Chapter 2 Atom, Elements and Compounds PDF

(Pharm Chem 11) Adopted from PACOP PHARMACEUTICAL INORGANIC CHEMISTRY W/ QUALITATIVE ANALYSIS Prepared By: Criezl L. Bajado, RPh CHAPTER 2: ATOMS, ELEMENTS AND COMPOUNDS Atom, Element, Compound  Particles can be atoms, molecul...

(Pharm Chem 11) Adopted from PACOP PHARMACEUTICAL INORGANIC CHEMISTRY W/ QUALITATIVE ANALYSIS Prepared By: Criezl L. Bajado, RPh CHAPTER 2: ATOMS, ELEMENTS AND COMPOUNDS Atom, Element, Compound  Particles can be atoms, molecules or ions. Atoms are single neutral particles. Molecules are neutral particles made of two or more atoms bonded together. An ion is a positively or negatively charged particle.  The simplest structural unit of an element is an atom. All elemental molecules are made of atoms of a single element.  Molecules of compounds have atoms of two or more different elements.  Atoms Elements Molecules Compounds -The smallest -A pure -Formed when -Formed when unit of matter substance two or more two different and has three consisting of one atoms join elements join main parts type of atom and together together (protons, can be identified chemically -All compounds neutrons, and by its atomic -Can be the same are molecules, electrons) number (# of atoms but all molecules -The basic protons) -Example: are not building blocks of -All elements are Oxygen compound matter found on the Molecule, Water, -Example: Water -Smallest part of Periodic Table of Nitrogen and Carbon an element Elements and Molecule, dioxide -Example: have a chemical Carbon dioxide Oxygen, symbol Hydrogen, -Example: Nitrogen Oxygen’s atomic number is 8 Atomic Theory  Democritus Matter is made up of small indivisible particles called “atomos” John Dalton “Billiard Ball Model” (an atom is a hard indestructible sphere) Dalton's Atomic Theory: 1. Matter is made up of atoms 2. All atoms of a given element are alike 3. Atoms enter into a combustion with other atoms to form compounds but remain unchanged during ordinary chemical reactions His theory was accepted for 100 years until it was disproved by the subatomic particles J.J. Thomson “Raisin Bread Model”; discovered the electrons Eugen Goldstein First discovered the “proton” but did not name it yet Ernest Rutherford Proved the presence of proton through his “Gold Film Experiment” Coined the term “proton” “Atom is mostly an empty space” Niels Bohr Proposed the “Planetary Model” Erwin Schrödinger Proposed the “Quantum Mechanic Model” or also known as “Electron Cloud Model” According to him, electrons move in a 3D structure (orbitals) James Chadwick Discovered the “neutron” (no charge) Element  Atomic number = number of protons Mass number = (protons + neutrons) Neutron = (mass number – protons) Electron = (proton – charge)  Periodic Table of Elements organizes the chemical elements according to the number of protons that each has in its atomic nuclei elements are arranged from left to right and top to bottom in increasing atomic number in the old IUPAC, there were only 8 ( I - VIII) groupings identified separated by family as A & B UPDATED new IUPAC numbering, consist of 18 groups... no more A & B divided into sections or blocks ( s, p d, f ) representing the atoms energy sublevels being filled with its valence electrons  The purpose of the periodic table is to summarize and predict the properties of elements  Periodic Classification of Elements 1.) Classification of elements – The arranging of elements into different groups on the basis of the similarities in their properties is called classification of elements – The classification of similar elements into groups makes the study of elements easier – There are about 114 different elements known so far. Periodic Classification of Elements 2. Early attempts at classification of elements – The earliest attempt to classify elements was grouping the then known elements (about 30 elements) into two groups called metals and non- metals – The defect in this classification was that it had no place for metalloids (elements which have properties of both metals and non metals )which were discovered later  Who were the Contributors of the Periodic Table of Elements? Antoine-Laurent Lavoisier – 1789, grouped the elements as metals and nonmetals Johann Wolfgang Döbereiner – He classified the elements in groups of 3 called “triads”, based on similarities in properties and that the atomic mass of the middle member of the triad was approximately the average of the atomic masses of the lightest elements  John A. Newlands – 1863, He arranged the elements in the order of increasing atomic mass – The eight elements starting from a given one is a kind of repetition of the first, like