MODULE 1 UNIT 3.pdf

INCHEM 211 Department of Chemical Engineering Proper...

INCHEM 211 Department of Chemical Engineering Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  MODULE 1: FOUNDATIONS OF CHEMISTRY UNIT THREE - CHEMICAL SYMBOLS, NOTATIONS & NOMENCLATURE ENGAGE ENGAGE ENGAGE ENGAGE ENGAGE ENGAGE VOCABULARY OF CHEMISTRY If you’re studying chemistry, you may have been alarmed when you saw a string of letters and numbers linked together. What in the world does NaOH, Ca2+ and carbon – 14 mean? Although it can look confusing, it isn’t so bad. You just have to learn how to read chemistry! This lesson will go through all the basic nomenclature and notations so you will be ready to tackle any chemistry that comes your way. The names and formulas of compounds are essential vocabulary in chemistry. The naming of substances is called chemical nomenclature from the Latin words nomen (name) and calare (to call). There are now over 13 million known chemical substances. Naming them all would be a hopelessly complicated task if each had a special name independent of all others. Many important substances that have been known for a long time, such as water, H2O, and ammonia, NH3, do have individual, traditional names. For most substances, however, we rely on a systematic set of rules that lead to an informative and unique name for each substance, based on its composition. The rules for chemical nomenclature are based on the division of substances into different categories. The major is between organic compounds and inorganic ones. Organic compounds usually contain carbon, usually in combination with hydrogen, oxygen, nitrogen or sulphur. All other compounds are called inorganic compound. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  EXPLORE EXPLORE EXPLORE EXPLORE EXPLORE EXPLORE In this module, we consider the basic rules for naming inorganic compounds. But before we proceed with naming chemical substances, we must familiarize ourselves with elements, compounds (the first two are already introduced in Unit 1), isotopes and more. ELEMENTS Let’s first start with an element, a substance that cannot be broken down into new substances. At the present time, 118 elements are known. These elements vary widely in their abundance. For example, over 90% of Earth’s crust consists of only five elements: oxygen, silicon, aluminium, iron and calcium. In contrast, just three elements (oxygen, carbon and hydrogen) C account for over 90% of the mass of the human body. Carbon The table in which the symbol for each element is enclosed in a box is called the periodic table. In the periodic table, the elements are arranged in vertical columns so that closely related elements are grouped together. Before proceeding to the next topic, try to take a grasp at the periodic table and be familiarized with the symbols of some elements. NOTE: A soft copy of the period table is saved on the provided memory stick. ISOTOPES An atom is the smallest part of an element that still keeps the properties of that element. Each atom is made up of protons (positively charged) and neutrons (has no charge), which reside in a nucleus, and electrons (negatively charged), which can be found outside of the nucleus (discussed from Unit 1). The number of protons in an atom determines the atom's identity and can be found on the periodic table. This number is called the atomic number. For example, all hydrogen atoms have one proton; all lithium atoms have three protons and so on. The number of protons and neutrons together is the mass number and can also be found on the periodic table. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  Let’s take Carbon as an example. From the figure (left), the number located at the top right indicates the atomic number (number of protons). Meanwhile, the figure below the name of the element (12.011 or can be simplified as 12) refers to the atomic mass. Let’s take another example: Carbon – 12 and Carbon – 14. Are these two the same? The numbers 12 and 14 represent the atomic mass. We already know that the naturally occurring carbon has an atomic mass of 12 (from the periodic table). What about Carbon – 14? This substance is an isotope. Atoms of a given element that differ in the number of neutrons, and consequently in mass, are called isotopes. Always remember that the atomic number (number of protons) does not change. That explains why it indicates the identity of an atom. From the example, the naturally occurring carbon is Carbon – 12. Therefore, it has 6 protons and 6 neutrons (12 – 6 = 6). On the other hand, Carbon – 14 has 6 protons and 8 neutrons (14 – 6 = 8). To understand further, let’s solve this problem: How many protons and neutrons are in an atom of Au – 197? Answer: The figure 197 is the mass number, the sum of the numbers of protons and neutrons. From the periodic table, the atomic number of Au (gold) is 79. Consequently, it has 118 neutrons (197 – 79). EXERCISE NO. 1 To test yourself, answer what is asked. Correct answers are found at the end of this module. How many protons and neutrons are in a K – 39 atom? Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  COMPOUNDS Most elements can interact with other elements to form compounds. Hydrogen gas for example, burns in oxygen gas to form water. O H H A structure of water molecule Another example is oxygen that is normally found in air. It consists of two oxygen atoms. We represent this molecular form of oxygen by the chemical formula O2. The subscript tells us that two oxygen atoms are present in each molecule. IONS AND POLYATOMIC IONS If you notice from our practice problems on isotopes, the number of electrons is not asked. In this section, we are able to include the role of electrons to some types of compounds. The nucleus of an atom is unchanged by ordinary chemical processes, but atoms can readily gain or lose electrons. If electrons are removed or added to a neutral atom, a charged particle called an ion is formed. An ion with a positive charge is called a cation (higher number of protons); a negatively charged ion is called an anion (higher number of electrons). For example, the sodium atom, which has 11 protons and 11 neutrons, easily loses one electron. The resulting cation has 11 protons (positive charge) and 10 electrons (negative charge), and hence, a net charge of 1+ (11 + -10 = 1). The Net charge on an ion is represented by a superscript; +, 2+ and 3+ mean a net charge resulting from the loss of one, two or three electrons respectively. Thus, a sodium ion that lost 1 electron can be represented as Na+. In addition to simple ions such as Na+ and Cl-, there are polyatomic ions such as NO3- and SO42-. These ions consist of atoms joined as in a molecule, but they have a net positive or negative charge. Let’s go back to the last practice problem: Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  How many protons, ELECTRONS and neutrons are in an atom of Au – 197? Answer: The figure 197 is the mass number, the sum of the numbers of protons and neutrons. From the periodic table, the atomic number of Au (gold) is 79 and this will be the number of protons.. Consequently, it has 118 neutrons (197 – 79). In addition, Au – 197 does not have any positive or negative charge (not an ion). Thus, it is a NEUTRAL atom. When we say neutral, the numbers of protons and electrons are equal. When we are going to add these two (numbers of protons and electrons), the sum will be ZERO. Thus, the number of electrons is still 79. So that’s it. We are able to familiarize ourselves with the following: elements, isotopes, compounds, ions and polyatomic ions. EXPLAIN EXPLAIN EXPLAIN EXPLAIN EXPLAIN EXPLAIN NAMING PART A: ELEMENTS Each element is represented on the periodic table by a symbol, usually one or two letters that makes it easily identifiable. These symbols may be a single capital letter or a capital letter followed by a lowercase letter. Occasionally you may see an element with a capital letter followed by lowercase letters. Sometimes the symbols make sense. For example, you can see why calcium has the symbol Ca, right? But other times it's not as clear. You may be wondering why sodium has the symbol Na. Many of the symbols come from a Latin origin of the element; for example, the Latin word for sodium is natrium and this is where the symbol comes from. EXERCISE NO. 2 Provide the naming of the following chemical symbols using the periodic table: a. Fe f. Yb b. Tl g. Er c. Pd h. Es Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  d. W i. Dy e. Hf j. Bk PART B: ISOTOPES Like elements, isotopes are easy to represent as well. Let’s go back to our previous example which is Carbon – 14. This isotope can be represented as: The upper left number always refers to C 14 the atomic mass while the figure at the lower left indicates the atomic number. Lastly, C indicates the chemical formula of the element which is carbon. From the figure (left) alone, we 6 can conclude that it is a carbon isotope with atomic mass of 14 and it has 6 protons, 6 electrons (a neutral atom) and 8 neutrons. ꯸th Let’s