Atomic Structure and Isotopes

Hello and welcome to Introduction to Biology, Biology 105. This is Lecture 2, Chapter 2, Part 2. In this lesson we will cover three main concepts. What is atomic number? What is atomic mass? And what are isotopes? So what is the difference between atomic number and atomic mass? Atomic number, as we went over in the last lesson, It equals the number of protons that an atom has. Each element has a distinct atomic number, and the periodic table shows the atomic number for each atom, and it generally increases as a row from left to right in the periodic table. Atomic mass, on the other hand, is the number of protons and neutrons that an atom has. The number of neutrons can vary from an element. and the variations of this are results in isotopes, which are different forms of the same atom. Isotopes vary only in the number of neutrons they possess. The number of protons and the number of neutrons are the determinants of the element's mass number. So the atomic number is the number of protons. The atomic mass is equal to the number of protons. protons and neutrons and can vary depending on the number of neutrons. So you would have to subtract from the atomic number from the atomic mass to understand how many neutrons an element has. As conceived from the periodic table, every atom of a given element has the same atomic number, which is the number of protons. The atomic number can be used to identify an element. The number of electrons in an atom can vary. Atoms can gain or lose electrons to make ions. We cannot use the number of electrons to identify an atom as a result. A neutral atom has a positive number of protons that is equal to the negative amount of electrons. So the protons and neutrons, if they're the same amount in terms of number, will give you a neutral atom. An atom with a negative charge, such as chlorine, has more protons than electrons, more electrons than protons, more neutrons than protons, or more neutrons than electrons. The correct answer is B, more electrons than protons. So the relationship between atomic mass and atomic number is that the atomic mass is equal Number is the number of protons and does not change for any given atom such as carbon. The atomic number is always the same, which is 6. Whereas the atomic mass can change because that depends on the number of protons and neutrons. And here you can have carbon-12 or carbon-13. And these are various two isotopes of carbon. So isotopes form an element. for example, isotopes are different forms of an element that have the same number of protons but a different number of neutrons. Isotopes form from different number of neutrons and thus the mass of these different isotopes are different, but the atomic number is the same as conceding from this example here that carbon... always has an atomic number of 6, which means that it contains 6 protons and 6 neutrons and 6 electrons and therefore has a mass of 12. But its other isotope, which has an atomic number of 6 still, but has an atomic mass of 14 because of the 6 protons and the 8 neutrons. These two alternative forms of carbon are called isotopes. and they do have different properties. Isotopes can come from different atoms. Here, for example, you have one extra neutron here, and here you have two. So the different numbers of neutrons make the different mass numbers. So what is a radioactive isotope? A radioactive isotope is one in which the nucleus decl... decay spontaneously and this causes radiation from decay. which can damage cellular molecules and pose serious health risks. So an example here is that of beta decay. Because isotopes are not always stable, some isotopes may emit neutrons, protons, and electrons in order to attain a more stable atomic configuration, a lower level of potential energy. These are called radioactive isotopes or radioisotopes. The radioactive decay... such as we can see in this slide from the carbon 14 of a neutron and the loss of a proton because of cosmic rays. This is a continuous process so that carbon 14 is always being created. Now initially, a living organism incorporates carbon 14 as fixed carbon dioxide through a process of photosynthesis. The relative amount of carbon 14 in the body is equal to the concentration of carbon 14 in the atmosphere as a result. when the organism dies and no longer is ingesting the carbon-14. So the ratio between carbon-14 and carbon-12 will decline. In this process, carbon-14 decays gradually to nitrogen-14 by a process called beta decay. Electrons or positron emissions happen, and the decay emits energy, and it's a very slow process. So about... After approximately 5,730 years, half of the starting concentration of carbon-14 will convert back to nitrogen-14. Recall this time it takes for half of the original concentration of the isotope to decay back to its more stable form as its half-life. Carbon-14 is used by scientists to date formerly living objects such as old bones or wood. And this is called radioactive dating. The radioisotopes, which are the isotopes that emit the neutrons, protons, and electrons, are used to date natural things such as bones, fossils, and old objects. So by comparing the ratio of carbon-14 concentration and the object's amount of carbon-14 in the atmosphere, scientists can determine the amount of appropriate isotope that is not yet decade On the basis of this amount, we can calculate the age of the material with accuracy if it's not much older than 50,000 years old. Other elements have isotopes which have different half-lives, for example, such as potassium-40, which has a half-life of about 1.25 billion years. And uranium-235, which has a half-life of about 700 million years through the use of radioactive dating. Scientists can study. the age of fossils and other means of extinct organisms in order to understand how organisms have evolved over earlier species. So in summary, atoms have three sub-particles, protons, neutrons, and electrons. Protons have a positive charge, neutrons are neutral and have a zero charge, and electrons have a negative charge and orbit around the nucleus. Isotopes are different forms of atoms and they have different mass numbers due to the different number of neutrons that the isotope has. Isotopes have the same number of electrons and the same number of protons as other atoms of the element.

