Chemistry for Engineering CHEM102 LECTURE 1_WS2024 Atoms-Ions-Molecules PDF

Chemistry for Engineering CHEM102 LECTURE 1_WS2024 Atoms-Ions- Molecules Dr. Marwa Hany 1 1 Marwa.hany@giu-  CHEM102 Course Description Name Room...

Chemistry for Engineering CHEM102 LECTURE 1_WS2024 Atoms-Ions- Molecules Dr. Marwa Hany 1 1 Marwa.hany@giu-  CHEM102 Course Description Name Room Office hrs E-mail number Lecturer Dr. Marwa Hany S-602 Sunday 3rd [email protected] Tuesday 3rd Teaching Assistants Amira Kasem [email protected] S-612 Monday 4th Tuesday 2nd Toka Abdelgaber S-612 [email protected] TBA Walaa Abdelaziz S-612 Wednesday 2nd [email protected] & 3rd Asmaa Mehrez S-611 [email protected] Monday 3rd &4th Rokia Abdelfattah S-611 Monday 2nd [email protected] 11/22/202 Dr. Marwa Saeed 2 2 4 Thursday 1st Hany_Lec1_CHEM102  CHEM102 Course Description Assessm ent: Assessment methods Weight Project 15% Punctuality & In-class Participation 5% Quizzes (Best 1 quiz out of 2) 10% Midterm exam 30% Final term exam 40% References :  S.S. Zumdahl, S.A. Zumdahl and D.J. DeCoste, Chemistry, 10th edn., Cengage Learning, ISBN 978-1-305-95740-4, 2016  R.Chang, Chemistry, 12th edn., McGraw Hill. ISBN 9781259254581, 2015 Dr. Marwa Saeed 33 Hany_Lec1_CHEM102  CHEM102 Course Description CMS link for Course Material https://cms.giu-uni.de 10/10/20 Dr.DrMarwa Marwa Saeed Saeed 44 23 Hany_Lec1_CHEM112 Hany_Lec1_CHEM102  Theoretical Course TopicsTopics 1. Atoms, molecules and ions 2. Quantum Numbers and Electronic configuration 3. Periodic trends 4. Chemical bonding concepts 5. Hybridization concepts 6. Stoichiometry and Quantitative expressions 7. Revision Week 8. Midterm Exams 9. Solutions- Interaction forces 10. Chemical Equilibria 11. Kinetics and Catalysis 12. Quantitative reactions in aqueous solutions (Redox-Precipitimetry) 13. Quantitative reactions in aqueous solutions (Acid base-buffer)-I 14. Quantitative reactions in aqueous solutions (Acid base-buffer)-II 15. Final Exams Practical Chemistry Course- Summer 2025 4 Dr. Marwa Saeed 54 Hany_Lec1_CHEM102  NO W! Dr. Marwa Saeed 6 6 Hany_Lec1_CHEM102  LECTURE 1- learning outcomes  Identify the main subatomic particles of the atom  Determine the number of protons, electrons, and neutrons of an element  Explain what isotopes are and how an isotope affect an element's atomic mass  Calculate average atomic mass and isotopic abundance  Give examples of metals, nonmetals and metalloids  Identify ions formation and determine the charge and number of electrons, protons and neutrons of an ion  Identify properties of different groups in the periodic table  Describe the development of the quantum theory Dr. Marwa Saeed 7 7 Hany_Lec1_CHEM102  Bohr’s Model of the Hydrogen atom- planetary model Bohr described the hydrogen atom in terms of: An electron moving in a circular orbit about a nucleus Niels Bohr (1885– 1962) Nobel Prize in Physics, 1922 for his theory explaining the spectrum of the hydrogen atom He postulated that the single electron in the hydrogen atom is allowed only to occupy certain paths called orbits, each has a particular energy, fixed in value, or quantized Dr. Marwa Saeed 8 8 Hany_Lec1_CHEM102  Bohr’s Model of the Hydrogen Bohr showed atom the energy of an electron (En) in a particular orbit When n = 1: This corresponds to the most stable energy state; called the ground state, which refers to the lowest energy state of a hydrogen electron When n is greater than 1: A hydrogen electron in this case is said to be in an excited state The higher the excited state, the farther away the electron is from the nucleus and the less it is tightly bound to the Dr. Marwa Saeed 9 9 Hany_Lec1_CHEM102  Bohr’s Model of the Hydrogen atom Bohr’s theory also provided a theoretical explanation of the emission spectrum of the hydrogen atom:  Bohr attributed the emission of radiation by an energized hydrogen atom to the electron dropping from a higher- energy orbit to a lower one and giving up a quantum of energy (a photon) in the form of light  The amount of energy needed to move an electron in the Bohr atom depends on the difference in energy levels between the initial and final states Dr. Marwa Saeed 1 10 Hany_Lec1_CHEM102 4  Problems with Bohr’s Model The success of Bohr’s theory was followed by a series of disappointments where: Bohr’s approach could not