Chapter 7 Chemical Formulas

Chemical Formulas and Names  ___________: Indicate the _________ of each atom in a formula  ______________: molecular compounds composed of only _______ and ________.  Ex. Al 2 (SO 4 ) 3 *subscript 2 refers to ________ *subscript 4 refers to __________ in the sulfate ion *subscript 3 refers to everything inside the _____, giving us 3 _________, with a total of 3 _______ atoms and 12 __________ atoms. 7-2

Chemical Formulas and Names  _____________: ions formed from a _________ atom  Monatomic ________ (+) are named after the element. Ex. Sodium = sodium  Monatomic _______ ( -), the end of the element name is dropped and _____ is added.  Ex. Chlorine = chloride oxygen = oxide 7-3

Balancing Charges  ______________: compounds composed of __________  The total ________ and ________ charges must be _______  Charges are _________ by having ___________ of an ion, which is indicated by a __________  Ex. ________________ = Mg +2 and Br - ~ _____________ are not balanced, you need ________of the bromines to balance the charge: MgBr 2 7-4

Balancing Charges Ex. What is the formula for __________________? 1. To write _________ ionic formulas, first write the ________ for the ions side by side, _________ first: Al 3+ O ___________________ by using the absolute value of each ion’s ________ as the _______ for the other ion: Al 2 3+ O Check the subscripts and ___________ ____________. Final answer = Al 2 O 3 7-5

Practice 1) Write balanced formulas for the following binary ionic compounds: a) Sodium chloride:________________________ b) Zinc Oxide:____________________________ c) Aluminum Bromide:_____________________ a) Barium Phosphide:______________________ 7-6

Practice 1) Write balanced formulas for the following binary ionic compounds: a) Sodium chloride:________________________ b) Zinc Oxide:________________________ c) Aluminum Bromide:________________ d) Barium Phosphide:_________________ 7-7

Naming Binary Compounds  _______________: naming system for chemicals  For ____________ ionic compounds, name the ______ first, then the _______.  Ex. ________ is calcium chloride. 7-8

Practice 2) What are the names of the following binary ionic compounds? a) Sr 3 N 2 :___________________ b) KI:______________________ c) Li 2 S:____________________ 7-9

Practice 2) What are the names of the following binary ionic compounds? a) Sr 3 N 2 : b) KI: c) Li 2 S: 7-10

Naming Binary Compounds  Some ________ form cations with _____________, a _____________ is used in the name to indicate the _________ of the ion. ex. Iron __ = Fe +2 Iron __ = Fe +3 ex. What is the formula for copper II oxide? Cu +2 O -2 = Cu 2 O 2 = ____ 7-11

Practice 3) What are the formulas for the following binary ionic compounds? a) Iron III sulfide:____________ b) Copper I oxide:____________ 4) What are the names of the following binary ionic compounds? a) CrF 2 :_____________________ b) Pb 3 N 4 :____________________ 7-12

Practice 3) What are the formulas for the following binary ionic compounds? a) Iron III sulfide:______________ b) Copper I oxide:______________ 4) What are the names of the following binary ionic compounds? a) CrF 2 :_____________________ b) Pb 3 N 4 :____________________ 7-13

Polyatomic Ions  ______________: are made up of more that one atom.  _____________: polyatomic ions that contain oxygen. (the name of the ion with the _________ number of O atoms ends in ______, with _______ O atoms is _____) ex. NO 2 - = nitrite NO 3 - = nitrate 7-14

Writing Polyatomic Formulas  Charges are _________ just like in binary compounds, but if you _______________ of a polyatomic ion, you must put it in __________ with your __________ on the __________. ex. What is the formula for tin IV sulfate? Sn 4+ SO 4 2- = Sn(SO 4 )

Practice 5) Write the formulas for the following ionic compounds: a) Sodium iodide:_____________ b) Lithium nitrate:_____________ c) Copper II sulfate:___________ d) Sodium Carbonate:__________ e) Potassium perchlorate:_______ 7-16

Practice 5) Write the formulas for the following ionic compounds: a) Sodium iodide:______________ b) Lithium nitrate:______________ c) Copper II sulfate:_____________ d) Sodium Carbonate:____________ e) Potassium perchlorate:__________ 7-17

Practice 6)Write the names for the following ionic compounds: a) Ca(OH) 2 ____________________ b) KClO 3 :______________________ c) NH 4 OH:_____________________ d) Fe 2 (CrO 4 ) 3 :___________________ e) KClO:_______________________ 7-18

Practice 6)Write the names for the following ionic compounds: a) Ca(OH) 2 :_____________________ b) KClO 3 :_______________________ c) NH 4 OH:______________________ d) Fe 2 (CrO 4 ) 3 :___________________ e) KClO:_______________________ 7-19

Naming Binary Molecular Compounds  ________________________:  ____________ bonded binary molecules are named using _________ to designate the number of atoms in the molecule. The only __________ is that if the first atom in the molecule has only one atom, the ____________ is dropped (understood)  ex. CO is carbon ___________ CO 2 is carbon ___________ 7-20

Practice 7) Name to following binary molecular compounds using the prefix system: a) H 2 0:_____________________________ b) N 2 O 3 :____________________________ c) P 4 O 10 :___________________________ 8) Write the formula for the following binary molecular compounds: a) Sulfur dioxide:__________________________ b) Phosphorous pentabromide:________________ c) Carbon tetrachloride:_____________________ 7-21