take another example: ꯸. From the periodic table, it is an isotope for uranium. It has an atomic number of 92. Therefore, there are 92 protons as well as electrons since it is a neutral atom (it has equal number of protons and electrons). Then, the atomic mass is 238 making the number of neutrons as 146. EXERCISE NO. 3 Fill in the gaps in the following table assuming each column represents a neutral atom: Symbol 46 Ti 22 Protons 45 Neutrons 58 18 50 Electrons 16 52 Atomic Number 38 Mass Number 127 PART C: POSITIVE IONS (CATIONS) a. Cations formed from metal atoms have the same name as the metal: Na+ sodium ion Zn2+ zinc ion Al3+ aluminium ion Ions formed from a single atom are called monoatomic ions. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  b. If a metal can form cations of differing charges, the positive charge is given by a Roman numeral in parenthesis following the name of the meta, this method is called the stock method: Fe2+ iron (II) ion Cu+ copper (I) ion Fe3+ iron (iii) ion Cu2+ copper (II) ion Ions with different charges exhibit different properties, such as color. An older method still widely used for distinguishing between two differently charged ions of a metal, called the classical method, is to apply the ending – ous or –ic. These endings represent the lower and higher charged ions, respectively. They are added to the root of the element’s Latin name: Fe2+ ferrous ion Cu+ cuprous ion Fe3+ ferric ion Cu2+ cupric ion PART D: NEGATIVE IONS (ANIONS) a. Monoatomic anions have names formed by dropping the ending of the name of the element and adding the ending –ide. H− hydride ion O2− oxide ion N3− nitride ion A few simple polyatomic anions also have names ending in –ide: OH− hydroxide ion CN− cyanide ion O2− 2 peroxide ion b. Polyatomic anions containing oxygen have names ending in –ate or –ite. These anions are called oxyanions. The ending –ate is used for the most common oxyanion of an element. The ending –ite is used for an oxyanion that has the same charge but less O atom: NO2− 3 nitrate SO2− 4 sulfate NO−2 nitrite SO32− sulfite Prefixes used when series of oxyanions of an element extends to four members, as with the halogens. The prefix per- indicates one more O atom than the oxyanion ending in-ate; the prefix hypo- indicates one less O atom than the oxyanion ending in –ite: ClO− 4 Perchlorate (one more O than chlorate) ClO− 3 Chlorate ion ClO− 2 Chlorite ion (one less O than chlorate) Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  ClO− Hypochlorite (one less O than chlorite) c. Anions derived by adding H+ to an oxyanion are named by adding as a prefix the word hydrogen, or dihydrogen, as appropriate: CO2− 3 carbonate ion PO3− 4 phosphate ion − − HCO3 hydrogen carbonate ion H2 PO4 dihydrogen phosphate ion IMPORTANT NOTE: To easily name any ion or even ionic compound, you can always refer to the table of ions. The table is already saved on the memory stick provided with file names Module 1 Unit 3 - List of Common Ions and Module 1 Unit 3 - List of Common Ions Part 2. PART E: IONIC COMPOUNDS Names of ionic compounds are the cation name followed by the anion name: BaBr2 Barium bromide Al NO3 3 Aluminium nitrate Cu ClO4 2 Copper (II) perchlorate (cupric perchlorate) Notice how parentheses are used in writing the chemical formulas for aluminium nitrate and copper (II) perchlorate. Parentheses followed by the appropriate subscript are used when a compound contains two or more polyatomic ions. If you are wondering how come copper (II) is used since there is copper (I), the answer is found at the third example from the next problem. To understand further, here are other sample problems: Name the following compounds: (a) K2SO4; (b) Ba(OH)2; (c) FeCl3 Answer: (a) The cation in this compound is K+, and the anion is SO42-. If you thought the compound contained S2- and O2- ions, you failed to recognize the polyatomic sulfate ion. Putting together the names of the ions, we have the name of the compound, potassium sulphate. (b) In this case the compound is composed of Ba2+ and OH- ions. Ba2+ is the barium ion and OH- is the hydroxide ion. Thus, the compound is called barium hydroxide. