Chemistry Quiz: Electron Energy Levels
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Questions and Answers

What occurs when an electron absorbs enough energy to promote itself to a higher energy level?

  • Chemical bonding
  • Electromagnetic radiation
  • Ionisation
  • Excitation (correct)

What is the result of ionisation in atoms?

  • The atom gains additional electrons
  • The atom's outer electron level becomes filled
  • The atom remains neutral
  • The atom loses an electron, resulting in a positive charge (correct)

What property controls the chemical behavior of an element?

  • Electron configuration (correct)
  • Atomic mass
  • Electromagnetic radiation frequency
  • Ionisation energy

What happens to an atom after it returns from an excited state to its ground state?

<p>It emits energy in some form (A)</p> Signup and view all the answers

Which of the following statements about atoms with filled outer electron levels is true?

<p>They are chemically inert (A)</p> Signup and view all the answers

What is considered the fundamental building block of matter?

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

Which scientist is known for developing the first Atomic Theory of Matter?

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

What did John Joseph Thomson discover in 1897?

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

What charge did Eugen Goldstein conclude that canal rays possess?

<p>Positive charge (D)</p> Signup and view all the answers

Which model of the atom is commonly used to explain phenomena in radiography?

<p>Planetary model (A)</p> Signup and view all the answers

What does the Greek word from which 'atom' is derived mean?

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

What is the primary focus of atomic and subatomic structure theories?

<p>Explaining matter composition (C)</p> Signup and view all the answers

What characteristic did John Dalton say all atoms of a given element share?

<p>Same atomic weight (B)</p> Signup and view all the answers

What does the atomic number (Z) represent in an atom?

<p>Number of protons in the nucleus (C)</p> Signup and view all the answers

What is the atomic mass number (A) of an atom?

<p>Sum of protons and neutrons (C)</p> Signup and view all the answers

Which of the following statements about nuclides is true?

<p>Isotopes of an element have the same number of protons. (A)</p> Signup and view all the answers

How are isotopes of carbon represented?

<p>By changing the number of neutrons while keeping protons constant (D)</p> Signup and view all the answers

What charge do neutrons carry in an atomic nucleus?

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

What remains constant among all nuclides of a specific element?

<p>Atomic number (C)</p> Signup and view all the answers

Which of the following statements about protons is accurate?

<p>They carry a positive charge. (C)</p> Signup and view all the answers

What does a higher atomic mass number indicate about an element?

<p>It contains more particles in the nucleus. (D)</p> Signup and view all the answers

What is the maximum number of electrons that can occupy the second shell (n=2)?

<p>8 (A)</p> Signup and view all the answers

Which statement best describes electron binding energy?

<p>It is the energy required to remove an electron from an atom. (B)</p> Signup and view all the answers

According to the Pauli’s exclusion principle, what restriction is placed on electrons in an atom?

<p>No two electrons can occupy the same quantum state simultaneously. (A)</p> Signup and view all the answers

Which of the following correctly explains a factor affecting electron binding energy?

<p>Greater distance from the nucleus decreases binding energy. (A)</p> Signup and view all the answers

If n=3, what is the maximum number of electrons that can occupy this shell?

<p>18 (D)</p> Signup and view all the answers

What is the relationship between atomic number and electron binding energy?

<p>Increased atomic number increases binding energy. (D)</p> Signup and view all the answers

What is the unit used to express binding energy of electrons?

<p>Electron volts (D)</p> Signup and view all the answers

Which shell can have a maximum of 32 electrons?

<p>Fourth shell (C)</p> Signup and view all the answers

What is the primary feature of the atom according to Rutherford's conclusions?

<p>It has a central positively charged nucleus. (A)</p> Signup and view all the answers

Which statement describes the main aspect of the Bohr model?

<p>Electrons orbit the nucleus at discrete energy levels. (C)</p> Signup and view all the answers

What was James Chadwick's significant discovery in 1932?

<p>The neutron. (C)</p> Signup and view all the answers

What distinguishes the planetary model from the quantum model?

<p>The planetary model describes electrons as orbiting like planets. (C)</p> Signup and view all the answers

How does the mass and charge of the atomic nucleus relate to its subatomic particles?

