{"id":4663,"date":"2017-06-09T19:38:11","date_gmt":"2017-06-09T19:38:11","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/hccs-waymakerbiology1\/?post_type=chapter&#038;p=4663"},"modified":"2024-04-25T23:24:54","modified_gmt":"2024-04-25T23:24:54","slug":"isotopes","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/chapter\/isotopes\/","title":{"raw":"Isotopes","rendered":"Isotopes"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Define the term isotope<\/li>\r\n<\/ul>\r\n<\/div>\r\n<b>Isotopes<\/b> are different forms of the same element that have the same number of protons, but a different number of neutrons. Some elements, such as carbon, potassium, and uranium, have naturally occurring isotopes. Carbon-12, the most common isotope of carbon, contains six protons and six neutrons. Therefore, it has a mass number of 12 (six protons and six neutrons) and an atomic number of 6 (which makes it carbon). Carbon-14 contains six protons and eight neutrons. Therefore, it has a mass number of 14 (six protons and eight neutrons) and an atomic number of 6, meaning it is still the element carbon. These two alternate forms of carbon are isotopes. Some isotopes are unstable and will lose protons, other subatomic particles, or energy to form more stable elements. These are called <strong>radioactive isotopes<\/strong> or <strong>radioisotopes<\/strong>.\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Evolution in Action: Carbon Dating<\/h3>\r\n[caption id=\"attachment_4666\" align=\"alignright\" width=\"350\"]<img class=\"wp-image-4666\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1648\/2017\/06\/09193506\/CarbonDating-300x240.jpeg\" alt=\"Photograph shows scientists digging pygmy mammoth skeleton fossils from the ground.\" width=\"350\" height=\"280\" \/> Figure 1. The age of remains that contain carbon and are less than about 50,000 years old, such as this pygmy mammoth, can be determined using carbon dating.[\/caption]\r\n\r\nCarbon-14 (<sup>14<\/sup>C) is a naturally occurring radioisotope that is created in the atmosphere by cosmic rays. This is a continuous process, so more <sup>14<\/sup>C is always being created. As a living organism develops, the relative level of <sup>14<\/sup>C in its body is equal to the concentration of <sup>14<\/sup>C in the atmosphere. When an organism dies, it is no longer ingesting <sup>14<\/sup>C, so the ratio will decline. <sup>14<\/sup>C decays to <sup>14<\/sup>N by a process called beta decay; it gives off energy in this slow process.\r\n\r\nAfter approximately 5,730 years, only one-half of the starting concentration of <sup>14<\/sup>C will have been converted to <sup>14<\/sup>N. The time it takes for half of the original concentration of an isotope to decay to its more stable form is called its half-life. Because the half-life of <sup>14<\/sup>C is long, it is used to age formerly living objects, such as fossils. Using the ratio of the <sup>14<\/sup>C concentration found in an object to the amount of <sup>14<\/sup>C detected in the atmosphere, the amount of the isotope that has not yet decayed can be determined. Based on this amount, the age of the fossil can be calculated to about 50,000 years (Figure 1). Isotopes with longer half-lives, such as potassium-40, are used to calculate the ages of older fossils. Through the use of carbon dating, scientists can reconstruct the ecology and biogeography of organisms living within the past 50,000 years.\r\n\r\n<\/div>\r\n\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/7da36949-59cb-482f-97cb-282ca46c9205\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Define the term isotope<\/li>\n<\/ul>\n<\/div>\n<p><b>Isotopes<\/b> are different forms of the same element that have the same number of protons, but a different number of neutrons. Some elements, such as carbon, potassium, and uranium, have naturally occurring isotopes. Carbon-12, the most common isotope of carbon, contains six protons and six neutrons. Therefore, it has a mass number of 12 (six protons and six neutrons) and an atomic number of 6 (which makes it carbon). Carbon-14 contains six protons and eight neutrons. Therefore, it has a mass number of 14 (six protons and eight neutrons) and an atomic number of 6, meaning it is still the element carbon. These two alternate forms of carbon are isotopes. Some isotopes are unstable and will lose protons, other subatomic particles, or energy to form more stable elements. These are called <strong>radioactive isotopes<\/strong> or <strong>radioisotopes<\/strong>.