1. Ions & Compounds

2. Ions atoms that have lost or gained electrons do this to get a stable outer shell (8) they now have a charge

3. Example 1 Lithium Atom Li 3 protons 3 electrons

4. Example 1 Lithium Atom Li 3 protons 3 electrons Lithium Ion Li + 3 protons 2 electrons

5. Example 2 Calcium Atom Ca 20 protons 20 electrons

6. Example 2 Calcium Atom Ca 20 protons 20 electrons Calcium Ion Ca 2+ 20 protons 18 electrons

7. As you can see from the two examples, metals tend to have 1, 2, or 3 valence electrons When they combine with other elements, they tend to lose these electrons

8. Example 3 Fluorine Atom F 9 protons 9 electrons

9. Example 3 Fluorine Atom F 9 protons 9 electrons Fluoride Ion F - 9 protons 10 electrons

10. Example 4 Sulfur Atom S 16 protons 16 electrons

11. Example 4 Sulfur Atom S 16 protons 16 electrons Sulfide Ion S 2- 16 protons 18 electrons

12. As you can see from the last two examples, nonmetals tend to have 5, 6, or 7 valence electrons

13. When they combine with other elements, they tend to gain electrons

14. As you can see from the last two examples, nonmetals tend to have 5, 6, or 7 valence electrons When they combine with other elements, they tend to gain electrons Naming nonmetal ions – ending changes to “ide”

15. Cations vs. Anions Cations are atoms that have lost an electron to become positively charged

16. Cations vs. Anions Cations are atoms that have lost an electron to become positively charged Calcium Ion = Ca 2+

17. Cations vs. Anions Anions are atoms that have gained an electron to become negatively charged

18. Cations vs. Anions Anions are atoms that have gained an electron to become negatively charged Fluoride Ion = F -

19. IONIC COMPOUNDS atoms combine with other atoms to form compounds and fill their outer shell this makes them stable one is now a cation and other an anion opposite charges so are ATTRACTED to each other (ionic bond) stay together stable compound

20. Properties of Ionic Compounds strong bond between + and – charged ions crystalline-shaped compound, so is hard and brittle high melting point (needs a lot of energy to break the bonds) conducts electricity when dissolved in water (doesn’t conduct in a solid state) Most are soluble in water (except CaCO 3 )

21. Writing Formulas for Ionic Compounds Zero Sum Rule: sum of the charges must equal zero total # of + charges + total # of - charges ex Mg + Cl 1.Write symbols, metal first MgCl 2.Write the charge above the symbol +2-1 MgCl

22. 3.Determine how many of each ion are needed to bring total charge to zero 1 (+2)+2 (-1)=0 MgCl 4.Write the chemical formula using the coefficients (red) as subscripts. Mg 1 Cl 2 5.Don’t write subscript 1 Mg Cl 2 Find the formula for aluminum and oxygen

23. Crisscross Method a shortcut method eg calcium and flourine 1.Write the symbols and their charges 2+1- CaCl 2. Crisscross the charges above so they now become coefficients Ca Cl 2 use the crisscross to find the formula for magnesium and oxygen

24. Naming Ionic Compounds the metal always goes 1st, non-metal 2 nd non-metal’s ending changes to ‘ide’ ex sodium + chlorine sodium chloride name the other ionic compounds you’ve written the formula for

25. Multiple Ionic Charges some metals can form more than one ion (multivalent) ex. iron can be Fe 2+ or Fe 3+

26. Naming Multivalent Compounds must include the ionic charge of the compound in the name comes after the metal, written in Roman Numerals (I, II, III, IV, V) ex. FeCl 2 Iron (II) Chloride whenever writing chemical name of a compound check to see if it has more than one charge

27. Polyatomic Ions stable gp of several atoms acting together as a single ion don’t break apart together have an overall charge ex. phosphate PO 4 3-