Week 4 Atoms, Ions and Molecules PDF

PAMANTASAN NG LUNGSOD NG VALENZUELA CIVIL ENGINEERING DEPARTMENT  ARISTOTLE THOMSON BOHR 384-322 BC 1897 1913 THALES DALTON RUTHERFORD CHADWICK LEUCIPPUS 1805 1910...

PAMANTASAN NG LUNGSOD NG VALENZUELA CIVIL ENGINEERING DEPARTMENT  ARISTOTLE THOMSON BOHR 384-322 BC 1897 1913 THALES DALTON RUTHERFORD CHADWICK LEUCIPPUS 1805 1910 1932 DEMOCRITUS THALES OF MILETUS LEUCIPPUS DEMOCRITUS 640 - 546 BC 440 BC 460 - 370 BC He believes all things He made the first recorded All matter is made up of tiny, discrete, come from water. suggestion that matter indivisible, and indestructible consists of separate fundamental units of matter called particles. atoms (from the Greek word Atomos, which means Uncuttable)  He believes that all substances are simply combinations of four principal elements. ARISTOTLE Elements are composed of extremely small particles called atoms that are indestructible and indivisible All atoms of an element are exclusively identical, having the same physical and chemical properties. JOHN DALTON 1805 Compounds are composed of atoms of more than one element. A chemical reaction does not result in the creation or destruction of atom 𝐻 2 + 𝐹2 = 2 𝐻 𝐹 3 𝐻 2 + 1 𝑁2 = 2 𝑁 𝐻 3 𝑁 𝑎𝐻𝐶𝑂 3 Proved by Antoine Lavoisier, it states that the total mass before a chemical reaction is the same as the total mass present after the chemical reaction. 31 g H2O = 3.46g Hydrogen + ____ g Oxygen 8 g H20 = _____g Hydrogen + 7.105 g Oxygen Proved by Antoine Lavoisier, it states that the total mass before a chemical reaction is the same as the total mass present after the chemical reaction. 16𝑔 𝐶𝐻4 + 64 𝑔 2𝑂2 = 44 𝑔 𝐶𝑂2 + __𝑔 𝐻2 𝑂 𝐶𝐻4 + 𝑂2 Published by Joseph Proust, it states that in different samples of same compound the masses of its constituent element will always have the same proportions. 12g C , 32g O 𝐶𝑂2 Atomic Mass 24g C, 64g O C = 12 O = 16 36g C, 96g O 𝐶𝑂2 30g Carbon, g Oxygen? 12g C , 32g O 𝐶𝑂2 25g Carbon, g Oxygen? 12g C , 32g O A pure sample of sodium Fluoride (NaF) contains 35g of Sodium. How many grams of Fluorine are present in this sample? Published by John Dalton, it states that if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in the ratios of small whole numbers. 𝐶𝑂 𝐶 𝑂2  He discovered “corpuscles” (now called electrons) which are particles that are much less massive than the atoms. He proposed the Plum pudding Model, where the atom is a positively charged jelly-like sphere, where J.J THOMSON the negatively charged particles are embedded 1805 within it.  He discovered nucleus, a positively charged particle at the center of the atom. There is a positively charged center in an atom called nucleus. Nearly all the mass of an atom resides in the nucleus. The electrons revolve around the nucleus in circular paths. The size of the nucleus is very small compared to the size of the E. RUTHERFORD atom. 1910 Ernest Rutherford was able to prove that all atoms contain the nucleus of a hydrogen atom. On a later date, the hydrogen nucleus was later named “proton”.  He discovered particles on the nucleus of mass approcimately equal to that of the proton, but without electrical charge - neutrons. J. CHADWICK 1932  Only certain special orbits called discrete orbits of electrons are allowed inside the atom. While revolving in these discrete orbits, the electrons do not radiate energy. NEILS BOHR 1913  a chart in which elements having similar chemical and physical properties are grouped together. The periodic table organizes the elements on a way that you can make predictions about the physical and chemical properties of the element. Is a group of individuals focusing on developing digital standards for chemistry  Metallic elements are good conductors of heat and electricity, they are malleable and ductile. Most metals are solids at room temperature with a characteristic shine Group 1, 1A or IA Alkali metals are so called because their reaction with water forms alkalis (strong bases capable of neutralizing acids) Group 2, 2A or IIA (Prior to 19th Century, substances that were nonmetalic, insoluble in water and unchanged by fire were known as earths) The metals whose oxides make