explain the emission spectra of atoms containing more than one electron, such as atoms of Helium and Lithium Wave nature of electrons wasn’t justified by Bohr’s model which described electrons only as particles; inconsistent with Louis De Broglie’s hypothesis of the dual nature of matter (particle and wave nature) in 1924 De Broglie’s Hypothesis: He hypothesized that an electron as a submicroscopic particle and owing to its very small mass could behave as a wave where its wave length is large enough to be experimentally observedDr. Marwa Saeed 1 11 1 Hany_Lec1_CHEM102  Quantum Mechanical Model of the Hydrogen atom 1926- Schrodinger model: Electrons do not move in fixed orbits but in clouds, It is impossible to know the exact location of electrons Quantum mechanical model of Hydrogen atom The blue area is the electron cloud Dr. Marwa Saeed 1 2 12 Hany_Lec1_CHEM102 0 8  Quantum Mechanical Model of the Hydrogen atom  In 1926, the Austrian physicist Erwin Schrödinger, using a complicated mathematical technique, formulated a complex mathematical equation ‘wave equation ()‘ that describes the behavior and energies of submicroscopic particles like electrons using the wave-particle duality of the electron  Unlike Bohr’s model; He stated that electrons do not exist in circular Erwin Schrödinger Nobel prize in orbits but in orbitals which are regions of space where electrons are physics, 1933 most likely to be found; also known as subshells each with characteristic shape, energy and spatial volume  We can’t say for sure the exact location of electrons, that is why we picture the electrons as being in a cloud around the nucleus Dr. Marwa Saeed 1 13 3 Hany_Lec1_CHEM102 Dr. Marwa Saeed 14 Hany_Lec1_CHEM102  Quantum Mechanical Model of the Hydrogen atom  The cloud is more dense when the probability to find an electron is high; the closer to the nucleus, the higher the probability to find an electron  Each of these orbitals is characterized by a series of numbers called the Four Quantum Numbers, which describe various properties of the orbital ( lecture 2) Dr. Marwa Saeed 1 15 5 Hany_Lec1_CHEM102  The Structure of the Atom- Sub- atomic particles An atom consists of a very dense central nucleus containing protons and neutrons, with electrons moving about the nucleus at a relatively large distance from it A neutral atomhas equalnumbers of protons, which are positively charged, and electrons, which are negatively charged Dr. Marwa Saeed 21 16 Hany_Lec1_CHEM102 9  The Structure of the Atom Most of the mass of an atom is in its nucleus, most of the volume of an atom is occupied by its electrons, and that is where our focus will be because it is the electrons that form chemical bonds Accordingly, Electrons mainly contribute to chemical properties of the atom Dr. Marwa Saeed 17 Hany_Lec1_CHEM102  The Structure of the Atom- Sub- atomic particles We cannot see atoms with the naked eye; we must use a special microscope called a Scanning Tunneling Microscope (STM) Notice how the atoms are connected to one another by “bridges,” which, as we will see, represent the electrons that interconnect atoms Dr. Marwa Saeed 21 18 Hany_Lec1_CHEM102 9  The Structure of the Atom The Atomic (Proton) Number of an element : - The number of protons in the nucleus of an atom - It determines the identity of an element as each element has its unique atomic number The Mass (Nucleon) Number of an element: - The sum of the number of protons and the number of neutrons in the nucleus - Element and its isotope(s) have different mass numbers Dr. Marwa Saeed 19 Hany_Lec1_CHEM102  The Structure of the Atom EXAMP LE:  Data derived from Atomic number (also called Proton number): Magnesium has 12 protons (p+), 12 electrons (e-) Number of protons = Number of electrons= 12  Data derived from Mass number : Number of Neutrons = Mass number- Atomic number = 12 neutrons Dr. Marwa Saeed 20 Hany_Lec1_CHEM102  Isotopes- when the neutrons’ numbers differ  Atoms that have the same atomic number, but different mass numbers are called isotopes  There are naturally occurring isotopes and isotopes that are artificially produced  Isotopes show almost identical chemical properties Electrons 1 1 1 EXAMPLE: Hydrogen Isotopes Protons 1 1 1 Neutrons 0 1 2 The 3 isotopes of hydrogen have different physical properties  Protium is the hydrogen’s