General Chemistry for Applied Health Students Chapter Two Lecture Notes PDF

eneral Chemistry for Applied Health studen Chapter Two Matter Prof. Dr. Yasser Mostafa Abdallah Fall 2024  ❖ MATTER  Matter is anything which occupies space (have volume) and possesses rest mass.  Matter is classified and described in tw...

eneral Chemistry for Applied Health studen Chapter Two Matter Prof. Dr. Yasser Mostafa Abdallah Fall 2024  ❖ MATTER  Matter is anything which occupies space (have volume) and possesses rest mass.  Matter is classified and described in two classes according to its physical state (as a gas, liquid and solid) and according its composition (chemical state) (as an element, compound and mixture). An element: consists of only one kind of atom. have the same physical and chemical properties. (e.g., Si, Cu).  it cannot be broken down into a simpler type of matter by any physical or chemical methods.  A compound: is a type of matter composed of two or more different elements that are chemically bound together. (e.g., H₂O, NH3, CO₂)  A mixture: is a group of two or more substances (elements and/or compounds).  Atomic structure Atom Electrons Neutrons Tiny and very light Large and heavy Particles Have no electrical Have (-) charge Protons charge Much larger than e- Have (+) Charge  The atom above, consists of one proton and one electron, is called hydrogen atom. Helium is larger than hydrogen. Helium atom ❖ The atomic number (Z) :of an element equals the number of protons in the nucleus or electrons in energy shells. ❖ mass number (A) : is the total number of protons and neutrons in the nucleus of an atom. A Every element has a symbol , so element (X) would be X Z Where X is the element (atomic symbol) 0 A is the mass number ( P+ + n ) Z is atomic number P+ Number of neutrons = mass number - atomic number, or N = A – Z 35 Thus, a chlorine atom, which is symbolized as Cl has A = 35, Z = 17, and , N = 35-17 = 18 17  Electronic configuration Schrodinger equation set of numbers called quantum numbers. Four such numbers are given the symbols n, l, ml, and ms First Quantum Number, n; Principal Energy Levels The first quantum number, given the symbol n, is of primary importance in determining the energy of an electron. n= 1, 2, 3, 4… An electron for which n = 1 is said to be in the first principal level. If n = 2, we are dealing with the second principal level, and so on.  Second Quantum Number, l; Sublevels (s, p, d, f) Each principal energy level includes one or more sublevels. quantum numbers n and l are related; l can take on any integral value starting with 0 and going up to a maximum of (n - 1). That is, l = 0, 1, 2… (n-1) If n = 1, there is only one possible value of l namely 0. This means that, in the first principal level, there is only one sublevel, for which, l =0. If n = 2, two values of l, are possible, 0 and 1. If n = 3: l = 0, 1, or 2 (three sublevels) If n = 4: l = 0, 1, 2, or 3 (four sublevels) n 1 2 3 4 l 0 0 1 0 1 2 0 1 2 3 sublevel 1S 2S 2P 3S 3P 3d 4S 4P 4d 4f  Quantum number l 0 1 2 3 Type of sublevel s p d f ns < np < nd < nf Third Quantum Number, ml; Orbitals Each sublevel contains one or more orbitals ,the third quantum number, ml. The value of ml is related to that of l. For a given value of l, ml can have any integral value, including 0, between l and –l , that is: ml = l… +1, 0, -1…, -l consider an (s) sublevel (l = 0). Here (ml ) can have only one value, 0. This means that an (s) sublevel contains only one orbital, referred to as an (s) orbital. For a (p) orbital (l = 1) (ml = 1, 0, or -1). Within a given (p) sublevel there are three different orbitals described by the quantum numbers (ml = 1, 0, -1). All three of these orbitals have the same energy. d sublevel: l =2 ml = 2,1,0,-1,-2 5 orbitals f sublevel: l =3 ml = 3,2,1,0,-1,-2,-3 7 orbitals  Fourth Quantum Number, ms; Electron Spin The fourth quantum number, ms, is associated with electron spin. Either of two spins is possible clockwise or counter clockwise. ms = + ½ or – ½ n l ml ms 1 0 (1s) 0 +1/2 , - 1/2 0 (2s) 0 +1/2 , - ½ 2 1(2p) -1,0 , +1 ±1/2 for each value of ml 0 (3s) 0 +1/2 , - ½ 3 1 (3p) -1, 0 , +1 ±1/2 for each value of ml 2 (3d) -2, -1 , 0 , +1, +2 ±1/2 for each value of ml 0 (4s) 0 +1/2 , - ½ 1 (4p) -1, 0 , +1 ±1/2 for each value of ml 4 2 (4d) -2 , -1 , 0 , +1, +2 ±1/2 for each value of ml 3 (4f) -3,-2,-1,0,+1,+2,+3 ±1/2 for each value of ml  State whether each of the following sets of quantum numbers is permissible for an electron in an atom. If a set is not permissible, explain why. (a) n= 1 , l = 1 , ml = 0 and ms = + ½ (b) n= 3 , l = 1 , ml = -2 and ms = - ½ (c) n = 2 , l =1 , ml = 0 and ms = + ½ (d) n = 2 , l = 0 , ml = 0 and ms = 1 Solve (a) Not permissible l must be less than n. (b) Not permissible ml = -l ………0 ………+l (c) Permissible (d) Not permissible ms value must be +1/2 or -1/2 only.  Explain why each of the following sets of quantum numbers is not permissible for an orbital:  (a) n=0 , l= 1 , ml = 0 and ms = +1/2  (b) n=2 , l = 3, ml =0 and ms = -1/2  (c) n= 3, l=2 , ml =3 and ms = +1/2  (d) n= 3 , l=2 , ml =2 and ms = 0 Solve (a) l must be less than n l = 0 …… (n-1). (b) l must be less than n l = 0 …… (n-1). (c) ml must be take the values between (+2, +1, 0, -1, -2) only. (d) ms takes values +1/2 or -1/2 only.  Atomic Orbitals; Shapes and Sizes  All s sublevels are spherical; they differ from one another only in size. electron in a 2s orbital is more likely to be found far out from the nucleus than is a 1s electron. P- orbitals. The electron density of the three p orbitals is directed along the x-, y-, or z-axis. The three p orbitals are located at 90° angles to each other.  Electron Configurations in Atoms Na11 1s² 2s² 2p⁶ 3S¹ B5 1s² 2s² 2p¹ O8 1s² 2s² 2p4 C6 1s² 2s² 2p² F9 1s² 2s² 2p⁵ N7 1s² 2s² 2p³ Ne10 1s² 2s² 2p⁶  Mg 12 1s² 2s² 2p⁶ 3s² Ar18 1s² 2s² 2p⁶ 3s² 3p⁶ After argon, an “overlap” of principal energy levels occurs. The next electron enters the lowest sublevel of the fourth principal level (4s) instead of the highest sublevel of the third principal level (3d). Ca20 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d sublevel start to fill with electrons from Sc (Z =21) to Zn ( Z= 30).