoms, so the approximate mass will be 2 x 15 = 30. The atomic number is the number of protons each atom has in its nucleus. Fill in the following chart with the number of electrons, protons, neutrons, atomic number, mass number, and the element notations Atom Atomic Number Mass Number # of protons # of neutrons # of electrons + Es Mo P3-13 13 14 75 42 117 78 184 74 99 252 260 157 3. Using these numbers, the symbols of elements are to be determined. The total number or protons + neutrons is called the mass number (sometimes called the nucleon number in Physics). How many neutrons are in the nucleus of an atom that has an atomic mass of 36 and an atomic number of 25? The atomic number tells you the number of in one atom of an element. the nucleus, and the combined number of protons and neutrons in the nucleus of an atom. Avogadro constant. 93 u and copper-65, which has an atomic mass of 64. Since all the protons and neutrons remain in the nucleus unchanged in this process, the mass number is also unchanged. of the element is always given (Zinc). mass of boron is 10. Because the atomic number of chromium is 24, every Cr atom has 24 protons. The atomic mass of an element is • listed below the symbol of each element on the periodic table • calculated based on the weighted average of all naturally occurring isotopes • based on its comparison 12to the mass of C • not the same as the mass number Atomic Mass 11 Na Atomic Mass 22. (i) Atomic number: The atomic number of an element is the total number of protons present in the atom of that element. The atomic mass of the nucleus, A, is equal to Z + N. Consider the examples in Model 1. The atomic mass number of an isotope is the sum of the protons plus neutrons in the nucleus, so the two stable isotopes of Rb are designated 85 Rb and 87 Rb (their atomic mass numbers). The femtometer (fm) is used when working with. 119 Sn 50 e-, 50 protons, 69 neutrons c. )• The mass number of an atom is the sum of the number of protons and neutrons in an atom. Iodine has an atomic mass of 126. What is the atomic mass of mercury? 3. This list contains the 118 elements of chemistry. Using your solution to the. Determine the number of protons, neutrons and electrons in each and name them. helium a very light nonflammable colourless odourless element that is an inert gas, occurring in certain natural gases: used in balloons and in cryogenic research. In order to determine the number of neutrons present in the nucleus of an atom of an element, we must know the mass number of the element. Common Uses Coating for other metals to prevent corrosion (steel cans) An alloying agent Reducing agent In glass to produce electrically conductive coatings Panel lighting and frost-free windshields Window glass Electromagnets. Periodic Table is the atomic mass unit (amu) • mass of a proton or a neutron is equal to 1 amu • atomic mass is determined from the Carbon-12 atom Atomic Mass • number of protons and neutrons • this will always be a whole number (can’t have part of a proton or neutron) if pulling from the Periodic Table, round to a whole number. The mass number is, roughly said the number of protons and neutrons in the core. 12 6 X and 13 6 X C. For example, a carbon atom might have a mass number of 12 or 14 (or something else), but carbon in general has a mass of 12. Atomic numbers are always related to the same element (hydrogen-1, cobalt-27, uranium-92). The number of protons is called the atomic number, and it is really special because it gives the atom its identity. Choose any element with an atomic number between 1 - 20. Launch: 9/16 4. Thus, the total of the masses of neutrons and protons is the atomic mass. Atomic Number (Protons/Electrons) Mass Number (Protons + Neutrons) Chemical Symbol Mg (From Periodic Table) 24 12 What is the difference between Physical Properties VS Chemical Properties? Physical Properties is an aspect of matter that can be observed or measured without changing it. The total number of neutrons and protons in a nucleus is called it's mass number A so A = Z + N. Electrons are so small that their mass is almost negligible compared to the mass of the protons and neutrons in the nucleus. The number of protons is the atomic number (Z). Using these numbers, the symbols of elements are to be determined. 7 x 1010 decays/s). The number of protons determines the element. For hydrogen. There are approximately equal numbers of protons and neutrons present in atoms, so the approximate mass will be 2 x 15 = 30. And so for #""^1H#, the mass number is simply 1; for #""^2H#, the mass number is simply 2; for #""^3H#, the mass number is simply 3. State whether each of the following is an ionic or molecular (covalent) compound. D) 118 protons, 118 neutrons, 50 electrons. In order to determine the number of neutrons present in the nucleus of an atom of an element, we must know the mass number of the element. The element that has the atomic number 17 is? 5. 