<p>Both protons and neutrons determine the mass and charge. (D)</p> Signup and view all the answers

What is the approximate diameter of the outermost shell of atoms?

<p>$1 imes 10^{-10}$ to $3 imes 10^{-10}$ metres. (B)</p> Signup and view all the answers

Which particle in the atomic structure has a rest mass of approximately $1.675 imes 10^{-27}$ kg?

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

What is characteristic of the atomic nucleus regarding its structure?

<p>It is a dense structure containing protons and neutrons. (C)</p> Signup and view all the answers

What type of bond is formed when sodium donates an electron to chlorine?

<p>Ionic bond (D)</p> Signup and view all the answers

Which of the following statements is true regarding covalent bonding?

<p>It occurs when atoms share electrons. (A)</p> Signup and view all the answers

What characteristic is NOT associated with noble gases?

<p>High reactivity (D)</p> Signup and view all the answers

Which of the following is an example of a crystalline compound?

<p>Caesium iodide (CsI) (A)</p> Signup and view all the answers

What is one of the properties of metals?

<p>They are lustrous and malleable. (D)</p> Signup and view all the answers

Which molecule is a diatomic element?

<p>Oxygen (O2) (C)</p> Signup and view all the answers

Which of the following statements correctly describes the structure of carbon?

<p>Carbon can form extensive covalently bound structures. (B)</p> Signup and view all the answers

What happens during the formation of positive and negative ions?

<p>Atoms either donate or accept electrons. (A)</p> Signup and view all the answers

Flashcards

Atom

The basic unit of matter, considered the smallest unit that can exist independently and still retain the chemical properties of that element.

Dalton's Atomic Theory

A theory that proposes that all matter is composed of tiny indivisible particles called atoms. This was the first significant step in understanding the structure of matter.

Electron

A subatomic particle with a negative charge, discovered by J.J. Thomson through experiments with cathode rays.

Proton

A subatomic particle with a positive charge, discovered by Eugen Goldstein through experiments with canal rays (positively charged particles traveling opposite to cathode rays).

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Planetary Model of the Atom

A model of the atom where negatively charged electrons orbit a positively charged nucleus, analogous to planets orbiting the sun.

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What is matter made of?

A fundamental question in science about the nature of matter. It prompts an investigation into the building blocks of everything around us.

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Atom

The smallest unit of an element that can exist independently and still retain the chemical properties of that element.

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Why focus on Atoms?

To understand the universe, one needs to understand its basic building block, the atom. This fundamental understanding paves the way for understanding more complex concepts.

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What is the Rutherford model of the atom?

Rutherford's model suggests that an atom has a small, dense, positively charged nucleus at its center, with negatively charged electrons orbiting the nucleus at a distance.

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What is the Bohr model of the atom?

Bohr's model proposes that electrons can only occupy specific energy levels around the nucleus, which are often called shells or orbits.

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What is a neutron?

A neutron is a subatomic particle located in the atom's nucleus that has no electric charge.

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What is the atomic nucleus?

The atomic nucleus is the core of the atom, composed of protons and neutrons. It's extremely small but contains almost all the atom's mass.

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What are the three main subatomic particles and their charges?

Protons carry a positive charge; neutrons carry no charge; electrons carry a negative charge.

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What determines an element's identity?

The number of protons in an atom's nucleus determines its atomic number and its chemical identity.

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What determines the mass of an atom?

The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus.

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What are the main differences between the planetary model and the quantum model of the atom?

The planetary model describes the atom as a central nucleus with electrons orbiting around it like planets in a solar system. The quantum model describes electrons as both particles and waves, occupying regions of space around the nucleus instead of specific orbits.

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What is Atomic Mass Number?

Atomic mass number is the total count of protons and neutrons within the atom's nucleus.

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What is Atomic Number?

Atomic Number represents the number of protons found within the atom's nucleus. It defines the element.

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What are Nuclides?

Nuclides are atoms of the same element but with different numbers of neutrons, leading to variations in their atomic mass.

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What are Isotopes?

Isotopes are specific examples of nuclides, meaning they're atoms of the same element but with differing numbers of neutrons.

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How do Atomic Number and Atomic Mass Number Differ?

