1. Chapter 4 Chemical Foundations: Elements, Atoms, and Ions

2. Chapter 4 Table of Contents Return to TOC Copyright © Cengage Learning. All rights reserved 2 4.1 The Elements (see Part 1) 4.2 Symbols for the Elements (see Part 1) 4.3 Dalton’s Atomic Theory (see Part 1) 4.4 Formulas of Compounds (see Part 1) 4.5 The Structure of the Atom (see Part 1) 4.6Introduction to the Modern Concept of Atomic Structure (see Part 1) 4.7Isotopes (see Part 1) 4.8Introduction to the Periodic Table (see Part 1) 4.9Natural States of the Elements 4.10Ions 4.11Compounds That Contain Ions

3. Section 4.9 Natural States of the Elements Return to TOC Copyright © Cengage Learning. All rights reserved 3 Most elements are very reactive. Elements are not generally found in uncombined form.  Exceptions are: Noble metals – gold, platinum and silver Noble gases – Group 8

4. Section 4.9 Natural States of the Elements Return to TOC Copyright © Cengage Learning. All rights reserved 4 Diatomic Molecules Nitrogen gas contains N 2 molecules. Oxygen gas contains O 2 molecules.

5. Section 4.9 Natural States of the Elements Return to TOC Copyright © Cengage Learning. All rights reserved 5 Diatomic Molecules

6. Section 4.9 Natural States of the Elements Return to TOC Copyright © Cengage Learning. All rights reserved 6 Different forms of a given element. Example:  Solid carbon occurs in three forms. Diamond Graphite Buckminsterfullerene Allotropes

7. Section 4.9 Natural States of the Elements Return to TOC Copyright © Cengage Learning. All rights reserved 7 Carbon Allotropes

8. Section 4.10 Ions Return to TOC Copyright © Cengage Learning. All rights reserved 8 Atoms can form ions by gaining or losing electrons.  Metals tend to lose one or more electrons to form positive ions called cations.  Cations are generally named by using the name of the parent atom.

9. Section 4.10 Ions Return to TOC Copyright © Cengage Learning. All rights reserved 9 Nonmetals tend to gain one or more electrons to form negative ions called anions. Anions are named by using the root of the atom name followed by the suffix –ide.

10. Section 4.10 Ions Return to TOC Copyright © Cengage Learning. All rights reserved 10 Ion Charges and the Periodic Table The ion that a particular atom will form can be predicted from the periodic table. Group or FamilyCharge Alkali Metals (1A)1+ Alkaline Earth Metals (2A) 2+ Halogens (7A)1– Noble Gases (8A)0

11. Section 4.10 Ions Return to TOC Copyright © Cengage Learning. All rights reserved 11 Ion Charges and the Periodic Table

12. Section 4.10 Ions Return to TOC Copyright © Cengage Learning. All rights reserved 12 Exercise An ion with a 3+ charge contains 23 electrons. Which ion is it? a)Fe 3+ b)V 3+ c)Ca 3+ d)Sc 3+

13. Section 4.10 Ions Return to TOC Copyright © Cengage Learning. All rights reserved 13 Exercise A certain ion X + contains 54 electrons and 78 neutrons. What is the mass number of this ion? 133

14. Section 4.11 Compounds That Contain Ions Return to TOC Copyright © Cengage Learning. All rights reserved 14 Ions combine to form ionic compounds. Properties of ionic compounds  High melting points  Conduct electricity If melted If dissolved in water

15. Section 4.11 Compounds That Contain Ions Return to TOC Copyright © Cengage Learning. All rights reserved 15 Ionic compounds are electrically neutral. The charges on the anions and cations in the compound must sum to zero.

16. Section 4.11 Compounds That Contain Ions Return to TOC Copyright © Cengage Learning. All rights reserved 16 Write the cation element symbol followed by the anion element symbol. The number of cations and anions must be correct for their charges to sum to zero. Formulas for Ionic Compounds

17. Section 4.11 Compounds That Contain Ions Return to TOC Copyright © Cengage Learning. All rights reserved 17 Concept Check A compound contains an unknown ion X and has the formula XCl 2. Ion X contains 20 electrons. What is the identity of X? a)Ti 2+ b)Sc + c)Ca 2+ d)Cr 2+

18. Section 4.11 Compounds That Contain Ions Return to TOC Copyright © Cengage Learning. All rights reserved 18 Concept Check A member of the alkaline earth metal family whose most stable ion contains 36 electrons forms a compound with bromine. What is the correct formula for this compound? a)CaBr 2 b)KrBr c)RbBr d)SrBr 2