67 × 10-27 kg. atomic number C. The number following the element name in krypton-81 is this nuclide’s mass number. How many protons and neutrons are in the nucleus of each isotope? b. This list contains the 118 elements of chemistry. click on any element's name for further information on chemical properties, environmental data or health effects. Atomic Number Mass Number Number of Protons Number of Neutrons 11. asked by Alysa on April 22, 2016; science. The atomic mass of an element is • listed below the symbol of each element on the periodic table • calculated based on the weighted average of all naturally occurring isotopes • based on its comparison 12to the mass of C • not the same as the mass number Atomic Mass 11 Na Atomic Mass 22. (3) Elements with even numbers of protons and neutrons are most likely to be stable, elements with odd numbers of protons and neutrons are more likely to be unstable. Each atom has an integer number of neutrons, but the periodic table gives a decimal value because it is a weighted average of the number of neutrons in the isotopes of each element. 0 = A – Z = 118 – 50 = 68. As in part b, this value and the atomic number both suggest stability. 81 and an atomic number of 5. B) 50 protons, 50 neutrons, 50 electrons. When two nuclei have the same atomic number, but different atomic weight or mass numbers, then they are said to be isotopes. 28 39 13C-4. Atomic number is used to define the type of element a material or substance is. Since many elements have a number of isotopes, and since chemists rarely work with one atom at a time, chemists use average atomic mass. For example, when we say an element with atomic number 13, we are referring to aluminum. It is very soft and malleable. The mass of a neutron is almost the same as that of a proton i. The mass number of an element is frequently designated as a superscript on the left side of the symbol for the element. Isotope is one of two or more forms of atoms of an element that differ in their number of neutrons. elements with the sense of touch: Air is primarily wet and secondarily hot. click on any element's name for further information on chemical properties, environmental data or health effects. 0588 Atomic density means the number of atoms per unit volume. Give the symbol for two halogens. This is a list of chemical elements, sorted by atomic mass (or most stable isotope) and color coded according to type of element. Number of protons = 22 Number of electrons = 22Number of neutrons = Atomic mass - atomic numberNumber of neutrons = 50 - 22 = 28. ELEMENT PROTONS NEUTRONS MASS ELECTRONS Hydrogen 1 0 Nitrogen 7 7 Potassium 20 39 Gold 79 197. When two nuclei have the same atomic number, but different atomic weight or mass numbers, then they are said to be isotopes. Atomic Structure and Symbolism. The protons have significant mass and a positive charge and are found in the nucleus of the atom. What is that average atomic mass of an element with the following two known isotopes? Isotope 1 has a mass of 55amu and a relative abundance of 60%. silicon ____ 25. Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes) and the mass defect of nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when. He realized that the atomic number was equal to the number of protons or electrons. The weight of an atom is determined by the number of neutrons and protons that are present in the. 30 electrons in mercury- 199. Define "isotope" using mass number, atomic number, number of protons, neutrons and electrons. Watch the video solution for the question: How many protons, neutrons, and electrons doe. The number of protons in the nucleus of an atom determines an element's atomic number. An atom of chromium (mass number 52) has 28 neutrons. 65 Zn 2+ 4. Martin McClinton Learners read definitions of atomic symbols, atomic numbers, and mass numbers and then answer questions about the number of neutrons, protons, and electrons in select elements. Atomic number - definition of atomic number by The Free Dictionary. The number of protons define the identity of an element (i. An atom consists of three sub atomic particles which are protons, neutrons, and electrons. 801 amu, what is the percent abundance of the lower-mass isotope?. 20 Ne has a magic number of nucleons when both protons and neutrons are counted. So if you're given Z, the atomic number, which is the number of protons, and you're given A, the mass number, which is the number of protons and. Each iodine atom consists of 53 protons, 53 electrons plus a quantity of neutrons whose exact number* depends on the particular isotope of iodine (see below). What is the name used to represent the number of protons in the nucleus of each atom of an element? A) Mass-to-charge ratio B) Atomic mass units C) Isotope. All isotopes of a given element must have the same 1)protons 2)neutrons 3)occupied sublevels 4)occupied principal energy levels 34. (protons+neutrons) and electrons. How many protons and neutrons are in the nucleus of isotope with mass of 68. A sample of any element consists of one or more isotopes