Log in Ini-Oluwa 6 months agoPosted 6 months ago. Direct link to Ini-Oluwa's post “Do all elements have isot...” Do all elements have isotopes? • (20 votes) FreeRadical 6 months agoPosted 6 months ago. Direct link to FreeRadical's post “Yes, all elements have is...” Yes, all elements have isotopes! But some are exceedingly rare. (33 votes) kcyrillejt 4 months agoPosted 4 months ago. Direct link to kcyrillejt's post “why do isotopes exist?? w...” why do isotopes exist?? what is the reason for different numbers of neutrons • (8 votes) Kennedy 4 months agoPosted 4 months ago. Direct link to Kennedy's post “That's a great question. ...” That's a great question. Isotopes exist because of the very way elements are created. These are natural processes that involve primarily (but aren't limited to) nuclear reactions. You have probably heard people like Neal deGrasse Tyson, Brian Cox or Brian Greene talk about stars and nebulae, and how they are stellar nurseries. Let's take Carbon as an example: in the core of stars (like our sun), there's this process called nuclear fusion, in which the pressure is so ridiculously great, hydrogen nuclei (protons) are forced to combine and form helium nuclei. As the temperature and pressure increase, helium nuclei can then fuse to form carbon nuclei (I am making this simple to get the message across, but you can google "triple-alpha process" for more information). Three helium nuclei then combine to form a carbon-12 nucleus. Here we have our first isotope. During this process, some of the carbon-12 nuclei can capture additional neutrons to form carbon-13. This whole process involding nuclear reactions to create carbon istopes is called stellar nucleosynthesis (again, you can google it for more info). Carbon-14, on the other hand, is formed in the Earth's atmosphere. Out there in the universe, there are high-energy cosmic rays originating from sources even outside our solar system. These cosmic rays collide with nitrogen-14 nuclei found in our atmosphere, and this results in the production of carbon-14. This process is ongoing and maintains a constant level of carbon-14 in the atmosphere. Because of that, the relative abundance of isotopes can vary. Carbon-12 is the most abundant isotope of carbon, accounting for about 98.9% of natural carbon. Carbon-13 makes up about 1.1% of natural carbon, and carbon-14 is present in trace amounts, but it is still detectable and useful for various applications, such as radiocarbon dating. So, again, to answer your question, isotopes (like carbon-12, carbon-13, and carbon-14) are formed through processes such as stellar nucleosynthesis in stars and interactions between cosmic rays and atmospheric nuclei. These processes lead to variations in the number of neutrons in the carbon nuclei, resulting in different isotopes of the element, and therefore in different properties also (such as their rates of radioactive decay). (21 votes) tracefarthing 5 months agoPosted 5 months ago. Direct link to tracefarthing's post “If an isotope is an atom ...” If an isotope is an atom with a different number of neutrons then electrons, how is carbon 12 an isotope if it has 6 protons and 6 neutrons? • (5 votes) ATKal1 5 months agoPosted 5 months ago. Direct link to ATKal1's post “Carbon-12 is an isotope b...” Carbon-12 is an isotope because it is one of the possible forms of carbon atoms. An isotope is defined by the number of protons and neutrons in its nucleus, not by the number of electrons. Carbon atoms have 6 protons, but they can have different numbers of neutrons, such as 6, 7, or 8. These are called carbon-12, carbon-13, and carbon-14, respectively. They are all isotopes of carbon, but they have different masses and properties. Carbon-12 is the most abundant and stable isotope of carbon, accounting for 98.9% of element carbon on Earth (15 votes) Karthi 6 months agoPosted 6 months ago. Direct link to Karthi's post “To find a mass number we ...” To find a mass number we need to know the number of protons right?But we don't know the # of protons.How should we find # of protons. • (3 votes) wenrui 6 months agoPosted 6 months ago. Direct link to wenrui's post “the atomic number is the ...” the atomic number is the # of protons (13 votes) balenzin 2 months agoPosted 2 months ago. Direct link to balenzin's post “Why does proton define th...” Why does proton define the chemiscal element? why could not be the neutron or eletron? • (4 votes) muhammadkhankk945 2 months agoPosted 2 months ago. Direct link to muhammadkhankk945's post “The proton is crucial in ...” The proton is crucial in defining chemical elements because it determines the identity of an atom. An atom's identity is determined by the number of protons in its nucleus, which is called the atomic number. For example, all atoms with one proton in their nucleus are hydrogen atoms, those with two protons are helium atoms, and so forth. This unique number of protons distinguishes one element from another in the periodic table. While both neutrons and electrons are important components of an atom, they do not define the element itself. Neutrons contribute to the mass of the atom and help stabilize the nucleus, but they do not affect the atom's chemical properties. Electrons are involved in chemical reactions and bonding, but their number can vary within an element's atoms without changing its identity. In summary, the proton defines the chemical element because it determines the atomic number, which is the fundamental