Diagnostic Radiography: Binding Energy and Ionisation

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Questions and Answers

What is atomic mass primarily determined by?

The number of protons and electrons in an atom

The number of protons and neutrons in an atom (correct)

The number of neutrons and electrons in an atom

The arrangement of electrons around the nucleus

Which unit is commonly used to express atomic mass?

Atomic mass unit (amu) (correct)

Kilogram (kg)

Gram (g)

Milligram (mg)

What defines one atomic mass unit (amu)?

The mass of a single proton

One-twelfth the mass of a carbon-12 atom (correct)

The mass of a single neutron

One-sixteenth the mass of an oxygen-16 atom

What factor primarily affects ionisation energy?

The distance of the nucleus from the electrons Signup and view all the answers

Which statement about protons and neutrons is correct?

Neutrons and protons have nearly the same mass Signup and view all the answers

What is the approximate mass of 1 amu in kilograms?

1.66×10−27 kg Signup and view all the answers

What happens to electrons in atoms that lose them?

They become positively charged cations. Signup and view all the answers

Which of these is NOT a part of an atom’s atomic mass calculation?

Total charge of the nucleus Signup and view all the answers

Which factor has the least impact on ionization energy?

Number of neutrons. Signup and view all the answers

Which term correctly describes the smallest part of a substance that cannot be broken down chemically?

Atom Signup and view all the answers

Why does ionization energy decrease as atomic size increases?

Electrons are farther from the nucleus. Signup and view all the answers

How does higher nuclear charge generally affect ionization energy?

It increases ionization energy. Signup and view all the answers

What occurs to the successive ionization energies of an element as electrons are removed?

They increase. Signup and view all the answers

What is the significance of the electron shielding effect?

It decreases the effective nuclear charge felt by outer electrons. Signup and view all the answers

Which shell is closest to the nucleus and has the highest binding energy for electrons?

K-shell. Signup and view all the answers

Which statement about the binding energy of an electron is true?

Binding energy measures the attraction between the nucleus and the electron. Signup and view all the answers

What does a larger mass defect indicate about an atom?

It corresponds to a more tightly bound atom. Signup and view all the answers

What is the function of the binding energy in relation to atomic structure?

It determines the stability of the atomic nucleus. Signup and view all the answers

Which formula represents Einstein's mass-energy equivalence used for binding energy calculation?

E = Δmc^2 Signup and view all the answers

How does binding energy relate to the production of characteristic X-rays?

It plays a major role in the production of characteristic X-rays. Signup and view all the answers

What occurs to an atom during the ionization process?

It gains or loses electrons. Signup and view all the answers

Which of the following is true regarding the nuclear binding energy of isotopes?

It affects their stability and radioactive properties. Signup and view all the answers

What is the significance of electron binding energy within an atom?

It measures how tightly electrons are held to the nucleus. Signup and view all the answers

How do X-rays and gamma rays interact with matter?

Binding energy determines their interaction with matter. Signup and view all the answers

Study Notes

Lecture Introduction to Diagnostic and Therapeutic Radiography Students

Ensure attending the correct lecture session
Fill all seats, prioritizing those furthest from the entrance doors

Basics of Binding Energy and Ionisation of Atoms

Lecture topic: Introduction to the Diagnostic and Therapeutic Radiography Professions
Module code: HS1934
Lecturer: Dr Benard Ohene-Botwe, Senior Lecturer, Diagnostic Radiography
Contact details: [email protected], +44 (0)20 7040 4387

Objective

Defining and highlighting nuclear binding energy, ionisation and the factors affecting ionisation energy
Preparing students to understand ionisation in x-ray production and its interactions with matter

Atomic Structure

Atom: The smallest part of a substance that cannot be broken down chemically
Nucleus: Contains protons and neutrons
Orbiting electrons: Negatively charged particles orbiting the nucleus

Atomic Mass

Atomic mass (atomic weight): The mass of an atom
Calculation of atomic mass: Equal to the sum of protons and neutrons in the nucleus (mass number)
Mass of electrons are negligible compared to protons and neutrons
Unit: Atomic mass unit (amu) or Dalton (Da or u)
Conversion: 1 amu ≈ 1.66x10⁻²⁷ kg

Typical Atomic Masses (in amu)

Proton: 1.00728
Neutron: 1.00867
Electron: 0.00055
Protons and neutrons have nearly the same mass; neutrons are slightly heavier
The electron's mass is significantly smaller compared to the protons and neutrons
Watch the first few minutes of the provided video on Binding Energy

Atomic Mass Defect

Mass defect: The difference between the actual mass of an atom and the sum of the masses of its components (protons, neutrons, and electrons).
Example, Helium: The mass of a Helium atom is 4.00260 amu, but the mass of its components is 4.03298 amu; the difference is thus the mass defect.
Significance: The "missing" mass equals the binding energy holding the atom together.

Converting Mass Defect into Binding Energy

Einstein's mass-energy equivalence formula: E = Amc² (or E = Am x c²)
E: Binding energy (in joules or MeV)
Am: Mass defect (in kilograms or atomic mass units, u)
c: Speed of light (3×10⁸ m/s)

Binding Energy

Binding energy: The energy that holds the nucleus together
Higher mass defect corresponds to a more tightly bound (more stable) atom
The minimum energy needed to break atom into its components

Electron Binding Energy

Electron binding energy: The energy required to remove an electron from an atom or ion in the gaseous state
It is typically equal to or greater than the binding energy of the electron

Factors Affecting Ionisation Energy

Distance from the nucleus: Electrons closer to the nucleus are more tightly bound and require more energy to remove. Larger atoms have electrons farther from the nucleus
Higher nuclear charge: A higher number of protons in the nucleus creates a stronger positive charge attracting electrons meaning more energy is required to remove them
Number of electrons: As electrons are removed, the positive charge of the nucleus increases, attracting remaining electrons more strongly, and requiring more energy to remove subsequent electrons
Electron shielding: Inner electrons shield outer electrons from the full nuclear charge, weakening the attraction and requiring less energy to remove the outer electrons

Ionisation Process and Energy

Ionisation: The process where an atom or molecule gains or loses electrons, becoming an ion
Ionisation energy: The energy needed to remove an electron from an atom or an ion in the gaseous state
Ionisation diagram: Illustrates the energy involved, with Proton, Neutron, Electron and Atom shown

Significance of Binding Energy in Radiography

Nuclear binding energy: Key factor determining atomic stability; higher binding energies indicate greater stability. Lower binding energies correlate with increased susceptibility to radioactive decay
Isotope properties: Binding energies of isotopes affect their stability and radioactive properties
Radioisotope selection: Understanding binding energy facilitates selection of appropriate radioisotopes for nuclear medicine imaging techniques (PET and SPECT)
Electron binding energy: Plays a crucial role in characteristic X-ray production
Interaction with X and gamma rays: Binding energies determine how X-rays and gamma rays interact with matter

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Description

This quiz explores the key topics in Diagnostic and Therapeutic Radiography, focusing on nuclear binding energy, ionisation, and their implications in x-ray production. Students will be prepared to understand how these principles impact the interactions of matter with radiation. It's an essential part of the HS1934 module led by Dr. Benard Ohene-Botwe.