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Atoms, Ions and Molecules

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1 Atoms, Ions and Molecules
Formulas Nomenclature Acids Chemical equations

2 Metal Nonmetal Metalloid
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. Copyright © Cengage Learning. All rights reserved.

3 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. Copyright © Cengage Learning. All rights reserved.

4 Molecule Molecular Formula Empirical formula
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. Empirical formula A formula giving the simplest ratio of atoms in a compound (ionic or covalent) Copyright © Cengage Learning. All rights reserved.

5 Polymer A very large molecule that is made up of a number of smaller molecules repeatedly linked together. Monomers The small molecules that are linked together to form a polymer. Copyright © Cengage Learning. All rights reserved.

6 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. Copyright © Cengage Learning. All rights reserved.

7 A cation is named by its element name followed by the word ion.
A cation is a positively charged ion formed by losing one or more electrons. A cation is named by its element name followed by the word ion. For example, Na+ is the sodium ion, etc. Copyright © Cengage Learning. All rights reserved.

8 An anion is a negatively charged ion formed by gaining one or more electrons.
An anion is named by changing the last part of the element name to –ide followed by the word ion. For example, F- is the fluoride ion, O2- is the oxide ion, N3- is the nitride ion, etc. Copyright © Cengage Learning. All rights reserved.

9 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! Copyright © Cengage Learning. All rights reserved.

10 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 Copyright © Cengage Learning. All rights reserved.

11 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 Copyright © Cengage Learning. All rights reserved.

12 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. Copyright © Cengage Learning. All rights reserved.

13 A functional group is a reactive portion of a molecule that undergoes predictable reactions.
Copyright © Cengage Learning. All rights reserved.

14 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. Copyright © Cengage Learning. All rights reserved.

15 Naming Inorganic Compounds
The cation is always named first with the name of the cation without the word ion. The anion is named second with the name of the anion without the word ion. Examples: Cation Anion Name Na+ Br- Sodium bromide Mg2- O2- Magnesium oxide Al3+ Cl- Aluminum chloride Copyright © Cengage Learning. All rights reserved.

16 Monatomic ions Ions formed from a single atom.
Common monatomic ions are listed on the next slide by group and by period. Copyright © Cengage Learning. All rights reserved.

17 Copyright © Cengage Learning. All rights reserved.

18 Rules for Predicting the Charge on a Monatomic Ion
1. Most main-group metals have one monatomic ion 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+. Copyright © Cengage Learning. All rights reserved.

19 Pb in Group IVA(14) has two ions: Pb2+ and Pb4+
Some main-group metals with high atomic numbers have more than one cation. One cation will have the charge of the group number. The second cation will have a charge equal to the group number minus 2. Pb in Group IVA(14) has two ions: Pb2+ and Pb4+ Tl in Group IIIA(13) has two ions: Tl+ and Tl3+ Copyright © Cengage Learning. All rights reserved.

20 Zn and Cd form only the +2 ion. Ag forms only the +1 ion.
3. Most transition metals form more than one cation, one of which 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. Copyright © Cengage Learning. All rights reserved.

21 Naming Monatomic Ions Monatomic cations are named after the element if the element forms only one cation. Copyright © Cengage Learning. All rights reserved.

22 If a metal forms more than one cation:
In the Stock system, the charge is written using a Roman numeral enclosed in parentheses. Cu2+ is copper(II). Cu+ is copper(I). In an older system, the suffix –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. Copyright © Cengage Learning. All rights reserved.

23 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. Copyright © Cengage Learning. All rights reserved.

24 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+, called zinc ion. Cadmium forms only Cd2+, called cadmium ion. Silver forms only Ag+, called silver ion. Copyright © Cengage Learning. All rights reserved.

25 Polyatomic Ions An ion consisting of two or more atoms chemically bonded together and carrying an electrical charge. Table 2.6 lists common polyatomic ions. Copyright © Cengage Learning. All rights reserved.

26 Cations Anions mercury(I) or mercurous Hg22+ ammonium NH4+
peroxide O2- hydroxide OH- cyanide CN- Copyright © Cengage Learning. All rights reserved.

27 monohydrogen phosphate HPO42- dihydrogen phosphate H2PO4-
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- Copyright © Cengage Learning. All rights reserved.

28 acetate C2H3O2- oxalate C2O42- chromate CrO42- dichromate Cr2O72-
permanganate MnO4- nitrate NO3- nitrite NO2- Copyright © Cengage Learning. All rights reserved.

