RCSI International Medical Commencement Programme Chemistry and Matter PDF

International Medical Commencement Programme M5.1.1 Introduction to Chemistry and Matter Dr. Dar r en Gr iffit h Learning outcomes M 5.1.1 Introduction to Chemistry and Matter Explain what is chemistry? Discuss why it is important to study chemistry?...

International Medical Commencement Programme M5.1.1 Introduction to Chemistry and Matter Dr. Dar r en Gr iffit h Learning outcomes M 5.1.1 Introduction to Chemistry and Matter Explain what is chemistry? Discuss why it is important to study chemistry? Define ‘matter’, ‘elements’, ‘atom’, ‘mass number’, atomic number’, ‘isotope’. Identify the number of protons, neutrons and electrons in given elements of the periodic table. Calculate relative atomic mass of given elements. M5.1.1 Introduction to Chemistry and Matter 2 What is Chemistry? Chemistry is the study of matter or materials, the changes it undergoes and the energy associated with these changes What are certain materials (solids, liquids or gases) made of? What types of changes (reactions) do these materials undergo? The materials found on earth are either mixtures or pure substances All chemicals M5.1.1 Introduction to Chemistry and Matter Useful Definitions! 3 Mixtures and Substances Mixtures can be separated into at least two pure substances Examples of mixtures? Pure substances are either compounds or elements Compounds can be broken down into the elements of which they are made Examples of compounds? M5.1.1 Introduction to Chemistry and Matter 4 Matter and Elements Matter is anything that occupies space and has mass. All matter is made up of elements. Ac Actinium Ag Silver Al Aluminum Am Americium Ar Argon As Arsenic At Astatine Elements are substances that cannot be broken down into Au Gold simpler substances by chemical means. B Boron Elements are composed of atoms. Ba Barium All atoms of an element are identical. Be Beryllium ………………. M5.1.1 Introduction to Chemistry and Matter 5 Elements and the Periodic Table A Chemists directory of elements As of September 2024 there are 118 elements. Some, like gold, silver, copper and carbon, have been known for thousands of years. Others, such as livermorium and flerovium have only recently been created by scientists. All matter is made up of these elements! http://www.iupac.org/news/news-detail/article/about-element-115-time-to-make-more-room-at-the-table.html M5.1.1 Introduction to Chemistry and Matter 6 Elements Each element has a one or two letter symbol, eg. H and Co Recall elements are substances made up of the same types of atoms 99% of the human body is constructed from only 4 elements C H N O M5.1.1 Introduction to Chemistry and Matter 7 Elements and Atoms Each element has a name and a one or two letter symbol, e.g. H, Ag and Co The symbols are abbreviations of the name, mostly the English name but not always: Silver : Argentum : Ag Iron: Ferrum : Fe The first but never the second letter of the symbols are capiltalized! M5.1.1 Introduction to Chemistry and Matter 8 Elements and Atoms Recall elements are substances made up of the same types of atoms What is an atom? An atom is a basic unit of matter. They are so small that they cannot be visualised with the most powerful of microscopes. An atom is the smallest particle of an element If there are 118 different elements there are 118 different types of atoms M5.1.1 Introduction to Chemistry and Matter 9 A Simple Model of an Atom An atom consists of a dense nucleus containing positive charged protons and uncharged neutrons. Orbiting the nucleus are negatively charged lightweight electrons Nucleus Protons Neutrons Electrons An atom is held together by forces of attraction between the electrons and the protons. M5.1.1 Introduction to Chemistry and Matter 10 Properties of Subatomic Particles Nucleus Protons Neutrons Electrons Particle Symbol Location Mass Charge Proton p+ Nucleus 1.67 x 10-27 kg (1) +1 Neutron n Nucleus 1.68 x 10-27 kg (1) 0 Electron e- Orbiting nucleus 9.1 x 10-31 kg -1 M5.1.1 Introduction to Chemistry and Matter 11 Atomic Number The atomic number (Z) of an element is the number of protons in the nucleus of an atom of that element The number of protons in the nucleus of an atom tell us what type of element the atom is, i.e. the number of 4 protons reveals the identity of the atom He Z 2 Helium