Nucleus and Radioactivity SAQ

Atoms are mostly empty space with a dense positive core called the nucleus.

The nucleus is made of tiny solid protons and neutrons packed together tightly.

Most alpha particles passed through and some were deflected up to angles of 180°.

<p>Each element has a unique emission line spectrum.</p> Signup and view all the answers

<p>The change in energy levels determines the frequency of the emitted light.</p> Signup and view all the answers

<p>The energy of a charged particle in an electric field is equal to the product of Planck's constant and the frequency of the emitted light.</p> Signup and view all the answers

<p>The physical phenomenon is the emission of light as the element transitions from a higher energy level to a lower energy level.</p> Signup and view all the answers

<p>Electrons given energy jump to high energy state, then fall back to lower energy state, emitting a fixed 'quantum' of energy.</p> Signup and view all the answers

<p>Lasers function by providing a 'lasing medium' with energy, putting all atoms on the same energy level, then they emit light of the same wavelength when they drop from this energy level.</p> Signup and view all the answers

<p>Atomic number (Z) is the number of protons in the nucleus, while mass number (A) is the total number of protons and neutrons in the nucleus.</p> Signup and view all the answers

<p>Radioactivity is the spontaneous emission of radiation due to the natural disintegration of an unstable nucleus.</p> Signup and view all the answers

<p>Isotopes are atoms of the same atomic number but different atomic mass.</p> Signup and view all the answers

<p>The 'lasing medium' is provided with energy to bring all atoms to the same energy level, allowing them to emit light of the same wavelength when they drop back down.</p> Signup and view all the answers

<p>The atomic number is the number of protons in the nucleus of an atom, and it defines the identity of an element.</p> Signup and view all the answers

<p>Isotopes of the same element have the same atomic number but different mass numbers due to varying numbers of neutrons in the nucleus.</p> Signup and view all the answers

<p>Radioactivity is the spontaneous emission of radiation due to the natural disintegration of an unstable nucleus.</p> Signup and view all the answers

<p>Alpha radiation has a + charge, while beta radiation has a - charge.</p> Signup and view all the answers

<p>A radioisotope is an unstable isotope of an element that decays spontaneously, emitting radiation. It is used in medical imaging and carbon dating.</p> Signup and view all the answers

<p>Alpha and gamma radiation are deflected in electric and magnetic fields.</p> Signup and view all the answers

<p>Alpha radiation has a + charge, beta radiation has a - charge, and gamma radiation has no charge.</p> Signup and view all the answers

<p>The principle is that radiation ionizes a gas contained in a tube, and the number of ionizations can be counted. It is used to detect nuclear radiation.</p> Signup and view all the answers

<p>Radioactive decay is the breakup of a nucleus with the release of radiation. Types of radiation emitted include alpha, beta, and gamma radiation.</p> Signup and view all the answers

<p>Alpha emission is the emission of a helium nucleus, while beta emission is the emission of an electron.</p> Signup and view all the answers

<p>Gamma emission is the emission of high-energy photons from an unstable nucleus. The characteristic is that it is a high-energy form of electromagnetic radiation.</p> Signup and view all the answers

<p>Ionization is the process by which radiation interacts with a gas, producing ions that can be counted to detect radiation.</p> Signup and view all the answers

<p>The activity of a radioactive source is directly proportional to the number of undecayed nuclei, and is given by the equation A = λN.</p> Signup and view all the answers

<p>The unit of measurement for the activity of a radioactive source is the becquerel (Bq), and it represents one decay per second.</p> Signup and view all the answers

<p>The half-life of a radioactive isotope is inversely proportional to the decay constant, and is given by the equation T½ = ln2/λ.</p> Signup and view all the answers

<p>The half-life of a radioactive isotope represents the time taken for half of the nuclei in a given sample to decay, and it is a characteristic property of the isotope.</p> Signup and view all the answers

<p>The activity of a radioactive source is a measure of the rate of emissions from the source, while the half-life of a radioactive isotope is a measure of the time taken for half of the nuclei in a sample to decay.</p> Signup and view all the answers

<p>Nuclear fission is the splitting of a large nucleus into two smaller nuclei, releasing energy, while nuclear fusion is the combining of two small nuclei to form a single larger nucleus, also releasing energy.</p> Signup and view all the answers

<p>The equation E=mc^2 shows that a small amount of mass (m) can be converted into a large amount of energy (E), and vice versa, which is a fundamental principle behind nuclear reactions.</p> Signup and view all the answers

<p>Neutrons are emitted during nuclear fission, which helps to sustain the reaction by colliding with other nuclei and causing them to split.</p> Signup and view all the answers

<p>The underlying principle is that the resulting nuclei have a lower mass than the initial nuclei, with the mass difference being converted into energy according to the equation E=mc^2.</p> Signup and view all the answers

<p>Nuclear fission releases energy by breaking down a heavy nucleus into lighter ones, while nuclear fusion releases energy by combining light nuclei into a heavier one.</p> Signup and view all the answers