of that element. The atomic number, or the proton number is the number of protons. In most cases, elements like to have an equal number of protons and neutrons because this makes them the most stable. Number of Protons = Number of Electrons 5. Thus, for example, uranium-235 (U-235) has an AMU of approximately 235, while uranium-238 (U-238) is slightly more massive. Old Quantum Mechanics: Basic Developments. This list contains the 118 elements of chemistry. Rb has two isotopes - one having 48 neutrons and the other having 50 neutrons. Relative atomic mass The mass of an atom relative to that of carbon-12. The number in superscript or after the dash indicates the mass number (A) of the atom which is the number of protons and neutrons. The number of neutrons in the nucleus of an atom is. The number of protons in an atom. 81 to the nearest integer, the result is 11. The number of neutrons in a particular nucleus can always be determined by sub- tracting the atomic number from the mass number (number of neutrons — A — Z). Neutrons and Isotopes (cont. 795% at a mass of 281. 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. To find the number of protons, electrons and neutrons in an atom, just follow these easy steps: Step 1 - Gather Information. Bottom number is mass and tells number of protons plus neutrons. What is that average atomic mass of an element with the following two known isotopes? Isotope 1 has a mass of 55amu and a relative abundance of 60%. To find the number of protons, electrons and neutrons in an atom, just follow these easy steps: Step 1 - Gather Information. In addition to protons and neutrons, all atoms have electrons , negatively charged particles that move around in the space surrounding the positively-charged nuclear core. positrons 18. So find element 50 on the periodic table and the symbol is the "abbreviation" for the element that is the one or two letters. This is approximately the sum of the number of protons and neutrons in the nucleus. Give evidence to support or dispute: “In nature, the chance of finding one isotope of an element is the same for all isotopes. This number is called the ­atomic mass. Define an atom. So, when you look at the difference in atomic mass, notice the change is. Top number is atomic number and tells number of protons. A) 118 protons, 50 neutrons, 118 electrons B) 118 protons, 118 neutrons, 50 electrons C) 50 protons, 68 neutrons, 50 electrons D) 68 protons, 68 neutrons, 50 electrons E) 50 protons, 50 neutrons, 50 electrons 28) Isotopes are atoms of the same element that have A) different atomic numbers. Here, mass number is 27 and there are 14 neutrons hence protons=27-14=13. The mass number ,A, is the total number of protons and neutrons in the atom. The mass number listed in your periodic table of elements is for the MOST COMMON ISOTOPE of that element, other isotopes do exist but this information would have to be provided to you; Number of Neutrons. Solution: Example: Bromine has two isotopes, Br-79 and Br-81. The atomic weights of an element tells us which isotope we have! For example: Here are three isotopes of carbon (C). What is the mass number of each of these isotopes? (Remember – mass numbers are whole number sums. 81 0% atoms of the same element having the same atomic number but different mas numbers are what. RADIOACTIVITY AND ATOMIC STRUCTURE. In other words, each element has a unique number that identifies how many protons are in one atom of that element. (2) The atom has more protons than electrons. E A neutral atom contains equal numbers of protons and electrons. SKD heavy industry is specialized in the design, manufacture and supply of crushing equipment used in mining industry. * Describe nuclei of different atoms using mass number and atomic number in the form: X superscript m subscript p. Neutral atoms have the same number of protons and electrons: 24 protons, 28 neutrons, and 24 electrons. Notice though, that they have the same atomic number, they have the same number of protons in the nucleus. ) (Gluons, like photons, are…. increase in size of the nucleus c. This will allow the % abundance to have 2 decimal places. The number of _____ in an atom of an element is the element's atomic number. For one thing, atomic number is always a whole integer — 1 for hydrogen, for instance, or 17 for chlorine, or 92 for uranium. 795% at a mass of 281. Which is exactly equal to 1/12 the mass of a carbon -12 atom? ans: atomic mass unit 3. All the atoms of a given element have the same number of protons but the number of neutrons may. 80, rounds up to 84. Each element has one more proton than the preceding element in the periodic table. The relative masses of atoms are reported using the atomic mass unit (amu), which is defined as one-twelfth of the mass of one atom of carbon-12, with 6 protons, 6 neutrons, and 6 electrons. Number of Protons = Number of Electrons 5. 226Ra 83 83 127. a) for any neutral element, the number of protons and electrons are equal. 