BMCI Week 1 Lecture 1: Compounds, Mixtures, Chemical Formulas and Naming Compounds PDF

Matter: Elements Mixtures and chemical compounds Chemical formulas Naming chemical compounds BMCI 2024 Bálint Bécsi Classification of matter A fundamental substance that cannot be broken down chemically into any sim...

Matter: Elements Mixtures and chemical compounds Chemical formulas Naming chemical compounds BMCI 2024 Bálint Bécsi Classification of matter A fundamental substance that cannot be broken down chemically into any simpler substance. Chemistry and the Elements  Chapter 1/4 Elements and the Periodic Table Main Groups columns 1A–2A (2 groups) columns 3A–8A (6 groups) Transition Metals: 3B–2B (8 groups, 10 columns) Inner Transition Metals: 14 groups between 3B and 4B lanthanides actinides © 2012 Pearson Education, Inc.  Chapter 1/5 Elements and the Periodic Table Main Groups columns 1A–2A (2 groups) columns 3A–8A (6 groups) Transition Metals: 3B–2B (8 groups, 10 columns) Inner Transition Metals: 14 groups between 3B and 4B lanthanides actinides © 2012 Pearson Education, Inc.  Chapter 1/6 Elements and the Periodic Table Main Groups columns 1A–2A (2 groups) columns 3A–8A (6 groups) Transition Metals: 3B–2B (8 groups, 10 columns) Inner Transition Metals: 14 groups between 3B and 4B lanthanides actinides © 2012 Pearson Education, Inc.  Chapter 1/7 Some Chemical Properties of the Elements All react rapidly, often violently, with water to form products that are highly alkaline, or basic—hence the name alkali metals. Because of their high reactivity, the alkali metals are never found in nature in the pure state but only in combination with other elements. © 2012 Pearson Education, Inc.  Chapter 1/8 Some Chemical Properties of the Elements All are also lustrous, silvery metals but are less reactive than their neighbours in group 1A. Like the alkali metals, the alkaline earths are never found in nature in the pure state. © 2012 Pearson Education, Inc.  Chapter 1/9 Some Chemical Properties of the Elements Halogens are colorful, corrosive nonmetals. They are found in nature only in combination with other elements, such as with sodium in table salt (sodium chloride, NaCl). In fact, the group name halogen is taken from the Greek word hals, meaning “salt.” © 2012 Pearson Education, Inc.  Chapter 1/10 Some Chemical Properties of the Elements Noble gases are colorless gases with very low chemical reactivity. Helium and neon don’t combine with any other element; argon, krypton, and xenon combine with very few. © 2012 Pearson Education, Inc.  Chapter 1/11 Some Chemical Properties of the Elements Metals: Left side of the zigzag line in the periodic table (except for hydrogen) Properties of the Metals Metals are typically solids with high melting points and high densities and have a bright, metallic luster. Metals are good conductors of heat and © 2012 Pearson Education, Inc. electricity. Metals are also ductile and malleable.  Chapter 1/12 Some Chemical Properties of the Elements Nonmetals: Right side of the zigzag line in the periodic table Properties of the Nonmetals Nonmetals typically have low melting points and low densities and have a dull appearance. Nonmetals are poor conductors of heat and electricity. Nonmetals are not malleable or ductile and crush into a powder when hammered. © 2012 Pearson Education, Inc.  Chapter 1/13 Some Chemical Properties of the Elements Semimetals (metalloids): Tend to lie along the zigzag line in the periodic table Properties of the Semimetals Semimetals typically exhibit properties of both metals and nonmetals. – For example: Silicon is a semiconductor and will only conduct electricity under some conditions. © 2012 Pearson Education, Inc. Classification of matter  Pure Substances Elements Compounds Cl2(g) HCl(g) Pure substances…  cannot be separated into two or more substances by physical methods.  are homogeneous, they have uniform composition throughout the whole sample.  have constant chemical composition.  their properties are constant throughout the whole sample.  Pure Substances Elements…  consist of only one kind of atom (same atomic number).  cannot be decomposed by CHEMICAL means.  can exist as either atoms (e.g. Ar) or molecules (e.g., N2).  are ’building blocks' of the universe.  are abbreviated by symbols.  Pure Substances Compounds…  consist of atoms of two or more different elements bound together.  can be decomposed by chemical means to elements/other compounds.  All samples of a compound will have the same elements in the same ratio.  Mixtures A mixture is a blend of two or more substances in some arbitrary proportion.  Mixtures A mixture…  can be separated into two or more substances by physical or mechanical means.  