29 hypochlorite ClO- chlorite ClO2- chlorate ClO3- perchlorate ClO4-
Copyright © Cengage Learning. All rights reserved.

30 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. Copyright © Cengage Learning. All rights reserved.

31 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 Copyright © Cengage Learning. All rights reserved.

32 Binary Molecular Compounds
A compound composed of only two elements. Binary compound of a metal/hydrogen and a nonmetal are generally named using ionic rules. Copyright © Cengage Learning. All rights reserved.

33 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. Copyright © Cengage Learning. All rights reserved.

34 *Formula is written in order of increasing electronegativity
-for each element, use prefixes to indicate the number of atoms present -the less electronegative element assumes its common name -the more electronegative element has the –ide suffix added SO N2O H2S N2O PCl3 Sulfur dioxide Dinitrogen monoxide Hydrogen sulfide Dinitrogen pentoxide Phosphorus trichloride **1st element atom counting starts at 2 (di), 2nd element atom counting starts at 1 (mono)

35 Add a prefix to each name to indicate the number of atoms of that element. The prefix mono- is used for the first element only when needed to distinguish two compounds with 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)

36 Copyright © Cengage Learning. All rights reserved.

37 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.

38 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

39 Copyright © Cengage Learning. All rights reserved.

40 What are the names of the following compounds? OF2 S4N4 BCl3
OF2 is oxygen difluoride S4N4 is tetrasulfur tetranitride BCl3 is boron trichloride Copyright © Cengage Learning. All rights reserved.

41 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.

42 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 is bromite, BrO2-.

43 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: CuSO45H2O

44 copper(II) sulfate pentahydrate.
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: CuSO45H2O is named copper(II) sulfate pentahydrate. Copyright © Cengage Learning. All rights reserved.

45 A compound whose common name is green vitriol has the chemical formula FeSO47H2O. What is the chemical name of this compound? FeSO47H2O is iron(II) sulfate heptahydrate.

46 Calcium chloride hexahydrate is used to melt snow on roads
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 CaCl26H2O. Copyright © Cengage Learning. All rights reserved.

47 Chemical Equations *a chemical equation is a formal way of describing a chemical reaction using chemical formulas/symbols *Chemical reaction: the process by which matter is transformed into new substances *Components of a chemical equation: Reaction conditions Products reactants States of matter (chemical, physical)

48 First, we determine the correct formula for each compound.
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. Copyright © Cengage Learning. All rights reserved.

49 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 Copyright © Cengage Learning. All rights reserved.

50 The reaction is now balanced!
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! Copyright © Cengage Learning. All rights reserved.

51 Burning Charcoal: C (s) + O2 (g) CO2 (g) Reactant(s) States of mater
Product(s) States of mater

52 Components of a chemical reaction
*Reactants and products: -use correct formulas (and not empirical formulas) -elements are written as they occur naturally i.e. O2 instead of O * Multiple reactants or products are separated by ‘+’ sign *Reactants and products are separated by a continuous full arrow *Other types of arrows in chemistry: -half arrows, double headed arrows,etc

53

54 Natural forms of elements
Physical forms Gases: O, N, Cl, Grp 8A, F, H Liquids: Br, Hg Solids: All other elements Chemical forms Monoatomic: metals, noble gases etc Diatomic: Cl2, F2, O2, N2, Br2, I2 Polyatomic: S8, P4

55 Components of a chemical reaction
*States of matter -solid, (s) -Liquid, (l) -Gas, (g) -Aqueous, (aq) *Other conditions – normally shown above the arrow -heat -cooling -pressure -irradiation -catalyst

56 Balance the following equation: CS2 + O2  CO2 + SO2
Tally the number of each atom on each side: C 1 on reactant side; 1 on product side S 2 on reactant side; 1 on product side O 2 on reactant side; 4 on product side Begin by inserting the coefficient “2” before SO2 on the product side. We leave O2 until later because it is an element. Copyright © Cengage Learning. All rights reserved.

57 C 1 on reactant side; 1 on product side
CS2 + O2  CO2 + 2SO2 Tally the atoms again: C 1 on reactant side; 1 on product side S 2 on reactant side; 2 on product side O 2 on reactant side; 6 on product side Insert a “3” before O2: CS2 + 3O2  CO2 + 2SO2 Copyright © Cengage Learning. All rights reserved.