So what is the difference between atomic number and atomic mass? Atomic number, as we went over in the last lesson, It equals the number of protons that an atom has. Each element has a distinct atomic number, and the periodic table shows the atomic number for each atom, and it generally increases as a row from left to right in the periodic table. Atomic mass, on the other hand, is the number of protons and neutrons that an atom has. The number of neutrons can vary from an element.

and the variations of this are results in isotopes, which are different forms of the same atom. Isotopes vary only in the number of neutrons they possess. The number of protons and the number of neutrons are the determinants of the element's mass number. So the atomic number is the number of protons.

The atomic mass is equal to the number of protons. protons and neutrons and can vary depending on the number of neutrons. So you would have to subtract from the atomic number from the atomic mass to understand how many neutrons an element has. As conceived from the periodic table, every atom of a given element has the same atomic number, which is the number of protons.

The atomic number can be used to identify an element. The number of electrons in an atom can vary. Atoms can gain or lose electrons to make ions.

We cannot use the number of electrons to identify an atom as a result. A neutral atom has a positive number of protons that is equal to the negative amount of electrons. So the protons and neutrons, if they're the same amount in terms of number, will give you a neutral atom.

An atom with a negative charge, such as chlorine, has more protons than electrons, more electrons than protons, more neutrons than protons, or more neutrons than electrons. The correct answer is B, more electrons than protons. So the relationship between atomic mass and atomic number is that the atomic mass is equal Number is the number of protons and does not change for any given atom such as carbon.

The atomic number is always the same, which is 6. Whereas the atomic mass can change because that depends on the number of protons and neutrons. And here you can have carbon-12 or carbon-13. And these are various two isotopes of carbon. So isotopes form an element. for example, isotopes are different forms of an element that have the same number of protons but a different number of neutrons.

Isotopes form from different number of neutrons and thus the mass of these different isotopes are different, but the atomic number is the same as conceding from this example here that carbon... always has an atomic number of 6, which means that it contains 6 protons and 6 neutrons and 6 electrons and therefore has a mass of 12. But its other isotope, which has an atomic number of 6 still, but has an atomic mass of 14 because of the 6 protons and the 8 neutrons. These two alternative forms of carbon are called isotopes.

and they do have different properties. Isotopes can come from different atoms. Here, for example, you have one extra neutron here, and here you have two.

So the different numbers of neutrons make the different mass numbers. So what is a radioactive isotope? A radioactive isotope is one in which the nucleus decl...

decay spontaneously and this causes radiation from decay. which can damage cellular molecules and pose serious health risks. So an example here is that of beta decay. Because isotopes are not always stable, some isotopes may emit neutrons, protons, and electrons in order to attain a more stable atomic configuration, a lower level of potential energy.

These are called radioactive isotopes or radioisotopes. The radioactive decay... such as we can see in this slide from the carbon 14 of a neutron and the loss of a proton because of cosmic rays. This is a continuous process so that carbon 14 is always being created.

Now initially, a living organism incorporates carbon 14 as fixed carbon dioxide through a process of photosynthesis. The relative amount of carbon 14 in the body is equal to the concentration of carbon 14 in the atmosphere as a result. when the organism dies and no longer is ingesting the carbon-14. So the ratio between carbon-14 and carbon-12 will decline.

In this process, carbon-14 decays gradually to nitrogen-14 by a process called beta decay. Electrons or positron emissions happen, and the decay emits energy, and it's a very slow process. So about...

After approximately 5,730 years, half of the starting concentration of carbon-14 will convert back to nitrogen-14. Recall this time it takes for half of the original concentration of the isotope to decay back to its more stable form as its half-life. Carbon-14 is used by scientists to date formerly living objects such as old bones or wood. And this is called radioactive dating.

The radioisotopes, which are the isotopes that emit the neutrons, protons, and electrons, are used to date natural things such as bones, fossils, and old objects. So by comparing the ratio of carbon-14 concentration and the object's amount of carbon-14 in the atmosphere, scientists can determine the amount of appropriate isotope that is not yet decade On the basis of this amount, we can calculate the age of the material with accuracy if it's not much older than 50,000 years old. Other elements have isotopes which have different half-lives, for example, such as potassium-40, which has a half-life of about 1.25 billion years.

And uranium-235, which has a half-life of about 700 million years through the use of radioactive dating. Scientists can study. the age of fossils and other means of extinct organisms in order to understand how organisms have evolved over earlier species.

So in summary, atoms have three sub-particles, protons, neutrons, and electrons. Protons have a positive charge, neutrons are neutral and have a zero charge, and electrons have a negative charge and orbit around the nucleus. Isotopes are different forms of atoms and they have different mass numbers due to the different number of neutrons that the isotope has.

Isotopes have the same number of electrons and the same number of protons as other atoms of the element.

Transcript for:Atomic Structure and Isotopes

Transcript for:
Atomic Structure and Isotopes