the eight note of the octave of music and called it the “Law of Octaves” However, after calcium, every 8th element did not possess properties similar to that of the 1st  Julius Lothar Meyer – He plotted a graph showing an attempt to group elements according to atomic weight Dmitri Mendeleev – 1869, He worked out a Periodic Table of Elements that were arranged in the order of increasing atomic weights with a regular repetition (periodicity) of physical and chemical properties – Father of Periodic Table  Henry Moseley – He arranged the elements in the order of increasing atomic numbers, which relates that the properties of the elements are periodic functions of their atomic number – This is known as the Modern Periodic Law.  New Elements as of 2016 (until present) Periodic Trends  Atomic Radius – the 1/2 distance between 2 nuclei Metallic Property / Character – level of reactivity of a metal Ionization Potential – minimum amount of energy required to remove the most loosely bound electron, the valence electron Electron Affinity – the amount of energy released or spent when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion (-)  Electronegativity – is a measure of the tendency of an atom to attract a bonding pair of electrons  Electropositivity – tendency of atoms to lose electrons and form positive ion IA ALKALI METALS [H, Li, Na, K, Rb, Cs, Fr] IB COINAGE METALS [Cu, Ag, Au] IIA ALKALINE EARTH [Be, Mg, Ca, Sr, Ba, Ra] METALS IIB ZINC FAMILY OR [Zn, Cd, Hg] VOLATILE METALS IIIA BORON FAMILY OR [B, Al, Ga, In, Tl] ICOSAGENS IIIB SCANDIUM SUBGROUP [Sc, Y, Lanthanides, Actinides] IVA CARBON FAMILY OR [C, Si, Ge, Sn, Pb] CRYSTALLOGENS IVB TITANIUM SUBGROUP [Ti, Zr, Hf]  VA NITROGEN FAMILY OR [N, P, As, Sb, Bi] PNICTOGENS VB VANADIUM SUBGROUP [V, Nb, Ta] VIA CHALCOGENS OR [O, S, Se, Te, Po] OXYGEN FAMILY VIB CHROMIUM SUBGROUP [Cr, Mo, W, U] VIIA HALOGENS [F, Cl, Br, I, At] VIIB MANGANESE [Mn, Te, Re, Bh] SUBGROUP VIIIA INERT/ NOBLE/ STABLE [He, Ne, Ar, Kr, Xe, Rn] GASES VIIIB IRON TRIADS [Fe, Co, Ni] PALLADIUM TRIADS [Rh, Ru, Pd] PLATINUM TRIADS [Os, Ir, Pt] Quantum Mechanics Principles of Electron Configuration ELECTRON CONFIGURATION – the distribution of electrons of an atom or molecule in an orbitals – or the shorthand method of writing the location or where the electrons are around a nucleus – governed by these principles: Pauli's Exclusion Principle Aufbau's Principle Hund's Rule Pauli’s Exclusion Principle Aufbau’s Principle Hund’s Rule  Exceptions to Expected Electron Configurations There are some exceptions to the order of filling of orbitals. For example, the electron configurations of the transition metals chromium (Cr) and copper (Cu), are not those we would expect. Rather, Cr and Cu take on half-filled and fully- filled 3d configurations.  The electron configuration of chromium (Cr) includes a half-filled 3d subshell. Cr: 1s2 2s2 2p6 3s2 3p6 4s1 3d5 The electron configuration of copper (Cu) includes a fully-filled 3d subshell. Cu: 1s2 2s2 2p6 3s2 3p6 4s1 3d10 Figure 1.9.10 indicates which elements have a non-standard configuration. Electron Configurations of Transitional Metal Ions Transition metal elements are unique in the sense that they can have multiple oxidation states. While negative oxidation states are possible for some transition metal elements, we will focus on the positive oxidation states, which are more common.  Steps: 1. Write the electron configuration for the neutral atom and then determine the number of electrons that are lost to form the cation. 2. The electrons will be removed from the highest energy shell in the neutral configuration. This means that electrons will be removed from the 4s subshell before any electrons are removed from the 3d subshell, and similarly electrons will be removed from the 5s subshell before they are removed from the 4d subshell. 3. If the highest energy s subshell is empty, then additional electrons will be removed from the highest energy d subshell. Write an electron configuration for V4+. Solution 1. Write the configuration of the neutral atom. V: 1s2 2s2 2p6 3s2 3p6 4s2 3d3 2. Determine how many electrons were lost. V4+ was formed by the loss of four electrons. 3. Remove electrons from the highest shell, starting with the highest energy subshell. V+: 1s2 2s2 2p6 3s2 3p6 4s1 3d3 V2+: 1s2 2s2 2p6 3s2 3p6 4s0 3d3 V3+: 1s2 2s2 2p6 3s2 3p6 4s0 3d2 V4+: 1s2 2s2 2p6 3s2 3p6 4s0 3d1, which is typically written as 1s2 2s2 2p6 3s2 3p6 3d1 or [Ar] 3d1  Seatwork In a ¼ sheet of paper, give the Long-hand Electron Configuration (expanded), Noble Gas Electron Configuration (shortened) and Orbital Notation/Diagram for the following elements: 1. Ni 2. Ni2+