Atomic Theory and Experiments Quiz

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Questions and Answers

Which type of radiation can be stopped with a thin metal sheet?

  • Alpha particles (correct)
  • Beta particles (correct)
  • Gamma rays
  • All of the above

Gamma rays are not affected by a magnetic field because they carry no charge.

True (A)

What is the last element with any stable nuclei?

Lead

An alpha particle is actually a nucleus of a __________.

<p>helium atom</p> Signup and view all the answers

Who is known as the father of atomic theory?

<p>John Dalton (D)</p> Signup and view all the answers

In which branch of medicine are radioisotopes used?

<p>Nuclear medicine (A)</p> Signup and view all the answers

The process in which a free neutron causes the nucleus of an atom to split is called __________.

<p>a chain reaction</p> Signup and view all the answers

Atoms can be created or destroyed during a chemical reaction.

<p>False (B)</p> Signup and view all the answers

What evidence did J.J. Thomson use to discover electrons?

<p>Cathode rays</p> Signup and view all the answers

Match the following types of nuclear reactions with their descriptions:

<p>Fission = Splitting of a nucleus into two daughter nuclei Nucleosynthesis = Process occurring in the sun and stars Beta decay = Losing a neutron during decay Transuranium elements = Synthetic elements formed by bombardment reactions</p> Signup and view all the answers

The charge of an alpha particle is ______.

<p>positive</p> Signup and view all the answers

The half-life of a given isotope can be altered by heat and pressure.

<p>False (B)</p> Signup and view all the answers

What is the ratio of atoms in a water molecule (H2O)?

<p>1:2 (A)</p> Signup and view all the answers

Match the following isotopes with their corresponding abundance and mass:

<p>Boron-10 = 19.9%, 10.013 u Boron-11 = 80.1%, 11.009 u</p> Signup and view all the answers

The nucleus of an atom is much larger than the entire atom.

<p>False (B)</p> Signup and view all the answers

What element is likely to have 90 protons and a good number of neutrons for stability?

<p>Thorium</p> Signup and view all the answers

What happens to a small atom with the same number of protons and neutrons?

<p>It is found in nature as it is stable. (A)</p> Signup and view all the answers

Two different atoms of carbon have the same atomic mass.

<p>False (B)</p> Signup and view all the answers

What is an alpha particle composed of?

<p>Two protons and two neutrons</p> Signup and view all the answers

The process through which unstable atoms become stable by emitting particles is called ________.

<p>radioactive decay</p> Signup and view all the answers

Match the terms with their definitions related to radioactive decay:

<p>Alpha Particle = Positively charged particle made of two protons and two neutrons Beta Particle = Electron released causing a neutron to change into a proton Gamma Rays = High-energy electromagnetic radiation Half-life = Time for half the atoms in a radioactive sample to decay</p> Signup and view all the answers

Which type of decay results in another element with an atomic number two less?

<p>Alpha decay (B)</p> Signup and view all the answers

Gamma rays can be stopped by a piece of paper.

<p>False (B)</p> Signup and view all the answers

Marie Curie discovered radioactivity and won two Nobel Prizes for her work on ________ and ________.

<p>Polonium and Radium</p> Signup and view all the answers

What particle did Lord Ernest Rutherford discover?

<p>Alpha particles (C)</p> Signup and view all the answers

An isotope has the same number of neutrons but a different number of protons.

<p>False (B)</p> Signup and view all the answers

What is the mass number of an element calculated from?

<p>The mass number is the sum of the number of protons and neutrons.</p> Signup and view all the answers

The process by which an electron falls into the nucleus is known as __________.

<p>K-electron capture</p> Signup and view all the answers

Match the type of radioactive decay to its description:

<p>Alpha Particle Emission = Decreases atomic number by 2, mass number by 4 Beta Particle Emission = Increases atomic number by 1, mass number remains the same Positron Emission = Decreases atomic number by 1, mass number remains the same Gamma Radiation = No change in atomic or mass numbers</p> Signup and view all the answers

Which statement about beta particle emission is true?

<p>It produces an electron (A)</p> Signup and view all the answers

Name one application of nuclear medicine.

<p>Cancer therapy</p> Signup and view all the answers

Gamma radiation consists of low-energy photons.

<p>False (B)</p> Signup and view all the answers

Flashcards

Atomic Theory: Dalton's Contribution

John Dalton's atomic theory proposed that atoms are indivisible and indestructible, and that atoms of the same element are identical. Chemical reactions involve rearranging atoms, not creating or destroying them.

Atomic Structure: J.J. Thomson's Discovery

J.J. Thomson discovered negatively charged particles called electrons using cathode ray experiments. This showed that atoms are not indivisible, but contain subatomic particles.

Gold Foil Experiment

Rutherford's gold foil experiment showed that most alpha particles passed through a thin gold foil, but a few bounced back. This indicated a dense, positively charged nucleus at the atom's center.

Nuclear Charge

The nucleus of an atom is positively charged. This positive charge is what repels positively charged alpha particles in Rutherford's experiment.

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Atomic Nucleus

The central, dense part of an atom containing protons and neutrons. Almost all the atom's mass is located here.

