Tuesday, July 9, 2013

HW due Wednesday, July 10


13.
a. A horizontal row is known as a period, with elements listed in order of increasing atomic numbers.
b. A vertical column is known as  a group, with grouped elements that have similar properties.

14. Sodium (Na) and Rubidium (Rb).

15.
a. The noble gas family is located on the last row on the right side of the periodic table (the 8th column).
b. Noble gases are do not react.
c. Noble gases are chemically inert.

16.
a. MgF2
b. GaP

17. To determine the melting point of potassium (K),  we must average the melting points of  Na and Rb.

98 plus 39=137
137 divided by 2=68.5

18. The boiling point of iodine is higher than that of chlorine. If the atomic weight of an element is high, it's boiling point is also high; thus, because iodine's atomic weight is 127 and chlorine's atomic weight is 35, iodine must have a higher boiling point.

19.


20. 
a. Berylium= 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. An atom can only gain or loose electrons, so the protons always stay the same; thus, to create a lead atom with 2+, the atom had to loose two electrons, to become positive. 

22. 
a. 
Carbon: 12 
Calcium: 41
Platinum: 195
Uranium: 238 

b. Carbon contains two isotopes on the periodic table.

23. The mass number is not enough to justify the claim of the discovery of a new element; however, it would be very helpful to know what the atomic weight and the atomic number of the element.

24. An electron's mass is much much less than that of a proton or neutron (about 1/2000 the mass of the other two).

25. 

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