WGU INC1\/C451 Module 4: Universe
Describe the general structure of an atom. – \u2714\u2714The atom is a basic unit of matter consisting of a
dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic
nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in
the case of hydrogen-1, which is the only stable nuclide with no neutrons). The electrons of an
atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can
remain bound to each other, forming a molecule. An atom containing an equal number of protons
and electrons is electrically neutral; otherwise it has a positive or negative charge and is an ion.
An atom is classified according to the number of protons and neutrons in its nucleus: the number
of protons determines the chemical element, and the number of neutrons determines the isotope
of the element.
What makes an atom radioactive? – \u2714\u2714Atoms with unstable nuclei are said to be radioactive.
Sooner or later, they break down and eject energetic particles and emit electromagnetic radiation.
Explain the difference between an alpha particle, a beta particle, and a gamma ray. – \u2714\u2714An
alpha particle is the combination of two protons and two neutrons (in other words, it is the
nucleus of the helium atom, atomic number 2). Alpha particles are relatively easy to shield
against because of their relatively large size and their double positive charge (+2) whileW A beta
particle is an electron ejected from a nucleus. Once ejected, it is indistinguishable from an
electron in a cathode ray or in an electrical circuit, or from an electron orbiting the atomic
nucleus. The difference is that a beta particle originates inside the nucleus?from a neutron. As we<\/p>\n\n\n\n
shall soon see, the neutron becomes a proton once it loses the electron that has become a beta
particle. A beta particle is normally faster than an alpha particle, and it carries only a single
negative charge (-1 ) and Gamma rays are the high-frequency electromagnetic radiation emitted
by radioactive elements. Like photons of visible light, a gamma ray is pure energy. The amount
of energy in a gamma ray, however, is much greater per photon than in visible light, ultraviolet
light, or even X-rays. Because they have no mass or electric charge, and because of their high
energies, gamma rays are able to penetrate through most materials.
List sources of radiation. – \u2714\u2714Cosmic radiation, Ground , Air (radon-222), Human tissues (K40; Ra-226), Smoking , Medical procedures, Diagnostic X rays , Nuclear medicine , TV tubes,
other consumer products , Weapons-test fallout , Coal-burning power plants, Commercial
nuclear power plants
What is the difference between a rad (radiation absorbed dose) and a rem (roentgen equivalent
mass)? – \u2714\u2714Radiation dosage is commonly measured in rads (radiation absorbed dose), a unit of
absorbed energy. One rad is equal to 0.01 joule of radiant energy absorbed per kilogram of tissue
while rem is a unit of measurement for radiation dosage based on potential damage
Explain the strong nuclear force and the electric force in an atom. – \u2714\u2714Strong nuclear force in
an atom is an attraction of positively charged protons in the nucleus that remain clumped
together. It acts between all nucleons. This force is very strong, but only over extremely short
distances (about 10?15 meters, the diameter of a typical atomic nucleus). While Repulsive
electrical interactions (electric force), on the other hand, have a relatively long range.<\/p>\n\n\n\n
Why must the strong nuclear force be present in the nucleus of an atom? – \u2714\u2714While two protons
repel each other by the electric force, they also attract each other by the strong nuclear force.
Both of these forces act simultaneously. So long as the attractive strong nuclear force is stronger
than the repulsive electric force, the protons will remain together. Under conditions in which the
electric force overcomes the strong nuclear force, however, the protons fly apart from each other.
Neutrons serve as?nuclear cement? holding the atomic nucleus together. Protons attract both
protons and neutrons by the strong nuclear force.
How does the size of an atom affect the strength of the strong nuclear force and the electric
force? – \u2714\u2714A large nucleus is not as stable as a small one. In a helium nucleus, for example,
each of the two protons feels the repulsive effect of the other. In a uranium nucleus, each proton
feels the repulsive effects of the other 91 protons! The nucleus is unstable. We see that there is a
limit to the size of the atomic nucleus. It is for this reason that all nuclei having more than 82
protons are radioactive. For large nuclei, more neutrons than protons are needed. Because the
strong nuclear force diminishes rapidly over distance, nucleons must be practically touching in
order for the strong nuclear force to be effective. Nucleons on opposite sides of a large atomic
nucleus are not attracted to one another. The electric force, however, diminishes very little across
the diameter of a large nucleus, and so it wins out over the strong nuclear force. To compensate
for the near absence of the strong nuclear 24 force across the diameter of the nucleus, large
nuclei have more neutrons than protons.<\/p>\n","protected":false},"excerpt":{"rendered":"
WGU INC1\/C451 Module 4: UniverseDescribe the general structure of an atom. – \u2714\u2714The atom is a basic unit of matter consisting of adense, central nucleus surrounded by a cloud of negatively charged electrons. The atomicnucleus contains a mix of positively charged protons and electrically neutral neutrons (except inthe case of hydrogen-1, which is the only […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-114471","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/114471","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=114471"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/114471\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=114471"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=114471"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=114471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}