Answer Key to the First Review

Basics
1. An element contains just one type of an atom.
2. A compound is two or more different atoms bonded together to make neutral particle.
3. A chemical change will make a new substance (ex. burning), a physical change does not (ex. melting, boiling).

4. Review your sig figs and how to use them in calculations.
   
5. a) D = m/V = 35.94 g/ 3.18 mL = 11.3 g/mL
   b) V = m/D = 72.98 g/ 2.70 g/mL = 27.0 mL

6. a)

   b)

   The Atom

7. Look in your book.
8. proton - p⁺, 1 amu, in the nucleus; electron - e^-, 1/1840 amu, outside the nucleus; neutron - n^o, 1 amu, in the nucleus.
9. Rutherford's gold foil experiment. Look in the book for the rest.
10. An isotope is an atom of an element that has a different number of neutrons.
11. Cathode Ray Tube experiment. Look in your book.
12. Fill in the following table. (It includes ions, which are in a later chapter, but might as well cover it now.)

    Element or Ion Name	Element or Ion Symbol	Atomic Number	Atomic Mass	# of p+	# of e-	# of no	charge
    calcium ion	Ca+2	20	40	20	18	20	+2
    carbon	C	6	13	6	6	7	0
    sulfide ion	S-2	16	32	16	18	16	-2
    tin	Sn	50	119	50	50	69	0
    iron (III) ion	Fe+3	26	56	26	23	30	+3

13. 

    Atomic Spectra

14. Thomson - "plum pudding" model, a positive blob with electrons stuck in it. Rutherford - protons in the nucleus, electrons outside of the nucleus. Bohr - nucleus contains protons and neutrons, electrons in definite orbits, or energy levels, outside the nucleus. Quantum Mechanical Model - nucleus with protons and neutrons, electrons in probability regions outside the nucleus.
15. s - 1 orbital, 2 e^- total; p - 3 orbitals, 6 e^- total; d - 5 orbitals, 10 e^- total; f - 7 orbitals, 14 e^- total.
16. Look in your book.
17. a) 1s²2s²2p⁶3s¹   b) 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶   c) 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²4f¹⁴5d³
18. VIBGYOR (opposite of ROYGBIV) Remember that red is at 700 nm and violet at 400 nm.
19. 

    

20. This is best explained by looking at the second part of the atomic spectra page.

    Formulas

21. a) metal   b) nonmetal   c) metal   d) metalloid   e) nonmetal
22. Calcium forms a +2 ion when it loses two electrons to become like argon. It is now called the calcium ion.
23. Phosphorus forms a -3 ion by gaining 3 electrons to become like argon. It is now called the phosphide ion.
24. A molecular compound is composed of two nonmetals. An ionic compound is formed from oppositely charged particles being attracted, usually a metal and a nonmetal.
25. KNOW YOUR POLYATOMIC IONS!
26. a) CaI₂ ionic   b) PCl ₅ molecular   c) (NH₄)₂S ionic   d) Cu₂HPO₃ ionic  
    e) N₂O₅ molecular   f) Sn(C₂O₄)₂ ionic
27. a) potassium permanganate   b) tin (II) dichromate   c) disulfur trioxide   d) sodium nitrate  
    e) lead (IV) hydrogen carbonate

    Mole Conversions

28. 
29. The number of grams in one mole is the same as the formula mass.
    Ca(HCO₃)₂: (1 Ca x 40.08) + (2 H x 1.01) + (2 C x 12.01) + (6 O x 16.00) = 162.12 g/mole
30. 

31. 

32. 

33. 

34. 

35. 

36. a)
    b)the formula mass of C₅H₁₀O₂ = 102 g/mol. The molecular mass = 204 g/mol.
    204/102=2. Multiply all by 2 to get C₁₀H₂₀O₄

    Chemical Reactions

37. The five types of reactions are: single replacement, double replacement, combination, decomposition, and combustion. Look in your book or notes for further descriptions.
38. An equation must be balanced to conserve mass (matter).
39. a) 2 C   +   O₂ --> 2 CO   combination
    b) 2 KClO₃ --> 2 KCl   +   3 O₂   decomposition
    c) 2 FeCl₃   +   3 Ca(OH)₂ --> 2 Fe(OH)₃   +   3 CaCl₂   double replacement
    d) Mg   +   2 AgNO₃ --> 2 Ag   +   Mg(NO₃)₂   single replacement
    e) 2 C₄H₁₀   +   13 O₂ --> 8 CO₂   +   10 H₂O   combustion
    f) 4 K   +   O₂ --> 2 K₂O   combination
40. Write a balanced net ionic equation for each reaction.
    a) Pb(NO₃)_{2 (aq)}   +   2 NaCl_(aq) --> PbCl_{2 (s)}   +   2 NaNO_{3 (aq)}
    net ionic = Pb⁺²_(aq)   +   2 Cl^-1_(aq) --> PbCl_{2 (s)}

    b) Zn_(s)   +   2 HCl_(aq) --> ZnCl_{2 (aq)}   +   H_{2 (g)}
    net ionic = Zn_(s)   +   2 H⁺¹_(aq) --> Zn⁺²_(aq)   +  H_{2 (g)}