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  (c) You must determine the charge of Fe in this compound because iron can have variable charges. Because the compound contains three Cl- ions, the cations must be Fe3+, which is called the iron (III) or ferric ion. The Cl- ion is called the chloride ion. Thus, the compound is iron (III) chloride or ferric chloride. EXERCISE NO. 4 Name the following compounds: a. NH4Br b. Cr2O3 c. Co(NO3)2 PART F: INORGANIC ACIDS Acids are an important class of hydrogen – containing compounds and are named a special way. For our present purposes, an acid is defined as a substance whose molecules yield hydrogen ions (H+) when dissolved in water. When we encounter the chemical formula for an acid at this stage of the course, it will be written with H as the first element, as in HCl and H2SO4. a. Acids based on anions whose names end in –ide. Anions whose names end in –ide have associated acids that have the hydro – prefix and an –ic ending as the following examples: Anion Corresponding Acid Cl (chloride) - HCl (hydrochloric acid) S2- (sulphide) H2S (hydrosulfuric acid) b. Acids based on anions whose names end in –ate or –ite. Anions whose names end in –ate have associated acids with an –ic ending, whereas anions whose names end in –ite have acids with and –ous ending. Prefixes in the name of the anion are retained in the name of the acid. These rules are illustrated by the oxyacids of chlorine: Anion Corresponding Acid ClO- (hypochlorite) HClO (hypochlorous acid) ClO2- (chlorite) HClO2 (chlorous acid) ClO3- (chlorate) HClO3 (chloric acid) ClO4- (perchlorate) HClO4 (perchloric acid) Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  EXERCISE NO. 5 Name the following acids: a. HCN b. HNO3 c. H2SO4 d. H2SO3 Give the chemical formulas for: a. Hydrobromic acid b. Carbonic Acid PART G: BINARY MOLECULAR COMPOUNDS The procedures used for naming binary (two-element) molecular compounds are similar to those used for naming ionic compounds: a. The name of the element farthest to the left in the periodic table is usually written first. b. If both elements are in the same group in the periodic table, the lower one is named first. 3. The name of the second element is given an –ide ending. 4. Greek prefixes (table below) are used to indicate the number of atoms of each element. The prefix mono- is never used with the first element. When the prefix ends in a or o and the name of the second element begins with a vowel (such as oxide), the a or o is often dropped. Prefix Meaning Mono- 1 Di- 2 Tri- 3 Tetra- 4 Peta- 5 Hexa- 6 Hepta- 7 Octa- 8 Nona- 9 Deca- 10 Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  The following examples illustrate these rules: Cl2O Dichlorine monoxide NF3 Nitrogen trifluoride N2O4 Dinitrogen tetroxide P4S10 Tatraphosphorus decasulfide EXERCISE NO. 6 Name the following compounds: a) SO2; b)PCl5; c) N2O3 Give the chemical formula for a) silicon tetrabromide; b)disulfur dichloride ELABORATE ELABORATE ELABORATE ELABORATE Formative Assessment (Graded Assignment) 1. Given the name of the compound (on the left), correct the provided chemical formula (on the right): a) Sodium sulfate - NaSO4 b) Sulfur hexafluoride - S6F c) Sodium hydroxide - Na(OH)2 d) Iron(III) oxide - Fe3O e) Carbonic acid - H2(CO)3 2. Given the chemical formula of the compound (on the left), correct the provided chemical name (on the right): a) Fe3(PO4)2 - Iron(III) phosphite b) HNO2 - Nitric acid c) P2O5 - Phosphorous pentaoxide d) KCN - Potassium carbon nitide e) SiCl4 - Silicon tetrachlorate 3. Complete the table below: Symbol 37 17 Cl 14 N 7 Protons 22 Neutrons 7 Electrons 17 Atomic Number 17 Mass Number 47 14 Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  EVALUATE EVALUATE EVALUATE EVALUATE You have reviewed some important concepts for Chemical Nomenclature and acquired additional and new knowledge on some important advancement. You should be able to apply these concepts. Module 1 Evaluative Assessment on DATE via Google Classroom References: Brown, Le May & Bursten. (1997). Chemistry, The Central Science, 7th Ed. USA: Prentice Hall International. ANSWERS TO EXERCISES: EXERCISE NO. 1: K – 39 Number of proton = 19 Number of neutron = 20 EXERCISE NO. 2: a. Iron e. Hafnium h. Eisteinium b. Thallium f. Ytterbium i. Dysprosium c. Palladium g. Erbium j. Berkelium d. Tungsten EXERCISE NO. 3: Symbol 46 103 34 127 88 22 Ti 45 Rh 16 S 52 Te 38 Sr Protons 22 45 16 52 38 Neutrons 24 58 18 75 50 Electrons 22 45 16 52 38 Atomic Number 22 45 16 52 38 Mass Number 46 103 34 127 88 Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  EXERCISE NO. 4: Ammonium Bromide Chromium (III) Oxide Cobalt (II) Nitrate EXERCISE NO. 5: Hydrocyanic acid Nitric acid Sulphuric acid Sulphurous acid HBr H2CO3 EXERCISE NO. 6: Sulfur dioxide Phosphorus pentachloride Dinitrogen trioxide SiBr4 S2Cl2 Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.