HS1934 Atomic Structure and Periodic Table PDF

Atomic structure and Periodic Table Introduction to Atomic Concepts and Preparation for X-ray Production Cletus Amedu September 2024  Learning Objectives During the session, you will:  Understand the basic structure of the atom: protons, neutrons, and electrons.  Learn the con...

Atomic structure and Periodic Table Introduction to Atomic Concepts and Preparation for X-ray Production Cletus Amedu September 2024  Learning Objectives During the session, you will:  Understand the basic structure of the atom: protons, neutrons, and electrons.  Learn the concepts of atomic number, mass number, and isotopes.  Explore electron configurations and energy levels.  Review the periodic table for key concepts related to X-ray production.  The Atom  All things are composed of Matter  All matter has 3 states  Solid, liquid or gas.  All matter may be divided into elements and compounds.  Atoms are the fundamental unit of all elements and compounds.  An atom is the fundamental building block of matter, and it is the smallest unit of an element that retains the chemical properties of that element.  Overview of Atomic Structure  Atom Composition:  Atoms are composed of even smaller particles, primarily three subatomic particles: protons (+), neutrons (neutral), and electrons (-).  Protons:  Positively charged subatomic particles found in the nucleus of an atom.  Each element is defined by the number of protons in its nucleus, known as the atomic number.  For example, all carbon atoms have six protons, and this is what makes them carbon atoms.  Overview of Atomic Structure  Neutrons:  Electrically neutral (no charge) subatomic particles also found in the nucleus of an atom.  They contribute to the mass of the atom and help stabilize the nucleus by balancing the repulsive forces between positively charged protons.  Electrons: Electrons are negatively charged subatomic particles that orbit the nucleus in specific energy levels or electron shells.  Electrons are much lighter than protons and neutrons but play a crucial role in determining the chemical behaviour of an atom.  The number of electrons in an atom is typically equal to the number of protons, making the atom electrically neutral. Overview of Atomic Structure In structure all atoms have Bohr Diagram similar characteristics.  Protons: positive  Neutrons: no charge  Electrons: negative. Atoms differ in the number of these that are present. Overview of Atomic Structure  The nucleus of an atom contains protons and neutrons, tightly bound Protons together by the strong Neutrons nuclear force.  The electrons are arranged Electrons in various electron shells or energy levels surrounding the nucleus.  These energy levels can hold different numbers of electrons, with the innermost shell holding a maximum of 2 electrons and subsequent shells accommodating more. Atomic Number and Mass Number  Atomic Number (Z): Number of protons in the nucleus  Mass Number (A): Total number of protons and neutrons  Example 1: Helium (He):  Atomic Number: 2  Mass Number: 4 (2 protons + 2 neutrons) Nuclear symbols  Atomic number = no. protons in the nucleus.  Atomic mass number = no. protons & neutrons in the nucleus.  Isotopes  Definition: Atoms of the same element with different numbers of neutrons.  While all atoms of a given element have the same number of protons (which defines the element), the number of neutrons can vary.  This variation arises due to the balance between nuclear forces and electrostatic repulsion in the atomic nucleus.  Example:  Carbon-12 (6 protons, 6 neutrons)  Carbon-14 (6 protons, 8 neutrons)  Isotopes and Stability: Some isotopes are radioactive. Electrons and Energy Levels  Electron Configuration: Distribution of electrons in atomic orbitals  Energy Levels (Shells): Electrons occupy specific energy levels (n=1, n=2, etc.); they are arranged in orbital shells also called k, L, M, N…,  Maximum Capacity: 2n² electrons in each shell.  k (2) then L (8), M (18), N(32), O, P and Q.  energy level of an electron is proportional to its distance from the nucleus.  Example: Hydrogen (1 electron), Carbon (6 electrons) Electrons and Energy Levels  Atomic Structure: https://www.teachoo.com/12783/3451/Distribution-of-Electrons-in-Different-Orbits/category/Concepts/ Maximum number of electrons per shell is calculated from 2𝑛 https://www.nagwa.com/en/explainers/634167178027/  The Periodic Table of Elements  A tabular arrangement of chemical elements, organised based on their atomic number, electron configuration, and chemical properties.  Provides a concise and systematic way to understand the relationships between various elements  Key features and information about the periodic table:  Element Information: Each element is represented by a chemical symbol, which is usually one or two letters. For example, "H" represents hydrogen, "He" represents helium, and "O" represents oxygen.  Atomic Number (Z): Elements are arranged in order of increasing atomic number (the number of protons in the nucleus). The atomic number is a fundamental property of an element and is used to define its identity.  