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2. Since sodium  has 1 valence electron it will lose 1 electron  to empty its  outer shell. This   will give the sodium  ion a positive  one charge (the ion will contain one more proton  than electrons).
 

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3. Since sulfur  has 6 valence electrons it will gain 2 electrons  to fill its outer shell with 8. This   will give the sulfur  ion a negative two charge (the ion will contain two more electrons than protons).

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4. Since potassium  has 1 valence electron it will lose 1 electron  to empty its  outer shell. This   will give the potassium ion a positive  one charge (the ion will contain one more proton  than electrons).

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5.  Since oxygen  has 6 valence electrons it will gain 2 electrons  to fill its outer shell with 8. This   will give the oxygen  ion a negative two charge (the ion will contain two more electrons than protons).
 
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6. Since iron  has 3 valence electron it will lose 3 electrons  to empty its  outer shell. This   will give the iron  a positive  three  charge (the ion will contain three  more protons  than electrons).

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7. Since phosphorus  has an atomic number of 15 it contains 15 protons. Atoms are neutral therefore there are 15 electrons in the phosphorus atom. Phosphorus has an atomic mass of 32 which means that the nucleus must contain 17 neutrons and 15 protons. The fifteen electrons are arranged in the following manner: two in the first shell, eight in the second shell, and five in the third shell.

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8. The correct  answer is "b". Remember ions have a charge, postive if they lose electrons and negative if they gain electrons.

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9. The correct  answer is "a". Remember atoms are neutral.

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10. The correct answer is "c". Molecules are usually two or more atoms bonded together.
      Examples CO = carbon monoxide,  HCl = hydrochloric acid,  H₂0 = water.

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11. The correct answer is    K₂  O -------->  2 K+     +     O=
 
                                         reactants             products

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12. Calcium hydroxide would be a base because is disassociates into hydroxide ions which can combine with hydrogen ions in water thus the solution will have more hydroxide ions than hydrogen ions and the solution would be basic.

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13. Magnesium chloride would be a salt because there is neither acid ions (H+) nor hydroxide ions (OH-) when it disassociates in water.

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14. Sulfuric acid  will form hydrogen ions (H+) when it disassociates in water thus forming an acid.

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15.  The molecular weight of carbon dioxide  is 44 amu. The sum of the single carbon atom and two oxygen atoms in carbon dioxide is 44 amu.

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16.  The molecular weight of sulfuric acid is  98 amu. The sum of two hydrogen, single sulfur and four  oxygen atoms in sulfuric acid is 98 amu.
 
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17.

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