13. a. Row (horizontal): period
b. Column (vertical): group/family
14. Two elements other than lithium in the alkali metal family are sodium (Na) and potassium (K).
15. a. The noble gases are located on the far right side of the periodic table.
b. All noble gases are unreactive, which is a physical property that all noble gases share.
c. Noble gasses don't react chemically (chemically inert)
16. a. MgF2
b. GaP
17. The melting point for potassium is: 68.5'C
98 + 39 = 137
137/2 = 68.5
18. I would expect the boiling point of chlorine to be less than the boiling point of iodine because iodine has a greater atomic weight, therefore, it would need a higher boiling point then chlorine who has a lower atomic weight.
19. The table for each electrically neutral atom:
20. a. beryllium: 4 protons, 4 or 5 neutrons, 4 electrons
b. nitrogen: 7 protons, 7 or 8 neutrons, 7 electrons
c. neon: 10 protons, 10 or 11 neutrons, 10 electrons
21. I would correct this student's mistaken explanation by saying the lead atom must have gained two electrons to make the ion. It is incorrect to say the lead atom must have gained two protons because you cant loose or gain protons, but you can loose or gain electrons.
22. a. the mass number of each element:
Carbon: 6+6= 12
Carbon: 6+7= 13
Calcium: 20+21= 41
Platinum: 78+117= 195
Uranium: 92+ 146= 238
23. No, the elements mass number wouldn't be sufficient to justify the discovery of a new element because it doesn't supply enough information to determine the elements physical or chemical properties. It would be easier if the atomic weight or the atomic number was given because with that information you can determine the physical and chemical properties of the element, and even where it could be located.
24. The mass of an electron is about 1/2000 the mass of a proton or neutron. The electron weighs almost nothing compared to neutrons and protons.
25. Protons and neutrons needed for each magnesium isotope in this table:
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