Periods: The periodic table is divided into rows called "periods." There are seven periods in total and elements within the same period have the same number of electron shells.  The Periodic Table of Elements  Groups/Families: Elements are organised into columns known as "groups" or "families." There are 18 groups, and elements in the same group share similar chemical properties due to their similar electron configurations.  Block Classification: Elements are categorised into different blocks based on the subshell that contains the last electron added. The blocks include s- block, p-block, d-block, and f-block.  Metals, Nonmetals, and Metalloids: Elements are classified as metals, nonmetals, or metalloids based on their physical and chemical properties. Metals are typically found on the left side of the periodic table, nonmetals on the right, and metalloids in between.  Transition Metals: The d-block elements in the middle of the periodic table are referred to as transition metals. They often exhibit multiple oxidation states and are known for their varied chemical properties.  Periodic Table and Atomic Properties  Inner Transition Metals: The f-block elements, also known as the lanthanides and actinides, are placed at the bottom of the periodic table. They are often separated from the main body of the table for the sake of space.  Chemical Properties: The periodic table allows scientists to predict the chemical behaviour of elements. Elements in the same group tend to have similar chemical properties due to their shared electron configurations.  Periodic Trends: The table various periodic trends, such as atomic size reveals (atomic radius), electronegativity, ionization energy, and electron affinity. These trends help in understanding how properties change across periods and groups.  Trends also prepare us for understanding elements’ behaviour in X-ray production Periodic Table and Atomic Properties  Valence Electrons: Electrons in the outermost shell.  Ionisation Energy: Energy required to remove an electron.  Reactivity: Determined by the number of valence electrons. https://iconscout.com/lottie- animations/valence-electrons X-ray Production - Relevance of Atomic Structure  X-ray Production: Involves interaction between high-energy electrons and atoms.  Electron Configurations: Important in understanding how atoms emit and absorb X-rays.  Core Concepts: Ionisation, Excitation https://iconscout.com/lottie- animations/valence-electrons  Dual Name of Elements on the PT  Some elements on the periodic table have symbols derived from their Latin or older names, leading to symbols that do not match the element's modern English name.  Examples:  Sodium (Na): The symbol "Na" comes from the Latin word "natrium."  Potassium (K): The symbol "K" is derived from the Latin word "kalium."  Lead (Pb): The symbol "Pb" is based on the Latin word "plumbum."  Iron (Fe): The symbol "Fe" is derived from the Latin word "ferrum."  Tungsten (W): The symbol "W" comes from the element's older name, "wolfram."  Gold (Au): The symbol "Au" is based on the Latin word "aurum."  Dual Name of Elements on the PT  Examples contd:  Silver (Ag): The symbol "Ag" is derived from the Latin word "argentum."  Copper (Cu): The symbol "Cu" comes from the Latin word "cuprum."  Mercury (Hg): The symbol "Hg" is based on the Latin word "hydrargyrum."  Antimony (Sb): The symbol "Sb" is derived from the element's ancient name, "stibium."  Tin (Sn): The symbol "Sn" is based on the Latin word "stannum." Review Questions  What is the atomic number and why is it important?  Explain the difference between mass number and atomic number.  What are isotopes? Provide an example.  How are electron configurations determined?  How do valence electrons affect an element's chemical behaviour? Summary  Basic atomic structure: protons, neutrons, and electrons.  Atomic number, mass number, and isotopes as key concepts.  Importance of electron configurations and energy levels.  Understanding the periodic table is crucial for studying X-ray interactions.  Punctuality – please arrive at least 5 mins before A few house each session – don’t be late – don’t disrupt the class rules We monitor attendance – if it falls below 80% (average) you will be required to attend a performance viva No eating during class Mobile phones off/silent / laptop notifications silenced Talking during lectures disrupts the speakers as well as your fellow colleagues Coats and bags off your desk Participate in discussions, ask questions – it aids your learning Respect each other Absence Notification Form If you know you are going to be absent, please let us know using the online form: https://cityunilondon.eu.qualtrics.com/jfe/form/SV_06tc0ps0t0q37Dg Additional support CUL library mechanisms Academic support team for your https://studenthub.city.ac.uk/help-and- learning support/improve-your-study-skills Discussion forum on HS1934 moodle page – useful for peer learning Academics – please get in touch if you need help, we are happy to help