displays the properties of the pure substances making it up.  its composition can be varied by changing the proportion of pure substances making it up. 3:4 7:2  Separation of Mixtures based on different physical properties of the components. Different Physical Property Technique Boiling Point Distillation State of Matter (solid/liquid/gas) Filtration Adherence to a Surface Chromatography Volatility Evaporation Distillation is an effective method to separate mixtures comprised of two or more pure liquids. The mixture is heated and the most volatile component vaporizes at the lowest temperature. The vapor passes through a cooled tube, where it condenses back into its liquid state. Evaporation is a technique used to separate out homogenous mixtures where there is one or more dissolved solids. This method drives off the liquid components from the solid components. In many parts of the world, table salt is obtained from the evaporation of sea water. The heat for the process comes from the sun. Filtration is a separation method used to separate out pure substances in mixtures comprised of particles some of which are large enough in size to be captured with a porous material. Some water filters can filter out bacteria, the length of which is on the order of 1 micron. Other mixtures, like soil, have relatively large particle sizes, which can be filtered through something like a coffee filter. The crystalline quartz sand is a pure compound (SiO2) but the seawater is a liquid mixture of many compound dissolved in water.  Types of mixtures Particles distributed Particles distributed non-uniformly uniformly A heterogeneous mixture has A homogenous mixture has the components whose proportions vary same proportions of its components throughout the sample. throughout any given sample. Within the categories of homogeneous and heterogeneous mixtures there are more specific types of mixtures including solutions, alloys, suspensions, and colloids.  Homogeneous mixtures  Can NOT see the different parts of the mixture.  Solutions are homogeneous mixtures.  Although liquid solutions are most common, solutions can exist in the gaseous and solid states as well. Air is homogeneous mixture of invisible odorless tasteless gases (such as nitrogen and oxygen) that surrounds the earth. An alloy is a mixture of elements that has the characteristic of a metal. At least one of the elements mixed is a metal. One example of an alloy is steel which is made from a mixture of iron and carbon. Seawater is a liquid mixture.  Heterogeneous mixtures  Particles are big enough to see and will settle out.  A suspension is a mixture between a liquid and particles of a solid. A key characteristic of a suspension is that the solid particles will settle and separate over time if left alone.  Examples: pizza oil in water sand in water sand and oil in water Classification of Matter  Matter Flowchart Pure substance  Atoms and Molecules On the microscopic level, matter consists of atoms and molecules.  In a molecule, the atoms are joined together by covalent bonds.  Molecules may consist of the same or different types of atoms.  Nonmetal/nonmetal  Neutral (no charge)  Molecular models A molecule is the smallest unit of a compound that retains the chemical characteristics of the compound. Ball-and-stick models show atoms (spheres) joined together by covalent bonds (sticks). Space-filling models portray the overall molecular shape but don’t explicitly show covalent bonds. Hydrogen chloride Water Ammonia Methane (HCl) (H2O) (NH3) (CH4) Some elements exist as molecules P4 S8  IONS IONS are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom gives a CATION with a positive charge Adding an electron to an atom gives an ANION with a negative charge.  Forming Cations and Anions H+ H H⁻ 1 proton 1 proton 1 proton 1 electron 2 electrons  Forming Cations and Anions Mg  Mg2+ + 2 e- F + e-  F- 12 protons 12 protons 9 protons 9 protons 12 electrons 10 electrons 9 electrons 10 electrons Metals tend to form Nonmetals tend to form cations. anions.  Predicting Ionic Charge The number of electrons an atom loses or gains is related to its position on the periodic table. Metals tend to form cations whereas non-metals tend to form anions.  Predicting Ionic Charge Main-group metals usually form cations whose charge is equal to the group number. Main-group nonmetals usually form anions whose charge is equal to the group number minus 8. Some transition metals form more than one cation  Chemical compounds Covalent and ionic bonds  Compounds and Chemical Bonds Formation of a chemical compound (example) H2 + Cl2 2 HCl Chemical bonds join atoms together. Compounds can be classified based on the types of bonds that they contain.  