<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Evolution in Action: Carbon Dating<\/h3>\n<div id=\"attachment_4666\" style=\"width: 360px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-4666\" class=\"wp-image-4666\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1648\/2017\/06\/09193506\/CarbonDating-300x240.jpeg\" alt=\"Photograph shows scientists digging pygmy mammoth skeleton fossils from the ground.\" width=\"350\" height=\"280\" \/><\/p>\n<p id=\"caption-attachment-4666\" class=\"wp-caption-text\">Figure 1. The age of remains that contain carbon and are less than about 50,000 years old, such as this pygmy mammoth, can be determined using carbon dating.<\/p>\n<\/div>\n<p>Carbon-14 (<sup>14<\/sup>C) is a naturally occurring radioisotope that is created in the atmosphere by cosmic rays. This is a continuous process, so more <sup>14<\/sup>C is always being created. As a living organism develops, the relative level of <sup>14<\/sup>C in its body is equal to the concentration of <sup>14<\/sup>C in the atmosphere. When an organism dies, it is no longer ingesting <sup>14<\/sup>C, so the ratio will decline. <sup>14<\/sup>C decays to <sup>14<\/sup>N by a process called beta decay; it gives off energy in this slow process.<\/p>\n<p>After approximately 5,730 years, only one-half of the starting concentration of <sup>14<\/sup>C will have been converted to <sup>14<\/sup>N. The time it takes for half of the original concentration of an isotope to decay to its more stable form is called its half-life. Because the half-life of <sup>14<\/sup>C is long, it is used to age formerly living objects, such as fossils. Using the ratio of the <sup>14<\/sup>C concentration found in an object to the amount of <sup>14<\/sup>C detected in the atmosphere, the amount of the isotope that has not yet decayed can be determined. Based on this amount, the age of the fossil can be calculated to about 50,000 years (Figure 1). Isotopes with longer half-lives, such as potassium-40, are used to calculate the ages of older fossils. Through the use of carbon dating, scientists can reconstruct the ecology and biogeography of organisms living within the past 50,000 years.<\/p>\n<\/div>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_7da36949-59cb-482f-97cb-282ca46c9205\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/7da36949-59cb-482f-97cb-282ca46c9205?iframe_resize_id=assessment_practice_id_7da36949-59cb-482f-97cb-282ca46c9205\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-4663\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Biology. <strong>Provided by<\/strong>: OpenStax CNX. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\">http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">Public domain content<\/div><ul class=\"citation-list\"><li>Carbon Dating. <strong>Authored by<\/strong>: Bill Faulkner\/NPS. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/www.nps.gov\/chis\/learn\/historyculture\/pygmymammoth.htm\">https:\/\/www.nps.gov\/chis\/learn\/historyculture\/pygmymammoth.htm<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/about\/pdm\">Public Domain: No Known Copyright<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":18798,"menu_order":6,"template":"","meta":{"_candela_citation":"[{\"type\":\"pd\",\"description\":\"Carbon Dating\",\"author\":\"Bill Faulkner\/NPS\",\"organization\":\"\",\"url\":\"https:\/\/www.nps.gov\/chis\/learn\/historyculture\/pygmymammoth.htm\",\"project\":\"\",\"license\":\"pd\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Biology\",\"author\":\"\",\"organization\":\"OpenStax CNX\",\"url\":\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\"}]","CANDELA_OUTCOMES_GUID":"658d1dbb-2452-444e-9469-671f8c16b4ec, 4a260a31-cbef-4d21-8115-aea75cf198d8","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4663","chapter","type-chapter","status-publish","hentry"],"part":43,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/chapters\/4663","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/wp\/v2\/users\/18798"}],"version-history":[{"count":12,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/chapters\/4663\/revisions"}],"predecessor-version":[{"id":6674,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/chapters\/4663\/revisions\/6674"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/parts\/43"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/chapters\/4663\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/wp\/v2\/media?parent=4663"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/pressbooks\/v2\/chapter-type?post=4663"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/wp\/v2\/contributor?post=4663"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology1\/wp-json\/wp\/v2\/license?post=4663"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}