Metal A substance or mixture that has a characteristic luster or shine and is generally a good conductor of heat and electricity Nonmetal An element that does not exhibit the characteristics of a metal Metalloid An element having characteristics of both metals and nonmetals
Chemical Compounds and Bonds Chemical Bonds - The electrostatic forces that hold the atoms of elements together in the compound. Covalent Compounds - Electrons are shared between atoms of different elements to form Covalent Cpds. Ionic Compounds - Electrons are transferred from one atom to another to form Ionic Cpds. “Cations” - Metal atoms lose electrons to form “ + ” ions. “Anions” - Nonmetal atoms gain electrons to form “ - ” ions. Mono-atomic ions form binary ionic compounds
Figure 2.16: Molecular and structural formulas and molecular models.
Chemical Formula A notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in the substance
Molecule A definite group of atoms that are chemically bonded together (tightly connected by attractive forces) Molecular Formula A formula giving the exact number of different atoms of an element in a molecule
An ion is an electrically charged particle obtained from an atom or chemically bonded group of atoms by adding or removing one or more electrons. • A cation is a positively charged ion formed by losing one or more electrons. • An anion is a negatively charged ion formed by gaining one or more electrons.
An ionic compound is composed of cations and anions. • Ions are arranged in a repeating three-dimensional pattern, forming a crystal. • The formula of an ionic compound gives the smallest possible integer number of ions in the substance (without writing charges) so that the combination is electrically neutral. • The formula gives the formula unit of the compounds. A formula unit is not a molecule!
What is formula of the ionic compound of Mg2+ and N3-? • The common multiple of the charges is 6, so we need three Mg2+ and two N3-. The resulting formula is • Mg3N2
What is the formula of the ionic compound of Ca2+ and PO43-? • The common multiple of the charges is 6, so we need three Ca2+ and two PO43-. The resulting formula is • Ca3(PO4)2
Organic Compounds • An important class of molecular substances; they contain carbon combined with other elements – notably hydrogen, oxygen, and nitrogen. • Hydrocarbons contain only carbon and hydrogen.
Functional Group • Name of Group • Examples • Alcohol • Methyl alcohol • Ether • Dimethyl ether • Carboxylic acid • Acetic acid • A functional group is a reactive portion of a molecule that undergoes predictable reactions.
Chemical nomenclature is the systematic naming of chemical compounds. • Compounds that are not organic are called inorganic compounds. Carbon monoxide, carbon dioxide, carbonates, and cyanides are also classified as inorganic compounds.
Naming Inorganic Compounds • Name the cation. • Name the anion.
Monatomic ions • Ions formed from a single atom. • Common monatomic ions are listed on the next slide by group and by period.
Period • IA • IIA • IIIA • IVA • VA • VIA • VIIA • 1 • 2 • 3 • 4 • 5 • 6 Common Monatomic Ions of the Main-Group Elements • H- • Li+ • Be2+ • N3- • O2- • F- • Na+ • Mg2+ • Al3+ • S2- • Cl- • K+ • Ca2+ • Ga3+ • Se2- • Br- • Rb+ • Sr2+ • In3+ • Sn2+ • Te2- • I- • Cs+ • Ba2+ • Tl3+, Tl+ • Pb2+ • Bi3+
Rules for Predicting the Charge on a Monatomic Ion • 1. Most main-group metals have one monatomic ions with a charge equal to the group number. Al, in Group IIIA(3), has one ion, Al3+. Sr, in Group IIA(2), has one ion, Sr2+. K, in Group IA(1), has one ion, K+.
2. Some main-group metals with high atomic number have more than one cation. One cation will have the charge of the group number minus 2; the second cation will have a charge equal to the group number Pb in Group IVA(14) has two ions: Pb2+ and Pb4+ Tl in Group IIIA(13) has two ions: Tl+ and Tl3+
3. Most transition metals form more than one cation, of which one is +2. Zn and Cd form only the +2 ion. Ag forms only the +1 ion. • 4. Nonmetal main-group elements form one monatomic anion with a charge equal to the group number minus 8. F in Group VIIA(17) forms the F- ion. S in Group VIA(16) forms the S2- ion. N in Group VA(15) forms the N3- ion.
Naming Monatomic Ions • Monatomic cations are named after the element if the element forms only one cation.
If more than one cation forms: • In the Stock system, the charge is written using a Roman numeral and is enclosed in parentheses. Cu2+ is copper(II). Cu+ is copper(I). • In an older system, the suffic –ic (for the higher-charged cation) or –ous for the lower-charged cation) is added to the element’s stem. Cu2+ is cupric. Cu+ is cuprous.
Fe3+ is iron(III) or ferric ion. • Fe2+ is iron(II) or ferrous ion. • Hg2+ is mercury(II) or mercuric ion. • The second ion mercury forms is diatomic: • Hg22+ is mercury(I) or mercurous ion.
Cr3+ is chromium(III) or chromic ion. • Cr2+ is chromium(II) or chromous ion. • Mn2+ is manganese(II) or manganous ion. • Co2+ is cobalt(II) or cobaltous ion. • Zinc forms only Zn2+, so it is called zinc ion. • Cadmium forms only Cd2+, so it is called cadmium ion. • Silver forms only Ag+, so it is called silver ion.
Polyatomic Ion • An ion consisting of two or more atoms chemically bonded together and carrying an electrical charge. • Table 2.5 lists common polyatomic ions.