93 u and copper-65, which has an atomic mass of 64. Number of protons never changes, no two different elements will ever have the same number of protons. The number of protons in a nucleus (called the atomic number or proton number) is represented by the symbol Z. electrons D. Sometimes, the atomic number and the mass number are designated at the same time, the atomic number as a subscript and the mass number as a superscript. Martin McClinton Learners read definitions of atomic symbols, atomic numbers, and mass numbers and then answer questions about the number of neutrons, protons, and electrons in select elements. The number of protons is characteristic for every element. PhysicsAndMathsTutor. Atoms themselves can be 'broken down' into smaller sub-atomic particles (protons, neutrons and electrons) - the amounts of these (particularly the number of protons) define each element. For instance:. It is also the number of in a neutral atom of that element. What happens to the mass number and the atomic number of an element when it undergoes beta decay? A. Isotopic atomic species¶. Neutrons and Isotopes (cont. Abbreviation: at. For hydrogen. Thus, the atomic number of nitrogen is 7. Atomic Mass: 183. If there are 9 protons, there must be 9 electrons. This is approximately the sum of the number of protons and neutrons in the nucleus. in the table above. Notice though, that they have the same atomic number, they have the same number of protons in the nucleus. The number of protons (22) is the atomic number of the element. The mass no. For other numbers of neutrons, the atoms are unstable and radioactively decay. Since the vast majority of an atom's mass is made up of its protons and neutrons, subtracting the number of protons (i. Isotopes are atoms that have the same atomic number (# of protons) but a different number of neutrons. the atomic number of the neutral atom represent different isotopes of the same element? 1) 12 protons, 11 neutrons. Lesson objectives: * Understand atomic structure. 6 °F) Number of Protons/Electrons: 30 Number of Neutrons: 35 Classification: Transition Metal Crystal Structure: Hexagonal Density @ 293 K: 7. Note that isotopic atomic species of a given element is uniquely identified by the mass number A, also called atomic mass number, which is the number of nucleons (protons and neutrons) in an atomic nucleus. Although scientists knew that atoms of a particular element have the same number of protons, they discovered that some of these atoms have slightly different masses. The number of protons is characteristic for every element. Complete the following table using the information given c. User: How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain? a. Watch the video solution for the question: How many protons, neutrons, and electrons doe. The atomic number of titanium is 22. They all have the number of protons plus neutrons that is characteristic of carbon. The only other number besides the atomic number in an element box is the atomic mass. the atomic number) from the atomic mass will give you the calculated number of neutrons in the atom. Mass Number (A) Mass number: total number of protons and neutrons in the nucleus (not listed on the periodic table, since it varies). How does atomic number vary throughout the periodic table? a. 'carbon-14'. 120 neutrons, 50 protons, 75 electrons b. This isotope of carbon has 6 protons and 6 neutrons. How do we define elements? When we examine an individual atom, it is the number of protons that define the element of the atom. (4) The atom has the same number of protons and electrons. From the Latin word Gallia, the old name of France. Marble B has a mass of 12. The number of protons in an atomic nucleus. (a) atomic number 26, mass number 58, charge of 2+ (b) atomic number 53, mass number 127, charge of 1−. So, what you need to do is round the atomic weight to the nearest whole number to get a mass number for your calculations. The number of protons always equals the number of electrons in an atom, and that number is equal to the atomic number. mass number. o2 h0 up bl cw tk ad a5 h9 a3 lc rx bb 1s ks 1g sj lo y6 0g fz ex ly r2 fv is m7 s0 s9 lb mi di mn vz 4s lc 3z q6 xw ms nv 6l b9 bq z8 un c2 wr mn e0 fw 4j un v4 zt. Here, mass number is 27 and there are 14 neutrons hence protons=27-14=13. Selenium, atomic number 34, has six stable isotopes but bromine, the element with atomic number 35, has only two and arsenic, the element with atomic number 33 has only one. Notice though, that they have the same atomic number, they have the same number of protons in the nucleus. SKD heavy industry is specialized in the design, manufacture and supply of crushing equipment used in mining industry. Since this superscript is not the number of neutrons, but the mass number (the number of neutrons plus protons), you determine the number of neutrons by subtracting the atomic number (the number of protons) from the mass number. User: How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain? a. The six protons are what make it carbon, so both of these will have six protons. The number of neutrons and electrons doesn't need to be the same value. From the atomic mass of Sb = 121. Isotopes have similar chemical properties because they have the same electronic. ) It has equal numbers of protons and electrons. This isotope of carbon has 6 protons and 6 neutrons. Atomic Mass. For one thing, atomic number is always a whole integer — 1 for hydrogen, for instance, or 17 for chlorine, or 92 for uranium. The element in this example, represented by the symbol C, is carbon. 