topic 1- part A- Atomc and it is structure AY 2024-2025.pdf

General and Organic Chemistry DP 110 Topic 1: Atom and its structure, Electronic configuration and quantum numbers By: Dr. Eman El-labad , B.Pharm, MSc, PhD, MHPE...

General and Organic Chemistry DP 110 Topic 1: Atom and its structure, Electronic configuration and quantum numbers By: Dr. Eman El-labad , B.Pharm, MSc, PhD, MHPE 1  Chemistry is ……………. ? Chemistry The study of the nature, properties, and transformations of matter. What is matter ? Is matter infinitely divisible into ever smaller and smaller pieces? Or there is a limit ? 2 Part A: Atom and its structure, 3 Learning objective Define the concept of an atom. Describe the atomic structure, including the arrangement of subatomic particles. Identify the atomic number of an element and explain its significance. Determine the mass number of an atom and explain how it is calculated. Explain the concept of isotopes and how they differ from one another. Describe what atomic weight is and how it is determined. 4  What is Atom? What is the atomic structure ? Atom The smallest and simplest particle of an element. Atoms are composed of 3 fundamental subatomic particles called: protons (+), neutrons , and electrons (-). Protons and neutrons are packed together in the nucleus, whereas electrons move about in the large surrounding volume. The mass of an atom is concentrated in the nucleus. Electrons Negative charge Nucleus 5 What is Atom? What is the atomic structure ? The structure of the atom is determined by an interplay of different attractive and repulsive forces. Because unlike charges attract one another, the negatively charged electrons are held near the positively charged nucleus. But because like charges repel one another, the negatively charged electrons try to get as far away from one another as possible, accounting for the relatively large volume they occupy. 6  Atoms of different elements differ from one another according to ……… ? Number of Protons-----→ Atomic number The number of protons in atoms of a given element= the number of electrons in atoms of a given element called “ Atomic number” Z The sum (+) of the protons and neutrons in an atom is called the Atom is Mass number (A) Mass Number Element symbol Atomic number 7 Elements and Periodic Table (Topic 2) There are 118 elements discovered up to date (2023). Each element has specific atomic number The symbols of the known elements are normally presented in a tabular format called the periodic table. The elements can be roughly divided into three groups: metals, nonmetals, and metalloids. 8 90 7 17 Atomic number & mass number Examples: Carbon atoms with 6 protons and 6 neutrons have mass number=………………? Hydrogen atoms with 1 proton and no neutrons; have mass number= … … ? Sodium atoms with 11 protons and 12 neutrons have mass number =…………..? Atomic number = ………………….. ? 9 Worked example: Phosphorus has atomic number Z= 15 How many protons, electrons, and neutrons are there in phosphorus atoms, which have mass number A= 31 10  Isotopes & Atomic Weight All atoms of a given element have the same number of protons the atomic number Z characteristic of that element, but different atoms of an element can have different numbers of neutrons and therefore different mass numbers. Isotopes definition.: They are different atoms of same element having different numbers of neutrons and therefore different mass numbers Isotopes have same chemical behavior since they have same number of electrons. Some isotopes have radioactive properties 13 6C 12 6C Isotopes of Carbon 11  Isotopes & Atomic Weight Most naturally occurring elements are mixtures of isotopes. In a large sample of naturally occurring hydrogen atoms, for example, 99.985% have mass number A=1 (protium) and 0.015% have mass number A=2 (deuterium). It is therefore useful to know the average mass of the atoms in a large sample; a value called the element is atomic weight. For hydrogen, the atomic weight is 1.008 amu. Isotopes of Hydrogen (H) 3 1 2 1H 1H 1H 12 How atomic weight can be calculated ? https://chem.libretexts.org/Bookshelves/General_Chemistry/ChemPRIME_(Moore_et_al.)/04%3A_The_Structure_of_ 13 Atoms/4.14%3A_Average_Atomic_Weights  http://www.rsc.org/periodic-table Visit the following website interactive periodic table from Royal Society of review the different isotopes and atomic mass of the elements Let us explore these elements 14 Self Learning Atomic theory 15  Atomic Theory What is the Atomic theory ? Observation Experimental Conclusion or question Hypothesis testing / theory 1: The Question: The question …… What is matter ? Is matter infinitely divisible into ever smaller and smaller pieces? Or there is a limit ? 