up the alkaline earths. Non-metal elements are (usually) poor conductors of heat and electricity and are not melleable and ductile. Many non metals are gases at room temperature, while others vary from liquids to solids. Group 17 (7A or VIIa) From the Greek roots hal- (salt) and -gen (to produce), they are elements that produce sodium salts of similar properties. Group 18 (8A or VIIIa) The noble gases are colorless, odorless, tasteless, non- flammable inert gases. They are also the only elements that exist in nature as single atoms Metalloids have properties that are intermediate between those of metals and nonmetals. In their physical properties, they are more like the nonmetals, but under certain circumstances, several of them can be made to conduct electricity. Equal to the number of protons. The chemical identity of an atom can be determined solely by its atomic number. It is the total number of neutrons and protons present in the nucleus of an atom of an element. The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance. (amu/atomic mass unit, unit for average atomic mass, 1 amu = 1.6605 x 10^-27kg) Atoms of the same element with different number of neutrons in their nuclei Copper, a metal known since ancient times, is used in electrical cables and 63 65 pennies. The atomic masses of its two isotopes 29 Cu and 29 Cu are 62.9296amu and 64.9278amu, respectively. The natural abundance of copper-63 and copper-65 are 69.152% and 30.848%. Calculate the average atomic mass of copper Chlorine has two isotopes. Chlorine-35 has an actual mass of 34.9689 amu and chlorine-37 has a mass of 36.9659 amu. In any sample of chlorine atoms, 75.771% will be chlorine-35 and 24.229% will be chlorine 37. Calculate the average atomic mass of chlorine. An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99amu, 0.26% abundance with 20.99amu, and 8.82% abundance with 21.99amu. What element is it most probable? # of protons = atomic number # of neutrons = mass number – atomic number # of electron = atomic number - charges # of protons = atomic number # of neutrons = mass number – atomic number # of electron = atomic number – charges Practice Exercises: 79 2− 𝑆𝑒 # of protons = atomic number # of neutrons = mass number – atomic number # of electron = atomic number – charges Practice Exercises: 79 2− 𝑆𝑒 39 + 𝐾 Chemists use chemical formulas to express the composition of molecules in compounds in terms of chemical symbols (Element present and ratios in which the atoms are combined) Since we cannot observe molecules directly, we use effective means of visualizing them using molecular models Atoms of the same element with different number of neutrons in their nuclei Shows the simplest whole number ratio of the atoms in a substance Write the empirical formulas for the following molecules: a) acetylene (𝐶2 𝐻2 ), which is used in welding torches Write the empirical formulas for the following molecules: a) acetylene (𝐶2 𝐻2 ), which is used in welding torches b) glucose (𝐶6 𝐻12 𝑂6 ), a substance known as blood sugar are aggregates of at least two atoms in a definite arrangement held together by chemical forces. (Chemical Forces = Chemical Bonds) are not molecules, for they consist of single atom only. are molecules that contain specifically two atoms. 𝐻2 , 𝑁2 , 𝑂2 , 𝐹2 , 𝐶𝑙 2 , 𝐵𝑟2 , 𝐼2 Hydrogen Chloride (HCI) Carbon Monoxide (CO) Sodium Chloride (NaCl) are molecules containing more than two atoms Ozone ( 𝑂3 ) Water ( 𝐻2 𝑂) Ammonia ( 𝑁𝐻3 ) is one of two or more distinct forms of an element Ozone ( 𝑂3 ), 𝑂𝑥𝑦𝑔𝑒𝑛 ( 𝑂2 ) Graphite, Diamond are atoms, or group of atoms, that have a net positive or negative charge. Ion with a positive charge. If a neutral atom loses one or more electrons, it becomes a cation. Ion with a negative charge. If a neutral atom gains one or more electrons, it becomes a anion. ion that contain only one atom + − 2+ 2− 3+ 3− 𝑁𝑎 , 𝐶𝑙 , 𝐶𝑎 ,𝑂 , 𝐴𝑙 ,𝑁 ions that contain more than one atom − − + − 𝑂𝐻 , 𝐶𝑁 , 𝑁𝐻4 , 𝑁𝑂3 are compounds formed between a metal cation and a nonmetal anion. The formulas for ionic compounds are usually the same as their empirical formulas. For Ionic Compounds to be electrically neutral, the