The Periodic Table and ion Formation

1. 4.1 The Periodic Table and ion Formation

5. 4.1 The Periodic Table and ion Formation • Valence Electrons: Electrons in the outer energy level • Periodic Trend: Elements have the same number of valence electrons as their group number (Group # = # of valence electrons) • Example: Elements in group 1 all have 1 valence electron • Valence electrons are involved in bonding between elements • knowing the number of valence electrons helps you predict the formation of compounds, name the compounds and write their chemical formulas

6. 4.1 The Periodic Table and ion Formation • Is there a link between charge and number of valence electrons ??

7. 4.1 Lewis Dot Diagrams • Lewis Dot Diagrams are an easy way of showing how many valence electrons an element has • Note that with Lewis diagrams, only valence electrons are shown and not the total number of electrons • To draw a Lewis dot diagram, simply draw the symbol for the element and then place dots around the symbol starting above the element and continuing in a clockwise fashion

8. 4.1 Lewis Dot Diagrams Activity: Draw Lewis dot diagrams for the first 20 elements

9. LEWIS DOT DIAGRAMS Lewis dot diagrams display valence electrons and help us visualize how atoms bond. [valence electrons: the electrons in the outer most orbit of the atom] Steps: - Element’s symbol as nucleus - Valence electrons are drawn as dots around the symbol Ex.

10. 4.1 The Periodic Table and ion Formation

12. 4.1 Ionic Solids • Ionic solids are made of a repeating pattern of ions • Ionic solids are held together by electrostatic forces of attraction in a solid known as a crystal lattice • Ionic compounds are soluble in water, conduct electricity and have high melting points

13. 4.1 Forming Ionic Compounds • Ionic Compounds are made of ions (charged particles formed when atoms gain or lose electrons) • Cation: A positively charged ion (atom loses electron) (Example: Na+1) • Anion: A negatively charged ion (atom gains electron) (Example: O2-) • When An ionic compound forms, one or more electrons from one atom are transferred to another atom

14. 4.1 Forming Ionic Compounds

15. 4.1 Forming Ionic Compounds

16. 4.1

17. 4.1 The Periodic Table and ion Formation • Ionic compounds are composed of a metal and one or more non-metals • Metals tend to lose electrons to form cations(see page 141) • Non-metals tend to gain electrons to form anions

18. IONS An atom or group of atoms with a chargeis called an ion Atoms can gain or lose electrons during chemical change Electrons are gained or lost to create a complete outer shell Ex. Oxygen Oxygen gains two electrons and becomes negative with a charge of 2-

19. Types of Ions cation: a positively charge ion anion: a negatively charge ion Metals generally become cations, non-metals generally become anions ionic compound: a compound make up of cation(s) and anion(s) The attraction between charges forms an ionic bond

20. Ionic Compounds ionic compound:a compound make up of cation(s) and anion(s) • The attraction between charges forms an ionic bond • Ionic compounds have crystal structures • Most ionic compounds dissolve in water by separating into their ions • Most ionic compounds are electrolytes

21. 4.1 Representing Ionic Compounds with Lewis Dot Diagrams [ [ [ [

22. 4.1 Representing Ionic Compounds with Lewis Dot Diagrams

23. 4.1 Representing Ionic Compounds with Lewis Dot Diagrams Li+ Li+ . 2- [Li]+ [Li]+ 2Li +

24. 4.1 Representing Ionic Compounds with Lewis Dot Diagrams • Now you try! Draw BR and Lewis Dot diagrams for: Li and S Mg and O Ca and F Al and F K and O Al and O Mg and N