Unlike the atomic number, which is always constant for a given element, the atomic mass number can vary due to differences in the number of neutrons.

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What determines the stability of the nucleus?

The stability of an atomic nucleus depends on the balance between the number of protons and neutrons. Too many or too few neutrons can make the nucleus unstable.

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How do you know the number of electrons in an atom?

Since electrons carry a negative charge, and the atom itself is neutral, the number of electrons equals the number of protons within the nucleus.

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Where do electrons reside?

Electrons can exist in different energy levels around the nucleus, and these levels are quantized, meaning they can only take specific values.

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Periodic Table

The arrangement of elements in order of increasing atomic number, revealing recurring patterns in their chemical properties and electronic configurations.

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Electron Excitation

When an electron absorbs energy and moves to a higher energy level. Excited atoms are unstable and release energy as electromagnetic radiation.

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Ionization

When an electron absorbs enough energy to escape the atom, leaving behind a positively charged ion. This process creates ions with a net positive charge.

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Ionic Bonding

A chemical bond formed by the electrostatic attraction between oppositely charged ions, usually formed when one atom donates an electron to another.

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Inert Atoms

Atoms with a full outer electron shell are chemically unreactive or inert.

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Maximum Electron Capacity

The maximum number of electrons that can reside in a specific energy level is determined by the formula 2n² where 'n' represents the energy level number.

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Outermost Shell Limit

The outermost electron energy level of an atom cannot contain more than eight electrons.

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Electron Binding Energy

The energy required to remove an electron from its shell and liberate it from the atom.

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Closer to the Nucleus = Stronger Binding

Electrons closer to the nucleus have a stronger attraction to it, resulting in a higher binding energy.

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Atomic Number and Binding Energy

As the atomic number increases, the binding energy of electrons within an atom also increases because the positive charge of the nucleus becomes stronger, requiring more energy to detach the electrons.

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Distance and Binding Energy

Electrons located further from the nucleus have a weaker attraction due to the increased distance, resulting in a lower binding energy.

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Pauli Exclusion Principle

No two electrons within an atom can occupy the same quantum state simultaneously.

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Units of Binding Energy

The electron binding energy is measured in electron volts (eV) or kiloelectron volts (keV) which is equal to 1000 eV. 1 electron volt is equal to 1.6022 x 10-19 joules.

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Electron Acceptors

Atoms with an almost full outer electron level readily attract electrons, becoming negatively charged ions.

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Electron Donors

Atoms with an almost empty outer electron level easily donate electrons, becoming positively charged ions.

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Molecular Compounds

A molecule is formed when two or more atoms of different elements bond together in a specific ratio.

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Covalent Bonding

Atoms with half-filled outer electron levels share electrons to achieve a full outer shell, forming a strong bond between them.

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Crystalline Compounds

A type of molecular compound with a regular, repeating arrangement of atoms, often with strong bonds between them.

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Covalently Bound Structures

Elements like Carbon and Silicon can form extensive networks of covalently bonded atoms, resulting in diverse materials with varying properties.

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Inert Gases (Noble Gases)

These gases have a full outer electron shell, making them chemically stable and unreactive. Their inertness makes them useful in specific applications.

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Study Notes

Fundamentals of Radiation & Radiation Safety Lecture D

  • Subject: Atomic Physics
  • Lecturer: Ciara Mc Nally
  • Topic: Fundamentals of Radiation

Atoms and Matter

  • The lecture begins with a fundamental question: What is matter made of?
  • The atom is the fundamental building block of matter, but modern atomic and subatomic theories are complex.
  • Radiography phenomena are often explained using a simplified planetary model of the atom.

Atomic Theory

  • 400 BC – Concept of Particles: The idea that everything is made of tiny particles originated.
  • John Dalton (1766-1844): Dalton developed the first atomic theory of matter, proposing that elements are composed of tiny indestructible particles, atoms. Each element's atoms are identical and have the same atomic weight.
  • John Joseph Thomson (1856-1940): Discovered the electron in 1897, following research on cathode rays.
  • Eugen Goldstein (1850-1930): Experimented with cathode ray tubes. Discovered canal rays, which have the opposite charge of cathode rays.
  • Ernest Rutherford (1871-1937): Proposed that the atom is mostly empty space with a tiny, positively charged nucleus. Negatively charged electrons orbit at a distance from the nucleus.
  • Niels Bohr (1884-1962): Collaborated with Rutherford. Developed a model showing electrons orbiting the nucleus at specific energy levels, called shells or orbits.
  • James Chadwick (1932): Discovered the neutron, a neutral subatomic particle that helps reduce proton repulsion within the nucleus.