sum of the charges on the cation and anion in each formula must be zero. Most reactive metals (Red) and most reactive non metals (green) combine to form ionic compounds. Write the chemical formula of the following ionic compounds 1. Potassium bromide (𝐾 , 𝐵𝑟 )+ − 2. Zinc iodide (𝑍𝑛 2+ , 𝐼 − ) 3. Aluminum oxide (𝐴𝑙 , 𝑂 )3+ 2− It is the practice of naming chemical compounds. Generally, chemical nomenclature is divided into two categories: contains carbon, usually in combination with elements such as hydrogen, oxygen, nitrogen and sulfur all other compounds not classified as organic Compounds formed between a metal cation and a nonmetal anion. - Anion (nonmetal), add “ide” to element name. Name of Cation + Name of Anion Determine the systematic name of the following compounds: 1. 𝐵𝑎𝐶𝑙2 2. 𝐾2 𝑂 3. 𝑀𝑔(𝑂𝐻)2 Molecular or covalent compounds are usually composed of nonmetallic elements. prefix–first element + prefix–second element–ide Determine the systematic name of the following compounds: 1. 𝑆𝑂2 2. 𝑁2 𝑂4 3. 𝐴𝑠2 𝑂5 Stock System is used for naming compounds that contains a multivalent metal (a metal that can form more than one type of ion). Charge of the metal is indicated by roman numerals. name of cation(charge of cation in r.n.) + name of anion Determine the systematic name of the following compounds: 1. 𝑀𝑛2+ 2. 𝑀𝑛3+ 3. 𝑀𝑛4+ Acids can be defined as a substance that yields hydrogen ions (H+) when dissolved in water. Since all acids contain hydrogen, the name of an acid is based on the anion of the compound. There are two general classifications of acids: 1.Binary Acids 2.Oxyacids A binary acid is an acid that consists of hydrogen and one other element. hydro–base name of non-metal–ic + acid Determine the systematic name of the following compounds: 1. HCl 2. 𝐻2 𝑆 3. HCN A binary acid is an acid that consists of hydrogen and one other element. hydro–base name of non-metal–ic + acid Determine the systematic name of the following compounds: 1. HCl 2. 𝐻2 𝑆 3. HCN Acids that contain oxyanions(anions that contain oxygen). if oxyanion ends in –ite base name of oxyanion–ous + acid if oxyanion ends in –ite with one atom of oxygen removed hypo–base name of oxyanion–ous + acid if oxyanion ends in –ate with one atom of oxygen added per–base name of oxyanion–ic + acid Acids that contain oxyanions(anions that contain oxygen). Determine the systematic name of the following compounds: 1. 𝐻𝑁𝑂2 2. 𝐻𝐵𝑟𝑂 3. 𝐻𝐶𝐼𝑂4 Acids that contain oxyanions(anions that contain oxygen). Determine the systematic name of the following compounds: 1. 𝐻𝑁𝑂2 2. 𝐻𝐵𝑟𝑂 3. 𝐻𝐶𝑙𝑂4 Bases can be defined as a substance that yields hydroxide ions (OH−) when dissolved in water. name of cation + hydroxide Determine the systematic name of the following compounds: 1. 𝑁𝑎𝑂𝐻 2. 𝐾𝑂𝐻 3. 𝐵𝑎(𝑂𝐻)2 Hydrates are compounds with molecules that have a specific number of water molecules attached to them name of cation + name of anion + prefix–hydrate Determine the systematic name of the following compounds: 1. 𝐵𝑎𝐶𝑙2 · 2𝐻2 𝑂 2. 𝐿𝑖𝐶𝑙 · 2𝐻2 𝑂 3. 𝑀𝑔𝑆𝑂4 · 7𝐻2 𝑂 Hydrocarbons are the simplest type of organic compounds, which contains only hydrogen and carbon atoms. They are used as fuels for generating electricity, heat source, and to power combustion engines. There are three general classifications of hydrocarbons. 1. Aliphatic hydrocarbons – form straight chains 2. Alicyclic hydrocarbons – form rings of carbon atoms 3. Aromatic hydrocarbons – contains special structure called a benzene ring (C6H6 ) The nomenclature of hydrocarbons requires the knowledge of the molecule’s structural formula.  1.The first part of the name is based on the length of the longest carbon chain in the molecule. (longest carbon chain = main chain) 2.Number the carbon atoms in the main chain starting from the end closest to the greatest number of bonds or branch 3.The end of the name is given by the number of bonds between carbon atoms. Single bonds –ane at least one double bond –ene at least one triple bond –yne 4. If there are branches, name the branch chain then attach it as a prefix of the main chain with its location. (prefix–yl) Note: comma is used between numbers, dashes are used between letter to number