Chemical Bonds Covalent Bond:  results when two atoms share several (usually two) electrons  typically a nonmetal is bonded to a nonmetal Molecule: Ionic Bond: Molecule: the unit of matter that results when two or more atoms are joined by covalent bond  Chemical Bonds Ionic Bond  transfer of one or more electrons from one atom to another  strong electrical attraction between charged particles  typically a metal bonded to a nonmetal. Ion: A charged particle Cation: A positively charged particle. Metals tend to form cations. Anion: A negatively charged particle. Nonmetals tend to form anions.  Ionic Compounds In the formation of sodium chloride, one electron is transferred from the sodium atom to the chlorine atom. 1 Na + 2 Cl2 Na+ + Cl-  Pure Substances: Types of Compounds Pure Substances If the electrons are If the electrons are transferred, these mutually shared, Elements compounds are these compounds called ionic are called Covalent Compounds compounds. Compounds. Molecules Ionic Covalent Compounds Sharing electrons transfer electrons non-metals metal + nonmetal Polar- Covalent unequal sharing electrons If the electrons are unequally shared, metals or non-metals then these are called polar covalent compounds. Chemical formula: a format for listing the number and kinds of constituent elements in a compound. The chemical formula for a covalent compound is called a molecular formula. E.g., H2O is the molecular formula of water The chemical formula for an ionic compound is called a formula unit. NaCl is the formula unit of common table salt  Picturing Molecules Name Molecular formula Structural formula Acetic acid C2H4O2 A structural formula gives the connectivity between individual atoms in a molecule. Molecular model: Molecular model: ’’ball and stick’’ ’’space-filling’’ Molecules have three-dimensional shape. However, we often represent them in two dimensions.  Picturing Molecules Methane, CH4 Structural formula gives the connectivity between individual atoms in the molecule. Perspective drawings use dashed lines and wedges to represent bonds receding and emerging from the plane of the paper. Ball-and-stick models show atoms as contracted spheres and the bonds as sticks. The angles in the ball-and-stick model are accurate. Space-filling models give an accurate representation of the 3D shape of the molecule. Give molecular formulas corresponding to each of the following ball- and-stick molecular representations (red=O, gray=C, blue=N, ivory=H). In writing the formula, list the atoms in alphabetical order. Alanin (an amino acid) C3H7NO2 Ethylene glycol C2H6O2 (automobile antifreeze) Ionic Compounds and Formula Units Sodium chloride exists as a crystal:  Ionic Compounds and Formula Units  NaCl does not exist as a single unit like a molecule.  The Na+ and Cl- ions are each bonded to six oppositely charged neighbors.  The ratio of Na+ and Cl- ions is 1:1.  NaCl is a binary compound, which contains only two different elements.  The formula unit for sodium chloride is NaCl. The chemical formula for an ionic compound is called a formula unit. The formula unit, shows the lowest whole number ratio of the ions, is an empirical formula.  Ionic Compound Formulas  The symbol for the positive element is written first, followed by the symbol of the negative element  Subscripts are used to indicate the numbers of ions needed to produce an electrically neutral compound.  cation charges   anion charges  Ionic Compound Formulas Ionic Compound: A neutral compound in which the total number of positive charges must equal to the total number of negative charges. Principle of electrical neutrality is applied in order to predict formulas of ionic compound. Example 1: Potassium and Fluorine K K+ KF F F - Potassium and fluorine combine in a 1:1 ratio because potassium (K) is positive one (+1) and fluorine (F) is negative one (-1). Only in a 1:1 combination will the charges cancel each other.  Ionic Compound Formulas Example 2: Aluminum and Sulfur +3 Al Al +3 -2 Al S -2 Al S S 2 3 S Aluminum and sulfur combine in a 2 : 3 ratio because aluminum (Al) is positive three (+3) and sulfur (S) is negative two (-2). Only in a 2:3 combination will the charges cancel each other. What will be the formula for the ionic compound formed between Mg and N? Magnesium and nitrogen combine in a 3 : 2 ratio because magnesium (Mg) is positive two (+2) and nitrogen (N) is negative three (-3). Only in a 3:2 combination will the charges cancel each other. Mg3N2 In the following drawings, red spheres represent cations and blue spheres represent anions. Match each of the drawings (a)-(d) with the following ionic compounds: Ca3(PO4)2 MgSO4 Li2CO3 FeCl2 MgSO4 Li2CO3 FeCl2 Ca3(PO4)2  Naming Compounds Common Names Examples: table salt, quicklime, barbituric acid  Arbitrary – Not based on chemical composition – Not consistent among languages or disciplines Systematic names – Identify the chemical composition – Devised by IUPAC NaCl, CaO  Naming Compounds Inorganic compounds  Binary ionic compounds  Binary molecular compounds  Compounds with