most common isotope  It accounts for more than 99.98 percent of all universe hydrogen  Tritium is hydrogen’s radioactive isotope Dueterium H2O (heavy water) ice is Dr. Marwa Saeed denser than Protium H20 ice 21 Hany_Lec1_CHEM102 Isotopes- when the neutrons’ numbers differ Dr. Marwa Saeed 22 Hany_Lec1_CHEM102  Isotopic Abundance / Average Atomic Mass Because most elements exist as mixtures of several stable isotopes, the atomic mass of an element in the periodic table is the average of the masses of its isotopes EXAMPLE: What is the average atomic mass of carbon? STRATEGY: Naturally occurring carbon is largely a mixture of two main isotopes: % abundance of 14C 98.89% 12 C (mass = 12 amu) 1.11% 13 C (mass = 13.003355 is so low that it can amu) be ignored in this calculation So, average atomic mass = % abundance /100 x atomic mass of 1st isotope + % abundance /100 x atomic mass of 2nd isotope 0.9889 x 12 amu + 0.0111 x 13.003355 amu = 12.011 amu This makes sense where carbon is predominantly 12C, so its average atomic mass should be Dr. Marwa Saeed 23 close to 12 amu Hany_Lec1_CHEM102  Isotopes- when the neutrons’ numbers differ Now, Try it yourself ! : Identify the main subatomic particles in the following isotope of copper: 63 29 Cu? Protons : 29 Atomic number: Electrons 29 29 Mass number: : 63-29: 63 34 Neutrons: Which of the following is the expected other isotope of copper? 64 63 29 Cu 30 Cu Dr. Marwa Saeed 24 Hany_Lec1_CHEM102 The Modern Periodic Table Dr. Marwa Saeed 25 Hany_Lec1_CHEM102  The Modern Periodic Table In the periodic table: The horizontal rows are named periods and are labeled from 1 to 7 Elements are arranged in these rows by increasing atomic number (shown above the element symbol) The vertical columns are named groups and are numbered from 1 to 18 starting from the left Dr. Marwa Saeed 26 Hany_Lec1_CHEM102  The Modern Periodic Table In the periodic table: Elements in Groups 1, 2 & 13 to 18 are referred to as Main group (Representative) elements (group A elements) Elements in groups 3 to 12 are the Transition metals (group B elements) Elements of group 1 are referred to as the Alkali metals and those in group 2 are called Alkaline earth metals Elements of group 17 are the Halogens and the Noble gases constitute group 18 (inert or rare gases) Dr. Marwa Saeed 27 Hany_Lec1_CHEM102  The Modern Periodic Table In the periodic table: Elements in the same group have the same physical and chemical properties as they have the same number of valence (outer most orbital) electrons Number of valence electrons is equal to the group number Dr. Marwa Saeed 28 Hany_Lec1_CHEM102  High Reactivity of Alkali The MOST reactive metals metals followed by alkaline earth metals, never found free in nature React violently with water, form alkaline solutions of metal hydroxides and Hydrogen gas is produced2inNaa + 2 H 2 O vigorous exothermic 2NaOH + H2 reaction Dr. Marwa Saeed 29 Hany_Lec1_CHEM102  The Modern Periodic Table In the periodic table: The two rows of elements at the bottom of the body of the periodic table are a collection of transition metals called the lanthanides and actinides , also called rare earth metals or inner transition elements These elements are conventionally set apart to keep the table from being too wide Dr. Marwa Saeed 30 Hany_Lec1_CHEM102  The Modern Periodic Table From left to right across any period, the physical and chemical properties of the elements change gradually from metallic to nonmetallic Periodic table can be broken into 3 main parts Metals Metalloids Nonmet  Good conductors of  Intermediate (semiconductors) properties between those of als heat and electricity metals and nonmetals  Poor conductors of  All solids except Boron Silicon Germanium heat and (B) (As) (Si) (Ge) electricity mercury (liquid) Arsenic Polonium Antimony (Sb) Tellurium (Po) (Te) E.g. silicon: shiny, moderately conducts electricity but doesn’t conduct heat well, Dr. Marwa Saeed 31 Hany_Lec1_CHEM102 brittle  Ions- when electrons number differ  Ions are charged atoms or groups of atoms with either a negative or positive charge indicated by a superscript after the symbol  Ions form when one or more electrons are added to or removed from an atom or molecule Reca ll ! 