Subatomic Particle Properties

  • The atomic nucleus is small and dense, containing protons and neutrons.
    • Nuclear sizes vary between 10-15 and 10-14 meters.
    • Outermost electron shell diameters vary between 1 x 10-10 and 3 x 10-10 meters
  • Proton properties:
    • Rest mass: 1.672 x 10-27 kg, 1.007 amu
    • Rest mass energy: 938 MeV
    • Electric charge: +1
  • Neutron properties:
    • Rest mass: 1.675 x 10-27 kg, 1.009 amu
    • Rest mass energy: 939 MeV
    • Electric charge: 0
  • Electron properties:
    • Rest mass: 9.109 x 10-31 kg, 0.00055 amu
    • Rest mass energy: 0.511 MeV
    • Electric charge: -1

The Atomic Nucleus

  • The number of protons and neutrons in the nucleus determines the atom's mass and charge, and electron orbital configuration of an element.
  • Atomic mass number (A): The total number of protons and neutrons in the nucleus.
  • Atomic number (Z): The number of protons in the nucleus.

Nuclides/Isotopes

  • A nuclide is an atom characterized by a specific number of neutrons in the nucleus.
  • Isotopes of an element share the same atomic number (number of protons) but differ in the number of neutrons.
  • Examples of carbon isotopes: 12C, 13C, 14C

The Stability of the Nucleus

  • The nucleus contains positively charged protons and neutral neutrons.
  • Electrostatic repulsion between protons is countered by the strong nuclear force, which acts over a short range.
  • The energy needed to keep the nucleus intact is called the nuclear binding energy.

Electron Orbitals

  • Electrons are found in specific orbitals or shells around the nucleus.
  • The number of electrons in a stable atom equals the number of protons. Atoms are neutral electrically.
  • Electrons fill inner shells first, these are at lower energy levels.
  • The quantum mechanical model describes electron behaviour as particles and waves and the probability of locating an electron in space.
  • Cannot predict precise spatial location of an electron

Electronic Energy Levels, Electron Binding Energy and Electron Configuration

  • The further away from the nucleus, the smaller the binding energy.
  • An electron's energy levels are discrete.
  • The number of electrons each shell can hold is given by the formula: 2n2 , where n is the shell number.
    • Shell 1 (K): 2 electrons, Shell 2 (L): 8 electrons, Shell 3 (M): 18 electrons, Shell 4 (N): 32 electrons
  • Increase in atomic number = increased electron binding energy
  • Increase in distance between nucleus and electron = decreased electron binding energy.

The Periodic Table and Electron Excitation / Ionisation

  • The periodic table organizes elements based on atomic number and recurring properties. The periodic table organizes elements by valency and physical properties, determined by electronic configuration.
  • Electron excitation: An electron can gain sufficient energy to move to a higher energy level (shell).
  • Ionisation: An electron can gain sufficient energy to escape from the atom completely. This leaves a net positive charge.

Chemical Bonding

  • Ionic bonding: Atoms with nearly full or empty outer electron shells tend to transfer electrons to become ions (positive or negative). The oppositely charged ions attract, forming an ionic bond.
  • Covalent bonding: Atoms with half-full outer shells rather share electrons (covalently) to achieve a full outer shell
  • Molecular compounds: Atoms from different elements bond in fixed ratios to create a compound.
  • Other matter types: Crystalline compounds (e.g., Caesium Iodide (CsI)) and single-element materials (e.g., carbon, silicon). The arrangement of atoms affects the material's properties. Noble gases have filled outer shells resulting in inert (non-reactive) behaviour. Metals have delocalized electrons and form metallic bonds. The state of matter depends on the strength of intermolecular forces (gasses, liquids, solids).

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