polyatomic ions  Acids  Naming Binary Ionic Compounds Binary ionic compounds are named by naming the metal ion (cation) first, followed by the nonmetal ion (anion). KF Identify the positive ion and the Al2S3 negative ion. Give their name. BaCl2 Fe2O3  Naming the Ions Names of main-group monatomic ions are straightforward. A cation takes the name of the element plus the word "ion." K+ Al3+ Ba2+ potassium ion aluminum ion barium ion If the metal can form more than one cation, then the charge is indicated in parentheses in the name. Cu+ copper(I) ion Cu2+ copper(II) ion Cations formed from non-metals end in -ium. NH4+ ammonium ion Naming cations  Naming anions Monatomic anions: stem of element name with ending changed to –ide and add the word ion ion ion ion ion ion ion ion N3- nitride ion  Naming Binary Ionic Compounds Binary ionic compounds are named by naming the metal ion (cation) first, followed by the nonmetal ion (anion). KF K+, F‫־‬ potassium fluoride Al2S3 2Al3+, 3S2‫ ־‬aluminum sulfide CuCl2 Cu2+, 2Clˉ copper(II) chloride Fe2O3 2Fe3+, 3O2‫ ־‬iron(III) oxide  Names and Formulas of Binary Molecular Compounds The more cationlike (more metallic) element is written first (farther left and toward the bottom of the periodic table), followed by the more anionlike element. (Exception: NH3). H F  Naming Chemical Compounds N2F4 The prefix is added to the front of each to indicate the number of each atom. dinitrogen tetrafluoride  Naming Chemical Compounds Binary Molecular Compounds Whenever the prefix ends in “a” or “o” and the element name begins with “a” or “o” vowel, drop the “a” or “o” in the prefix. N2O4 dinitrogen tetroxide Whenever the prefix for the first element is “mono,” drop it. CO2 carbon dioxide CO carbon monoxide Give systematic names for the following compounds: (a) BrF3 Bromine trifluoride (b) P4O7 Tetraphosphorus heptoxide (c) S2Cl2 Disulfur dichloride  Naming Polyatomic Oxoanions Two oxoanions in a series: NO2 Nitrite ion; NO3 Nitrate ion SO32 Sulfite ion SO42 Sulfate ion fewer oxygens more oxygens -ite ending -ate ending  Naming Polyatomic Oxoanions Polyatomic anions containing oxygen with more than two members in the series. When there are more than two oxoanions in a series, the prefix hypo- (meaning “less than”) is used for the ion with the fewest oxygens, and the prefix per- (meaning “more than”) is used for the ion with the most oxygens. per-….-ate perchlorate ClO4- -ate chlorate ClO3- -ite chlorite ClO2- hypo-….-ite hypochlorite ClO-  Naming Polyatomic Ions Polyatomic anions containing oxygen with additional hydrogens are named by adding hydrogen or bi- (one H), dihydrogen (two H), etc., to the name as follows: CO32- carbonate ion HCO3- hydrogen carbonate ion/ bicarbonate ion PO43- phosphate ion HPO42- hydrogen phosphate ion H2PO4- dihydrogen phosphate anion Naming Compounds with Polyatomic Ions Name of cation with name of anion CaCO3 Ca2+, CO32- calcium carbonate FeSO4 Fe2+, SO4 2‫ ־‬iron(II) sulfate NaH2PO4 Na+, H2PO4‫ ־‬sodium dihydrogen phosphate Fe(ClO4)3 Fe3+, 3 ClO4‫ ־‬iron(III) perchlorate Names and Formulas of Acids  Names and Formulas of Acids The names of acids are related to the names of anions. Naming Binary Acids Emphasize the fact that a molecule is an acid by altering the name. HCl(g) hydrogen chloride HCl(aq) hydrochloric acid HF(g) hydrogen fluoride HF(aq) hydrofluoric acid - ide becomes hydro-…-ic acid  Naming Oxoacids Anion “-ate” suffix becomes an “-ic” suffix in the acid. Anion “-ite” suffix becomes an “-ous” suffix in the acid. HNO3 (aq) H+ (aq) + NO3- (aq) Nitric acid Nitrate ion HNO2 (aq) H+ (aq) + NO2- (aq) Nitrous acid Nitrite ion The oxoanion prefixes “hypo-” and “per-” are retained. BrO4‫־‬ perbromate ion HBrO4 perbromic acid BrO3‫־‬ bromate ion HBrO3 bromic acid BrO2‫־‬ bromite ion HBrO2 bromous acid BrO‫־‬ hypobromite ion HBrO hypobromous acid Write formulas for the nine compounds that can form between the following ions: NH4+ Ca2+ Fe3+ NO3- SO42- PO43- Name each of the compounds. NH4NO3 Ammonium nitrate Ca(NO3)2 Calcium nitrate (NH4)2SO4 Ammonium sulfate CaSO4 Calcium sulfate (NH4)3PO4 Ammonium phosphate Ca3(PO4)2 Calcium phosphate Fe(NO3)3 Iron(III) nitrate Fe2(SO4)3 Iron(III) sulfate FePO4 Iron(III) phosphate Name each of the following compounds. What are the charges on the positive ions in these compounds? +3 Al2(SO4)3 Aluminum sulfate +2 Mg(NO2)2 Magnesium nitrite +2 Ca(NO3)2 Calcium nitrate +1 CuClO3 Copper(I) chlorate +1 NaH2PO4 Sodium dihydrogen phosphate +1 KMnO4 Potassium permanganate Write formulas for the following species: Sulfite ion SO32- Perchloric acid HClO4 Bromite ion BrO2- Magnesium fluoride MgF2 Zinc carbonate ZnCO3 Potassium bromate KBrO3 Manganese(II) phosphate Mn3(PO4)2 Iron(III) oxide Fe2O3 Sulfur trioxide SO3 Cupper(I) hydroxide CuOH Sulfurous acid H2SO3 Thank you for your kind attention!