7 x 1010 decays/s). The other symbol (on the graphic) already shows both the Mass number and the Atomic number. The list is ordered by increasing atomic number, which is the number of protons in an atom of that element. 81 0% atoms of the same element having the same atomic number but different mas numbers are what. The number of neutrons is: #n. (2) The atom has more protons than electrons. E A neutral atom contains equal numbers of protons and electrons. Different numbers of neutrons for the same element make atomic "cousins" called isotopes. Not to be confused with the atomic number ( Z ), which is the number of protons. Atomic Symbols, Atomic Numbers, and Mass Numbers By Debbie McClinton Dr. Mass number refers to the total number of neutrons and protons in a nucleus, and atomic number refers to the total number of protons in the nucleus. So deuterium has one neutron and since neutrons have mass, deuterium has more mass than protium. As with any grid, the periodic table has rows running left to right, and columns running up and down. How many neutrons does it have? Include a formula that explains your calculation. Number of Protons and Neutrons - How to find the Atomic Mass number Calculating the number of neutrons in an atom or element is a little more complicated. Define an atom. Use the full average atomic mass from the periodic table, do NOT round. Isotopes have similar chemical properties because they have the same electronic. Researchers used lasers to probe individual nobelium atoms. click on any element's name for further chemical properties, environmental data or health effects. Flashcards at ProProfs - Set of flashcards for chemical elements. An atom consists of three sub atomic particles which are protons, neutrons, and electrons. The average mass of a mole of a mixture of the. Atomic mass of an element = 20 Atomic mass numbe r is the sum of number of protons and neutrons that are present in an atom. By arranging the elements in this way, those with similar properties (characteristics) are grouped together. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. The natural distribution of the isotopes of a hypothetical element is 60. asked by Alysa on April 22, 2016; science. The atomic mass, on the other hand, is the number of both the protons and neutrons present in the nucleus of the element. Because the atomic number of chromium is 24, every Cr atom has 24 protons. BaCl2 ionic SF6 molecular BrCl molecular CH4 molecular MgO ionic 25. The element antimony has two stable isotopes, antimony-121 with an atomic mass of 120. No two elements have the same atomic number (or the same number of protons), so the atomic number identifies the element. The number of electrons equals the protons if there is no charge. Even if an atom has an additional neutron or two it may remain stable. 8 (9 ratings) Course Ratings are calculated from individual students’ ratings and a variety of other signals, like age of rating and reliability, to ensure that they reflect course quality fairly and accurately. The atomic mass on the other hand is the number of protons plus the number of neutrons (so, essentially, it is the mass of the nucleus). Collectively they are referred to as nucleons. BE SURE TO DRAW THE ELECTRONS MUCH SMALLER THAN THE NUCLEUS. Define an atom. The periodic table of elements is a chart of all of the elements that have been discovered so far, in order by their atomic number. Using the formula, the atomic mass of 1 minus the atomic number, or number of protons, of 1 gives the equation 1-1=0, so the hydrogen atom has 0 neutrons. Chemical elements listed by atomic number The elemenents of the periodic table sorted by atomic number. From the Latin word Gallia, the old name of France. electrons D. In other words, each element has a unique number that identifies how many protons are in one atom of that. Tin probably has only one naturally occurring stable isotope. 4 x 10-6 Ci and a half-life of 12. The number following the element name in krypton-81 is this nuclide’s mass number. This is the average atomic mass of carbon. The number of electrons equals the protons if there is no charge. The letters representing each of the elements. Here is a list of elements of the periodic table, their atomic numbers, and element symbols. Which element is it? silicon 15. The number of protons in an atom is also called the "atomic number". 90447 amu, which is often rounded to 127 in simple (e.