chemistry .

On Sunday, July 3, 2011 at 9:20 PM 0 comments ♥

1. What does an atom looks like? What are the sub-atomic particles inside it ? (talk about electrons, neutrons, protons, electron shells, nucleus.)

atom is the smallest foundation unit or particle of an element that can exist . it looks like a circle with shells outside , each shell contains electrons and they lose or gain electrons to stability . the sub-atomic particles are protons , neutrons and electrons . the proton is a positive charge (+1) , the electron is a negative charge (-1) , neutron is neutral , 0 . the mass of a proton is the same as the mass of the neutron . the mass of the electron is much lighter than a proton and neutron . proton's relative mass is 1 , electron's relative mass is 1/1840 , neutron's relative mass is 1 .

2. Draw the atomic structure of a sodium atom and a sodium ion. explain why you draw it this way.

sodium atom , ( 2.8.1 ) to gain stability , it needs to lose one electron on the outermost shell and causing it to become ( 2.8 ) , sodium ion .

3. Draw the atomic structure of a sulfur atom and a sulfide ion. explain why you draw it this way.

sulfur atom , (2.8.6) to gain stability , it needs to gain 2 electrons , to lose 6 electrons , too much effort are needed , to gain 2 electrons is easier than losing it . therefore , it becomes , (2.8.8)

4. Chlorine-35 atom and Chlorine-37 atom are called isotopes. Use these two examples to explain what is 'isotopes'.

isotopes are different atoms of the same element which have the same number of protons but different number of neutrons .
chlorines have the same number of protons ( 17 protons ) , cl-35 have 18 neutrons , cl-37 have 20 neutrons . therefore , they are isotopes .

5. Sodium is a metal and sulfur is a non-metal. why we classify them this way?

sodium is na+ , positive charged , and it's in period I , therefore it is a metal .
sulfur is S2- , negatively charged , and it's in period VI , therefore it is a non metal .