Practice 7) Name to following binary molecular compounds using the prefix system: a) H 2 0:________________________________ b) N 2 O 3 :_______________________________ c) P 4 O 10 :_______________________________ 8) Write the formula for the following binary molecular compounds: a) Sulfur dioxide:_________________________ b) Phosphorous pentabromide:_______________ c) Carbon tetrachloride:____________________ 7-22

Acids  ___________: consists of two elements, usually ____________ and one of the ____________.  _________: contain __________, oxygen and a ________ element.  _______: an ionic compound composed of a ______ and the anion from an _______. 7-23

Oxidation Numbers  _______________: a.k.a. oxidation states, indicates the _______________ of electrons among the ______________ in a molecular compound or a polyatomic ion. 7-24

Oxidation Numbers ~ Rules 1) Atoms of a pure element have an ox. # of zero 2) More electroneg. elements in binary molecular compounds have an ox. # equal to their charge as an anion, the less electroneg. elements have an ox. # equal to the cation. 3) Fluorine has an ox. # of -1. 4) Oxygen has an ox. # of -2 (exceptions are peroxides, -1, or when bonded Fluorine, +2) 5) Hydrogen has an ox. # of +1 when bonded with more electronegative elements, -1 when bonded with metals. 6) The algebraic sum of the ox. # in a neutral compound is zero. 7) The algebraic sum of the ox. # in a polyatomic ion is equal to the charge of the ion. 8) Ox. # can be assigned to atoms in ionic compounds. 9) A monatomic ion has an ox. # equal to the charge of the ion. 7-25

Oxidation Numbers ~ Examples  What are the oxidation numbers for the atoms in the following compounds:  H 2 O: O is -2, H is +1  HNO 3 : H is +1, O is -2 (x3 = -6), N must be +5  P 4 O 10 : O is -2 (x10 = -20), P must be +5 (x 4 = +20)  ClO 3 - : O is -2(x3 = -6), Cl must be

Naming Binary Compounds using Oxidation Numbers __________ binary molecular compounds using ______________ is called the _____________. Rather then using prefixes, you use a ____________ for the oxidation #.  H 2 O: Hydrogen __ oxide  P 4 O 10 : Phosphorus ___ oxide  NO: Nitrogen ___ oxide 7-27

Practice 9) What are the oxidation numbers for the atoms in the following compounds? a) PCl 3 :___________________________ b) CF 4 :_____________________________ c) PbO 2 :_____________________________ 10) Name the following compounds using the stock system: a) PCl 3 :___________________________ b) CF 4 :_____________________________ c) PbO 2 :______________________________ 7-28

Practice 9) What are the oxidation numbers for the atoms in the following compounds? a) PCl 3 :__________________________ b) CF 4 :__________________________ c) PbO 2 :_________________________ 10) Name the following compounds using the stock system: a) PCl 3 :__________________________ b) CF 4 :____________________________ c) PbO 2 :__________________________ 7-29

Using Chemical Formulas  _____________: the ______ of the atomic mass of all the atoms represented in the formula. (this is calculated just like ________, but the units are ______ instead of _______) Ex. What is the formula mass of water? H 2 O: H = _____ amu x 2 = ____ amu O = _____ amu x 1 = _____ amu Formula Mass of H 2 O = ______ amu 7-30

Practice 11) What is the formula mass of ammonia? _____: N = _____ amu x _ = _____ amu H = ___ amu x _ = ____ amu Formula Mass of ______ = _____ amu 7-31

Conversions Mass/Particles using molar mass: How many ___________ are in 29.36g of _______? 29.36g x 1 mol x x units 58.44g 1 mol NaCl = ___________ units 7-32

Conversions Mass/Particles using molar mass: What is the mass of _________ molecules ______? 5.39 x x 1 mol x g molecules6.022 x mol Molecules = _______ g water 7-33

Practice 12) How many atoms of hydrogen are in g of H 2 O? 13) What is the mass of 7.89 x formula units of BaCl 2 ? 7-34

Practice 12) How many atoms of hydrogen are in g of H 2 O? 13) 7-35

Percent Composition  _____________: the percentage by ______ of each element in a compound. % Comp. = total mass of element x 100 total mass of compound Ex. What is the % of H and O in one mole of H 2 O? _____ = 2 x 1.01 g H x 100 = _______ g H 2 O _____ = 1 x g O x 100 = _______ g H 2 O 7-36

Practice 14) What is the percent comp. of HClO 3 ? 7-37

Empirical Formulas  ______________: consists of the _________ for the elements combined in a compound, with subscripts showing the ____________________ of the different atoms in the compound. Ex. Empirical formula = H 2 O Molecular formula = H 4 O 2 = H 6 O

Empirical Formulas An unknown compound was found to be ________ and ______. What is the empirical formula? A ________________________________________: 75.0 g C x 1.0 mol C = ________ mol C atoms g C 25.0 g H x 1.0 mol H = _________ mol H atoms 1.01 g H Make a ______________ of each element __________ by the smallest number of moles. C: 6.25 = 1 H = 25.0 = 4 C:H is 1: the compound is CH

Empirical Formulas 15) Now you try one: determine the empirical formula for a compound containing 7.30 g Na, 5.08 g S and 7.62 g O. 7-40

Molecular Formulas ________________ give the actual number of atoms of each element in a molecular compound. This is always a ________________ of the empirical formula. By _________ the _________ by the _____________, you get the molecular formula. 7-41

Practice 16) Find the molecular formula for a compound that contains 4.90 g N and 11.2 g O with a molar mass of 92.0 g/mol. 7-42

Ch. 7 The End!