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

Ans: An atom consists of 3 sub-atomic particles and 1 nucleus. The 3 sub-atomic particles are: Protons; Neutrons and Electrons. Protons and Neutrons are found in the nucleus whereas electrons are found in the electron shell. An electron is negatively charged while a proton is positively charged. In an element, the number of electrons is the same as the number of protons. Whereas in an ion, the number of electrons and protons differs. The nucleon number or relative atomic mass number ( usually located at the top left hand corner of the element box ) is the relative mass of all the protons, neutrons and electrons in the element.

Sub-atomic Particles	Relative Mass
Electron	1 / 1840
Proton	1
Neutron	1

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

Ans:

The sodium atom is drawn that way because its has 11 electrons and its electronic configuration is ( 2.8.1 ). Thus, it has 1 valence electron that determines its charge when it becomes an ion. The sodium ion is drawn in such a way because it has given away 1 valence electron in order to become stable during a reaction. Thus, its electronic configuration is now ( 2.8 ) and its charge is +1.

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

Ans:

The sulfur atom is drawn that way because its has 16 electrons and its electronic configuration is ( 2.8.6 ). Thus, it has 6 valence electron that determines its charge when it becomes an ion. The sulfide ion is drawn in such a way because it has gained 2 valence electron in order to become stable during a reaction. Thus, its electronic configuration is now ( 2.8.8 ) and its charge is -2.

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

Ans:

Chlorine Atoms	No. of Proton	No. of Electron	No. of Neutron
Chlorine-35	17	17	18
Chlorine-37	17	17	20

Isotopes are different atoms of the same element that have the same number of proton, electron but different number of neutron. Since Chlorine-35 and Chlorine-37 have the same number of proton, electron but different number of neutron, they are isotopes of chlorine. Thus, the average nucleon number of chlorine is [(75/100) x35 ] + [(25/100) x37]


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

Ans: Sulfur is a non-metal because it does not conduct electricity and it will gain 2 electrons to complete the valence shell to make it stable during a reaction. Sodium is a metal because it conducts electrocity and it will lose 1 electron to complete the valence shell to make it stable during a reaction