Cations • mercury(I) or mercurous Hg22+ • ammonium NH4+ • Anions • peroxide O2- • hydroxide OH- • cyanide CN-
phosphate PO43- • monohydrogen phosphate HPO42- • dihydrogen phosphate H2PO4- • carbonate CO32- • hydrogen carbonate (bicarbonate) HCO3- • sulfate SO42- • hydrogen sulfate (bisulfate) HSO4- • sulfite SO32- • hydrogen sulfite (bisulfite) HSO3-
acetate C2H3O2- oxalate C2O42- chromate CrO42- dichromate Cr2O72- permanganate MnO4- nitrate NO3- nitrite NO2-
hypochlorite ClO- chlorite ClO2- chlorate ClO3- perchlorate ClO4-
What are the names of the following ionic compounds? • BaO • Cr2(SO4)3 BaO is barium oxide. Cr2(SO4)3 is chromium(III) sulfate or chromic sulfate.
What are the chemical formulas for the following ionic compounds? • potassium carbonate • manganese(II) sulfate The ions K+ and CO32- form K2CO3 The ions Mn2+ and SO42- form MnSO4
Binary Molecular Compounds • A compound composed of only two elements. • Binary compound of a metal and a nonmetal are generally named using ionic rules.
Naming Binary Molecular Compounds • We usually name the elements in the order given in the formula. • Name the first element using the element name. • Name the second element using the element root + -ide suffix.
Add a prefix to each name to indicate the number of atoms of that element. The prefix mono- is used only when needed to distinguish two compounds of the same two elements. • The final vowel of the prefix is often dropped when followed by an element name that begins with a vowel. Oxygen is the most common example. N2O4 dinitrogen tetroxide (“a” is dropped) NO nitrogen monoxide (only one “o”) (also called nitric oxide)
Prefixes (Greek) • One (1) mono- • Two (2) di- • Three (3) tri- • Four (4) tetra- • Five (5) penta- • Six (6) hexa- • Seven (7) hepta- • Eight (8) octa- • Nine (9) nona- • Ten (10) deca-
Some compounds have common names that differ from their systematic names: H2S hydrogen sulfide (the “di” is omitted) H2O water NH3 ammonia • Common names need to be memorized.
Acids and Corresponding Anions • Oxoacids contain hydrogen, oxygen, and a third central atom. To name an acid from its anion name: • Change an –ate suffix to –ic. • Change an –ite suffix to –ous. • Add the word “acid.”” • For example: HNO3 nitric acid H2SO4 sulfuric acid
Oxoanion • Oxoacid • CO32- • carbonateion • H2CO3 • carbonic acid • NO2- • nitrite ion • HNO2 • nitrous acid • NO3- • nitrate ion • HNO3 • nitric acid • PO43- • phosphate ion • H3PO4 • phosphoric acid • SO32- • sulfite ion • H2SO3 • sulfurous acid • SO42- • sulfate ion • H2SO4 • sulfuric acid
Oxo-anion • Oxo-acid • ClO- • Hypo-chlorite ion • HClO • hypochlorous acid • ClO2- • chlorite ion • HClO2 • chlorousacid • ClO3- • chlorateion • HClO3 • chloric acid • ClO4- • Per-chlorate ion • HClO4 • perchloricacid
What are the names of the following compounds? • OF2 • S4N4 • BCl3 OF2 is oxygen difluoride S4N4 is tetrasulfur tetranitride BCl3 is boron trichloride
What are the formulas for the following binary molecular compounds? • carbon disulfide • nitrogen tribromide • dinitrogen tetrafluoride The formula for carbon disulfide is CS2. The formula for nitrogen tribromide is NBr3. The formula for dinitrogen tetrafluoride is N2F4.
Bromine has an oxoacid, HBrO2, bromous acid (compare to HClO2, chlorous acid). What are the name and formula of the corresponding anion? The anion corresponding to HBrO2 isbromite, BrO2-.
Hydrate • A compound that contains water molecules weakly bound in the crystals. • The formula of a hydrate is written with a dot before the water molecule(s) included. • For example: CuSO45H2O
Hydrates are named using the anhydrous (without water) compound name followed by the prefix for the number of water molecules included and the word “hydrate.” • For example: CuSO45H2O is named copper(II) sulfate pentahydrate.
A compound whose common name is green vitriol has the chemical formula FeSO47H2O. What is the chemical name of this compound? FeSO47H2O is iron(II) sulfate heptahydrate.
Calcium chloride hexahydrate is used to melt snow on roads. What is the chemical formula of the compound? The chemical formula for calcium chloride hexahydrate is CaCl26H2O.
A chemical equation is the symbolic representation of a chemical reaction in terms of chemical formulas. • For example: 2Na + Cl2 2NaCl • Reactants are the starting materials; they are written on the left of the equation. • Products are the materials at the end of the reaction; they are written on the right of the equation.
Because a reaction must accurately describe the chemical reaction, it must be consistent with the law of conservation of mass. • When this is not the case, after correct formulas are written for each reactant and product, the coefficients are adjusted so that the same number of each atom is present in both the reactants and the products. • This is called balancingthe equation.
For example, the reaction of sodium with chlorine produced sodium chloride. • First, we determine the correct formula for each compound. Sodium is Na. Chlorine is Cl2. Sodium chloride is NaCl.
Second, we write the reaction. Na + Cl2 NaCl • Third, we check the number of each atom on each side of the equation. • This equation shows two Cl atoms on the reactant side and only one Cl atom on the product side. To balance the Cl atoms, we insert a coefficient of “2” before NaCl on the product side. Na + Cl2 2NaCl
Na + Cl2 2NaCl • Now the Na are not balanced: there is one on the reactant side and there are two on the product side. To balance Na, we insert the coefficient “2” before Na on the reactant side. 2Na + Cl2 2NaCl • The reaction is now balanced!