58 C 1 on reactant side; 1 on product side
CS2 + 3O2  CO2 + 2SO2 Tally the atoms again: C 1 on reactant side; 1 on product side S 2 on reactant side; 2 on product side O 6 on reactant side; 6 on product side The reaction is now balanced! Copyright © Cengage Learning. All rights reserved.

59 Balance the following equation: NH3 + O2  NO + H2O
Tally the number of each atom on each side: N 1 on reactant side; 1 on product side H 3 on reactant side; 2 on product side O 2 on reactant side; 2 on product side Begin by inserting the coefficient “2” before NH3 on the reactant side and the coefficient “3” before H2O on the product side. We leave O2 until later because it is an element. Copyright © Cengage Learning. All rights reserved.

60 N 2 on reactant side; 1 on product side
2NH3 + O2  NO + 3H2O Tally the atoms again: N 2 on reactant side; 1 on product side H 6 on reactant side; 6 on product side O 2 on reactant side; 4 on product side To balance N, insert a “2” before NO: 2NH3 + O2  2NO + 3H2O Copyright © Cengage Learning. All rights reserved.

61 N 2 on reactant side; 2 on product side
2NH3 + O2  2NO + 3H2O Tally the atoms again: N 2 on reactant side; 2 on product side H 6 on reactant side; 6 on product side O 2 on reactant side; 5 on product side Since this gives us an odd number oxygens, we double the coefficients on NH3, NO, and H2O and to balance O, insert a “5” before O2. Copyright © Cengage Learning. All rights reserved.

62 Tally the atoms again to double check: 4NH3 + 5O2  4NO + 6H2O
N 4 on reactant side; 4 on product side H 12 on reactant side; 12 on product side O 10 on reactant side; 10 on product side The reaction is now balanced! Copyright © Cengage Learning. All rights reserved.

63 Balance the following equation: C2H5OH + O2  CO2 + H2O
Tally the number of each atom on each side: C 2 on reactant side; 1 on product side H 6 on reactant side; 2 on product side O 3 on reactant side; 3 on product side Begin by balancing H. Insert the coefficient “3” before H2O on the product side. We leave O2 until later because it is an element. Copyright © Cengage Learning. All rights reserved.

64 Tally the number of each atom on each side:
C2H5OH + O2  CO2 + 3H2O Tally the number of each atom on each side: C 2 on reactant side; 1 on product side H 6 on reactant side; 6 on product side O 3 on reactant side; 5 on product side To balance C, insert a “2” before CO2. Copyright © Cengage Learning. All rights reserved.

65 Tally the number of each atom on each side:
C2H5OH + O2  2CO2 + 3H2O Tally the number of each atom on each side: C 2 on reactant side; 2 on product side H 6 on reactant side; 6 on product side O 3 on reactant side; 7 on product side To balance O, insert a “3” before O2. Copyright © Cengage Learning. All rights reserved.

66 Tally the number of each atom on each side:
C2H5OH + 3O2  2CO2 + 3H2O Tally the number of each atom on each side: C 2 on reactant side; 2 on product side H 6 on reactant side; 6 on product side O 7 on reactant side; 7 on product side The reaction is now balanced! Copyright © Cengage Learning. All rights reserved.

67 Write conventional chemical equations representing the following reactions:
Propane, C3H8 gas burns in air (oxygen) to form carbon dioxide and water Combustion of a diamond in excess oxygen produces carbon dioxide Aqueous solutions of sulfuric acid and sodium hydroxide react to give sodium sulfate and water Sulfur is burnt in air to form sulfur dioxide C3H8(g) O2(g) → 3CO2(g) H2O (l) C(s) O2(g) → CO2(g) H2SO4(aq) NaOH(aq) → Na2SO4(aq) H2O(l) S8(s) O2(g) → 8SO2(g)

68 Balance each of the following equations.
(a) Fe Cl2 −−→ FeCl3 (b) Fe O2 −−→ Fe2O3 (c) FeBr3 + H2SO4 −−→ Fe2(SO4)3 + HBr (d) C4H6O H2O −−→ C2H4O2 (e) C2H O2 −−→ CO H2O (f) C4H10O O2 −−→ CO H2O (g) C7H O2 −−→ CO2 + H2O (h) H2SiCl H2O −−→ H8Si4O HCl (i) HSiCl H2O −−→ H10Si10O HCl (j) C7H HNO3 −−→ C7H6(NO2) H2O C5H8O NaH HCl −−→ C5H12O NaCl


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