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Law of Conservation of Mass

In a chemical reaction, the total mass of the reactants equals the total mass of the products.

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Isotope Abundance

The relative percentage of each isotope of an element. Average atomic mass is calculated from isotopes' mass and their abundance.

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Band of Stability

The region of stability in the neutron-vs-proton graph (stability map), an element is stable if it lies within the region, elements outside the region are unstable.

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Alpha particle

A positively charged particle that is essentially the nucleus of a helium atom.

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Beta particle

A fast-moving electron emitted from the nucleus of an atom during radioactive decay.

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Gamma ray

High-energy electromagnetic radiation emitted during radioactive decay. It has no charge and high energy.

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Radioactive decay

The process where an unstable atomic nucleus loses energy and becomes more stable by emitting radiation.

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Nuclear fission

A nuclear reaction where a heavy nucleus splits into two or more smaller nuclei.

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Half-life

The time it takes for half of a radioactive substance to decay.

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Radioisotope

An isotope that is radioactive and emits radiation.

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Nuclear medicine

Branch of medicine that uses radioisotopes for diagnosing and treating diseases.

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Radioactive Isotope

An unstable nucleus that changes over time by emitting particles and/or energy.

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Alpha Decay

A radioactive element breaks down, forming a new nucleus.

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Transmutation

The changing of one atom into another during radioactive decay.

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Alpha Particle Emission

An ordinary helium nucleus is emitted from a radioactive nucleus.

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Beta Particle Emission

A radioactive process that emits an electron, converting a neutron to a proton.

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Gamma Radiation Emission

High-energy photons (light) emitted during radioactive decay, doesn't change mass or atomic numbers.

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Positron Emission

A positron (positive electron) is emitted, converting a proton to a neutron.

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K-Electron Capture

An electron is absorbed by the nucleus turning a proton into a neutron.

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Isotopes

Atoms of the same element with different numbers of neutrons.

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Nuclear Bombardment

A process where a nucleus is hit by particles/atoms to make a new atom, efficient at lower atomic numbers.

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Radioactive Isotopes in Medicine

Used in cancer therapy and disease diagnosis.

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Study Notes

Atomic Theory

  • Father of Atomic Theory: John Dalton
  • Atomos: Indivisible (meaning of the term spoken by Democritus)
  • Atoms: Cannot be created or destroyed during chemical changes
  • Law of Conservation of Mass: No detectable change in mass during chemical reactions
  • Law of Definite Proportions: Same proportions of elements by mass in compounds
  • Ratio of atoms in Hâ‚‚O: 1:2
  • J.J. Thomson's Discovery: Electrons (negatively charged) evidenced by cathode ray experiments (opposites attract)

Alpha Particles and Gold Foil Experiment

  • Alpha Charge: Positive
  • Gold Foil Experiment Findings: Most alpha particles passed through; some deflected (bounced back) suggesting a small, dense nucleus
  • Rutherford's Conclusion: Nucleus is positively charged; almost all the mass of the atom is concentrated in the nucleus. Nucleus is significantly smaller than the entire atom

Atomic Abundance

  • Boron-10 Abundance: 19.9% and Isotope Mass: 10.013 u
  • Boron-11 Abundance: 80.1% and Isotope Mass: 11.009 u
  • Average Atomic Mass Calculation: 10.811 amu (calculated by adding the product of abundance and isotope mass for each isotope)

Nuclear Ionizing Radiation

Band of Stability

  • Element with 90 protons: Ideal number of neutrons for stability is 142. The element would be Thorium.

Other Important Concepts

  • Large Atoms (more than 40 protons): Less likely to exist naturally given that the ratio of protons and neutrons would not be 1:1
  • Small Atoms (less than 20 protons): Likely to exist naturally, in a 1:1 ratio, stable in nature.
  • Two Different Types of Carbon Atoms: Different atomic masses because of varying neutron numbers, despite having the same number of protons.
  • Vocabulary: Terms including Alpha particle, Beta particle, Radioactive, half-life, Radioactive decay, gamma rays
  • Radioactive Decay Processes: Alpha decay (emitting helium nuclei), beta decay (electron emission changing a neutron to a proton), gamma decay (high-energy electromagnetic radiation).
  • Transmutation: Transforming one type of atom into another during radioactive decay.
  • Tracer: Radioisotope used to track movement in a body.
  • Parts of a Nuclear Reactor: Fuel, moderator, control rods
  • Structure of Elements: Elements are composed of atoms, and compounds are made of atoms.
  • Isotopes: Atoms of the same element with the same number of protons but different number of neutrons.
  • Isobars: Atoms with the same mass number (total protons and neutrons) but different atomic numbers.
  • Modes of Radioactive Decay: Alpha, Beta, Gamma
  • Positron Emission: Positron (positive electron) emission changing from proton to neutron.
  • K-electron Capture: Electron falls into the nucleus converting proton to neutron.
  • Nuclear Bombardment: Utilizing atomic particles (like alpha particles) to create new elements
  • Nuclear Medicine: Use of radioactive isotopes to diagnose and treat diseases.

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