Unformatted text preview: 3 Chemical Compounds Introduction Water,ammonia,carbon monoxide,and carbon dioxideall familiar substancesare rather simple chemical compounds.The study of chemistry is mostly about chemical compounds,and in this chapter, we will consider a number of ideas about compounds.
Cane sugar C aspir in a vitamin C ar e chemical compounds How to deduce chemical formulas Some basic concepts In this chapter,we will learn How to use information incorporated into chemical formulas How to write chemical formulas 3-1 Types of Chemical Compounds and Their Formulas 3-2 The Mole Concept and Chemical Compounds 3-3 Composition of Chemical Compounds Content s 3-4 Oxidation States : A Useful Tool in Describing Chemical Compounds 3-5 Naming Compounds : Organic and Inorganic Compounds 3-6 Names and Formulas of Inorganic Compounds 3-7 Names and Formulas of Organic Compounds 3-1 Types of Chemical Compounds and Their Formulas Molecular Compounds
Chemical Compounds Ionic Compounds A molecular compounds is made up of discrete units called molecules,which typically consist of small number of nonmetal atoms held together by covalent bonds. To represent a molecular compound,we use a chemical formula,a symbolic representation that,at minimum,indicates the elements present the relative number of atoms of each element
The two elements present H2O Lack of subscript means one atom of O per formula unit Where no subscript is written,the number 1 is understood What about CCl4? Please talking about. Two H atoms per formula unit An empirical formula is the simplest formula for a compound;it shows the types of atoms present and their relative numbers.The subscripts in an empirical formula are reduced to their simplest whole-number ratio.
P2O5 is the empirical formula for P4O10 Acetic acid (C2H4O2),formaldehyde(CH2O), glucose(C6H12O6) all have the empirical formula CH2O. Generally, the empirical formula does not tell us a great deal about a compound. A molecular formula is based on an actual molecule of a compound. In some cases, empirical and molecular formulas are identical,such as CH2O formaldehyde. In other cases,the molecular formulas is a multiple of the empirical formula.
Empirical formula: CH2O Molecular formula:C2H4O2 Structural formula:
H H C H O C O H A structural formula shows the order in which atoms are bonded together in a molecule and by what types of bonds. T he va r i ous depi cti ons of mol ecul es di scussed a bove wi l l be used thr oughout thi s book.I n fa ct,vi sua l i za ti on of the si zes a nd sha pes of mol ecul a r si zes a nd sha pes i s one of the most i mpor ta nt a spects of moder n chemi str y. An ionic compound is made up of positive and negative ions joined together by electrostatic forces of attraction. The atoms of metallic elements tend to lose one or more electrons when they combine with nonmetal atoms,and the nonmetal atoms tend to gain one or more electrons.When electron transfer ,the metal atom becomes a positive ion(called a cation),and the nonmetal atom becomes a negative ion(called an anion). Na + Cl
Transfer one electron Na+ + Cl- Formula...
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- Spring '10
- Molecule, Ion