1 electron in the outer 7 electrons in the outer shell of sodium atom ( shell of chlorine atom 11p+, 11e-) ( 17p+, 17e-) (2,8,1) (2,8,7) 8 electrons in the outer 8 electrons in the outer shell of sodium shell of chloride ion ion( 11p+, 10e-) ( 17p+, 18e-) (2,8) (2,8,8) Dr. Marwa Saeed 32 Hany_Lec1_CHEM102 Ions- when electrons number differ Dr. Marwa Saeed 33 Hany_Lec1_CHEM102  Ions- when electrons number differ  Atoms form ions to become stable after achieving a full valence shell (complete octet) and have the same number of electrons like its nearest noble gas  All these Na+, Mg2+ and Al3+ have the same number of electrons as the nearest noble gas; Neon atom (10 electrons) , hence they are called ISOELECTRONIC Dr. Marwa Saeed 34 Hany_Lec1_CHEM102  Ions- when electrons number differ Metal atoms tend to lose electrons to form positively charged ions called cations Non-metal atoms tend to gain electrons to form negatively charged ions called anions Note the Pattern: Elements in groups 1, 2, and 3 tend to form 1+, 2+, and 3+ ions, respectively (electropositive elements) Elements in groups 5, 6, and 7 tend to form 3−, 2−, and 1− ions, respectively Dr. Marwa Saeed 35 Hany_Lec1_CHEM102  Ions- when electrons number differ Now Try it yourself: Determine the numbers of protons, neutrons, and electrons in: Sulphide Barium S2 Ba2 anions - cations + STRATE  GY: In Neutral atoms: The number of protons is equal to the number of electrons  In both Ions and Neutral atoms: The atomic number always corresponds to the protons number Sulphide Barium Ba2 anions S2- cations + Ba2+ has 2 more protons than S has 2 more electrons 2- electrons ( 56 protons, 54 than ( 16 protons18 protons, electrons) electrons) Neutrons unchanged: 137- Neutrons unchanged: 56= 81 32-16= 16 Dr. Marwa Saeed 36 Hany_Lec1_CHEM102  Naming Cations & Cation name: Anions element name + ion Anion name: element root name + changing the end of the name to –ide Dr. Marwa Saeed 37 Hany_Lec1_CHEM102  Naming Binary Ionic Compounds (Type I) Binary ionic compound : An ionic compound that contains only two elements, one present as a cation and one as an anion The cation is always named first and the anion second The subscripts ( Xm) in the empirical formula can also be obtained by referring to group number then crossing charges, reduce the subscripts to their simplest ratio if needed Li N + -3 1 Mg2+ O2- Dr. Marwa Saeed 38 Hany_Lec1_CHEM102  Naming Binary Ionic Compounds Many transition (Type metals form more than II) of positive one type ion, in this case Roman numerals indicate the charge of the cation Another older system for naming these ionic compounds: The name of the ion with the higher charge ends in -ic and the one with the lower charge ends in –ous Example: Fe3+ is called the ferric ion, and Fe2+ is called the ferrous ion C B o r + -1 C 2 C a l + - A 2 O 1 l - + 2 Dr. Marwa Saeed 39 3 Hany_Lec1_CHEM102  Molecu les A molecule is an aggregate of at least two atoms in a definite arrangement held together by chemical forces (called chemical bonds) Molecules are called compounds ONLY when they are composed of two or more elements Some elements exist as “diatomic E.g Hydrogen, molecules”; Nitrogen, Oxygen, Halogens Most containmore than two atoms,called molecules “polyatomic molecules”; E.g NH3, H2O Dr. Marwa Saeed 40 Hany_Lec1_CHEM102  CHNOPS: The Six Most Abundant Elements of Life  Most biological molecules are products of covalent combinations of six important elements ( bulk elements), whose chemical symbols are CHNOPS present in relatively large amounts in living organisms along with sodium, magnesium, potassium, calcium and chlorine (macrominerals) Dr. Marwa Saeed 41 Hany_Lec1_CHEM102 Dr. Marwa Saeed 42 Hany_Lec1_CHEM102  References R.Chang, Chemistry, 12th edn., chapter 2 Zumdahl, Chemistry, 10th edn., chapter 2 Zumdahl, Chemistry, study guide, 10th edn., chapter 2 Relevant websites and internet resources Dr. Marwa Saeed 43 Hany_Lec1_CHEM102  Nice to Watch! https://www.youtube.com/watch?v=wiINTUZoAiw https://www.youtube.com/watch?v=j7JcyDBHCBc&list=PLLG7h7fPoH8Ixhq05cFNvgAt 3xIklAfJ3&index=2 https://www.youtube.com/watch?v=faB9Gb7bl9I&list=PLLG7h7fPoH8Ixhq05cFNvgAt 3xIklAfJ3&index=1 https://www.youtube.com/watch?v=ukGLH_NrFH8&t=145s https://www.youtube.com/watch?v=uc_9g5vPZ9s https://www.youtube.com/watch?v=yP8bg PA5mdU https://www.youtube.com/watch?v=YGaBiFFFw5A Dr. Marwa Saeed 44 Hany_Lec1_CHEM102