characteristic that distinguishes one element from another. hope it helped (3 votes) penny.g.caldwell 3 months agoPosted 3 months ago. Direct link to penny.g.caldwell's post “at 1:42 where did the sec...” at • (3 votes) muhammadkhankk945 2 months agoPosted 2 months ago. Direct link to muhammadkhankk945's post “she is telling the number...” she is telling the number of protons in carbon hope you understood her meaning and found that she was talking about protons in carbon (3 votes) Holli McDonald 3 months agoPosted 3 months ago. Direct link to Holli McDonald's post “What is the rarest isotop...” What is the rarest isotope? • (3 votes) penny.g.caldwell 3 months agoPosted 3 months ago. Direct link to penny.g.caldwell's post “Tantalum (Ta-180)” Tantalum (Ta-180) (3 votes) ermieball 2 months agoPosted 2 months ago. Direct link to ermieball's post “What's the purpose of the...” What's the purpose of the hyphen in X-A? • (3 votes) TheReal3A 2 months agoPosted 2 months ago. Direct link to TheReal3A's post “I guess to make it clear ...” I guess to make it clear that it's an isotope. (4 votes) Melinda 3 months agoPosted 3 months ago. Direct link to Melinda's post “Do elements have many ato...” Do elements have many atoms? • (3 votes) ΣЖΞΜPLΛRΨ DNΛ 2 months agoPosted 2 months ago. Direct link to ΣЖΞΜPLΛRΨ DNΛ's post “It depends greatly. If yo...” It depends greatly. If you get a very small amount of the element, then it will obviously have rather few atoms. But if you get a larger amount of the element, then there will be more atoms. (2 votes) Nesi a month agoPosted a month ago. Direct link to Nesi's post “is their an element that ...” is their an element that doesnt have isotopes • (2 votes) Infrared a month agoPosted a month ago. Direct link to Infrared's post “All elements have isotope...” All elements have isotopes, although some have only one that is found in nature. All the fluorine (element 9) in found in nature is fluorine-19. (3 votes)Want to join the conversation?
1:42 2:56
To illustrate, an isotope of Hydrogen with 1 proton and 1 neutron is shown as H-2 (the atomic mass is 1+1 = 2). Rather than H2, which can be confused with the chemical formula for hydrogen gas - H₂.
Video transcript
- [Instructor] Every element is defined by the number of protons in its atoms, which is called its atomic number. So for example, every atomof potassium has 19 protons and every atom of cobalt has 27 protons. But what about neutrons? Well, an element doesn'talways have the same number of neutrons in its atoms. Atoms of the same element withdifferent numbers of neutrons are called isotopes. Because isotopes of an element have different numbers of neutrons, those isotopes also have different masses. Remember, most of the mass of an atom comes from the protons andneutrons in its nucleus. In fact, the sum of the number of protons and neutrons in an atomis called its mass number. We can write this in the formof an equation as follows, mass number equals the number of protons, plus the number of neutrons. Next, let's dive into isotope notation, or how we represent isotopes in writing. When describing different isotopes, you'll often see this notation where X is the chemical symbol, which is an abbreviationof the element's name, A is the mass number, thenumber of protons plus neutrons, and Z is the atomic number,the number of protons. Let's practice writing out the notation for different isotopes. We'll start with carbon, which has an atomic number of 6. In nature, carbon is mainly composed of two different isotopes. One of these isotopes has 6 neutrons and the other isotope has 7 neutrons. Let's start with the isotope that has 6 protons and 6 neutrons. With that information, we know that the mass number must be 12, which is the sum of theprotons and neutrons. So the notation for this isotope of carbon would look like this. We have the chemical symbol C with the mass number 12written at its top-left, and the atomic number 6written at its bottom-left. But for the isotope with6 protons and 7 neutrons, the mass number would be 6 plus 7, or 13. So the notation for the carbonisotope would be as follows. Here, we have the chemical symbol C with the mass number 13written at its top-left, and the atomic number 6written at its bottom-left. Notice that the chemicalsymbol and atomic number share the same information,the identity of the element, and are the same for both isotopes, but the mass number isdifferent for each isotope depending on the number of neutrons. Another notation that is used for isotopes is the chemical symbolor the element's name, symbolized by X, followed by a hyphen, and the mass number,symbolized by A, so X-A. Let's return to ourcarbon isotopes example. For the carbon isotope thathas 6 protons and 6 neutrons, we write that as C-12 or carbon-12. For the carbon isotope with6 protons and 7 neutrons, we write that as C-13 or carbon-13. Let's wrap up this videowith a quick recap. We know that elements are defined by the number of protons in their atoms, but atoms of the same element can have different numbers of neutrons. These are called isotopes. Because isotopes havedifferent numbers of neutrons, they also have different mass numbers, which are the sum ofthe protons and neutrons in each isotope's atom. An atom's mass number can bedescribed by the equation, mass number equals the number of protons, plus the number of neutrons. And lastly, we can describe isotopes using a couple of different notations, which are shown below.
