p.78

19. a. gaining electrons b. neither c. neither d. losing electrons e. losing electrons

20. a. H b. Na1+ c. CL1- d. Al3+

21. a. Kl: Potassium Iodide b. CaS:Calcium Sulfide c. FeBr3: Iron Bromide d. BaOH2:Barium Hydroxide e. NHHHH+ + POOOO3- f. Al203:Aluminum Oxide

22. The periodic table was created because Mendeleev wanted to illustrate periodic trends in the properties of then-known elements.

23.  A type of graph that clearly represents each number and how each could be used.

24. a. A data table is helpful before an investigation because it can set up the steps that need to be taken. b. Data tables are important during an investigation because it helps organize the investigation c. Data tables are important after an investigation because it is important to see what information was gathered.

25. a. They help organize each ion and ionic compound. b They do not show the # of neutrons.

26.  Calcium metal with chromium(111) because it is mire reactive.

27. B because they are more neutral

28. a. This is wrong because it would make a replacement reaction b.  Fe+Pb + 4 ---> Fe +3+Pb

Thanks!!!
Forever and Always,
Abi