Refer to your periodic table and the atomic no’s! A hydrogen atom always has 1 proton A carbon atom always has 6 protons A platinum atom always has 78 protons A uranium atom always has 92 protons M5.1.1 Introduction to Chemistry and Matter 12 Atomic Number and Electrons An atom containing an equal number of protons and electrons is electrically neutral, otherwise it has a positive or negative charge and is an ion. Therefore electrically neutral atoms have the same number of protons and electrons Refer to your periodic table and the atomic no’s! An electrically neutral hydrogen atom has 1 electron An electrically neutral carbon atom has 6 electrons An electrically neutral platinum atom has 78 electrons An electrically neutral uranium atom has 92 electrons M5.1.1 Introduction to Chemistry and Matter 13 Mass Number The total number of protons and neutrons in the nucleus of an atom is called the mass number (A) of that atom A 4 He 2 Helium Refer to your periodic table and the mass no’s! M5.1.1 Introduction to Chemistry and Matter 14 Atomic Number and Mass Number The number of neutrons in nucleus = Mass number – Atomic number, i.e. Number of neutrons = A- Z Atomic No. Mass No. Protons Neutrons Electrons 9 4 9 4 5 4 Be 4 19 9 19 9 10 9 F 9 23 Na 11 23 11 12 11 11 12 6 6 C 6 12 6 6 14 7 14 7 7 7 N 7 M5.1.1 Introduction to Chemistry and Matter 15 Isotopes Atoms of an element that have the same number of protons but different number of neutrons are called isotopes of that element, or Atoms of an element that have the same atomic number but different mass number are called isotopes of that element No neutron ! Protium Deuterium Tritium 1H 2H 3H protons 1 1 1 neutrons M5.1.1 Introduction to Chemistry and Matter 16 Isotopes C-12 (Carbon-12) and C-13 (carbon-13) are the two most abundant isotopes with the following percent natural abundances: 12C - 98.89 % 13C - 1.11 % 12 C 14 C 6 13 C 6 6 Unstable Stable isotopes are those that are not radioactive! Hydrogen aside all isotopes of an element share the same name and symbol! M5.1.1 Introduction to Chemistry and Matter 17 Isotopes Percent natural abundances, e.g. 90.48, 0.27 and 9.25 for Ne-20 (“Neon twenty”), Ne-21 and Ne-22 respectively, are based on numbers not masses. Therefore 9,048 of every 10,000 neon atoms are Ne-20! Some elements in nature exist as only one type of atom! i.e. they do not have isotopes, e.g. Al-27, (aluminium twenty seven”) M5.1.1 Introduction to Chemistry and Matter 18 Relative Atomic Mass Most elements have two or more different isotopes Therefore the mass of an element (periodic table) accounts for the natural abundance of all isotopes of that element Relative atomic masses are therefore not whole numbers The relative atomic mass of an element is the average mass of an atom of the element relative to one-twelfth the mass of an atom of carbon-12 M5.1.1 Introduction to Chemistry and Matter 19 Relative Atomic Mass The relative atomic mass is the average mass of the isotopes, taking their relative natural abundances into account Natural abundance Atomic Mass 12C 98.89% 12.00 13C 1.11% 13.0034 Mass of 100 atoms = (98.89 x 12.00) + (1.11 x 13.0034) 100 = 1201/100 atomic mass units (a.m.u.) Average mass of one atom = 12.01 a.m.u. M5.1.1 Introduction to Chemistry and Matter 20 Relative Atomic Mass Another example: Chlorine 2 isotopes: 35 Cl and 37 Cl Natural abundance Atomic Mass 35 Cl 75.77% 34.97 37 Cl 24.23% 36.97 Mass of 100 atoms = (75.77 x 34.97) + (24.23 x 36.97) 100 = 3545/100 atomic mass units (a.m.u.) Average mass of one atom = 35.45 a.m.u. M5.1.1 Introduction to Chemistry and Matter 21 Recap M 5.1.1 Introduction to Chemistry and Matter Explain what is chemistry? Discuss why it is important to study chemistry? Define ‘matter’, ‘elements’, ‘atom’, ‘mass number’, atomic number’, ‘isotope’. Identify the number of protons, neutrons and electrons in given elements of the periodic table. Calculate relative atomic mass of given elements. A visual interpretation of the periodic table of the elements http://www.rsc.org/chemsoc/visualelements/index.htm M5.1.1 Introduction to Chemistry and Matter 22 Reading List Semester I M5.1.1 Introduction to Chemistry and Matter 23 M5.1.1 Introduction to Chemistry and Matter 24 Thank you F O R M O R E I N F O R M AT I O N P L E A S E C O N TA N T Dr. Dar r en Gr iffit h EMAIL: [email protected] 25