16  Atomic Theory What is the Atomic theory ? Observation Experimental Conclusion or question Hypothesis testing / theory 2: Hypothesis: Starts 400 BC, Democritus, “ Atomos” definition Atomos is The smallest and simplest form of matter can be divided into and still be identifiable. “atomos” in Greek meaning indivisible. Please see the links at end of lectures 17 What is the modern Atom Theory? 1-Solid sphere model, (John Dalton) Dalton drew upon the ancient Greek idea of atoms (the word atom comes from Greek “Atomos” means indivisible, His theory stated that atoms are indivisible, those of a given element are identical and compounds are combination of different types of atoms. (+): recommending atoms of particular elements differ from other elements (-): atoms are indivisible- They are composed from subatomic particles 18  Atomic Theory Conclusion What is the modern Atom Theory? Postulations of Dalton’s atomic theory All matter is composed of atoms. The atoms of a given element differ from the atoms of all other elements. Chemical compounds consist of atoms combined in specific ratios. That is, only whole atoms can combine. one A atom with one B atom, or one A atom with two B atoms, and so on. The enormous diversity in the substances we see around us is based on the vast number of ways that atoms can combine with one another. Chemical reactions change only the way that atoms are combined in compounds. The atoms themselves are unchanged. 19 Group discussion & Activity using simple models Using the given model, Let us demonstrate: 1) your understanding to the 4 postulations of Dalton’s atomic theory Hint: One cube represent an atoms Different colors represent different elements 20 Group discussion & Activity using simple models Using the given model, Let us demonstrate: 2) Demonstrate the following compound/ Chemical reactions: CH4 HCl NaOH NH3 H2O NaOH + HCl → NaCl + H2O White cube = H atom red cube= O atom Blue cube= N atom yellow cube= Na green cube= Chlorine Cl 21 Black cube= Carbon atom  Atomic Theory What is Atom? History of atomic theory Nobel prize 22 2-Plum pudding model (J.J. Thomson), noble prize: Thomson discovered electrons (which he called corpuscles) in atoms in 1897, for which he won noble prize. He subsequently proposed “ the plum pudding model of atom”. It shows the atom as composed of electrons scattered throughout a spherical cloud of positive charge. (+): recorded the electrons as components of atoms. (-): No nucleus, Did not explain later the experimental observations 3-Nuclear model (Ernest Rutherford) Rutherford fired positive charged alpha particles at a thin sheet of gold foil. Most passed through with little deflections at large angles. This was only possible if the atoms was mostly empty space, with the positive charge concentrated in the center “ nucleus” (+) released positive charge was localized in the nucleus of an atom (-)He did not expect why electrons remains in orbitals around the nucleus 23 4-Planetary model, (Niels Bohr) Electrons moved around the nucleus in orbital of fixed sizes and energies. Electron energy in this model was quantized, electrons could not occupy values of energy between the fixed energy levels (+): proposed stable electron orbitals (-): unsuccessful with heavy atoms 1st shell: n 1, 2 electron nucleus 2nd shell: n 2, 8 electron 3rd shell: n 3, 18 electron 4rd shell: n 4, 32 electron 24  Atomic Theory What is Atom? 5-Quantum model: Schrodinger stated that electrons do not move in set path around the nucleus but in waves. It is impossible to know the exact location of the electrons instead we have “ cloud of probability” called orbitals, in which we are more likely to find an electron. (+)showed electrons do not move around the nucleus in orbits but in clouds where their position is unclear (+) still widely accepted as the most accurate model of atoms Quantum number and electronic configuration –next lecture 25  Further recommended Online resources What is atom ? https://www.youtube.com/watch?v=LhveTGblGHY Dalton atomic theory https://www.youtube.com/watch?v=syi3pXJNe58 History of periodic table https://www.youtube.com/watch?v=I5H1SeepnaU 26  Learning outcome check list What is an Atom ? The smallest and simplest particle of an element. What is the atomic structure ? 12 13 6C 6C What is the atomic number of an element ? What is mass number of an atom? What is an isotope ? What is the atomic weight ? 27  Let us practice Dr.eman.m@ gmu.ac.ae 28