Friday, July 1, 2011

Chemistry Assignment 1

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

Ans: Atoms are made up of 3 types of particles electrons , protons and neutrons . These particles have different properties. Electrons are tiny, very light particles that have a negative electrical charge (-). Protons are much larger and heavier than electrons and have the opposite charge, protons have a positive charge. Neutrons are large and heavy like protons, however neutrons have no electrical charge. Each atom is made up of a combination of these particles.

In all atoms, the number of protons and the number of electrons is always the same. The number of neutrons is very roughly the same as the number of protons, but sometimes it's rather more. The number of protons in an atom is called the atomic number and it tells you what type of atom you have. The total number of protons and neutrons added together is called the relative atomic mass.



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

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The sodium atom is drawn this way because it electronic configuration is (2.8.1).Sodium only has one valence electron, and it somehow needs to attain a full set of valence electrons. In order to do this, it can either gain 7 electrons or lose the one valence electron so that the level under it becomes the full set of valence electrons. Since it is too hard to gain 7 electrons during chemical bonding, it loses its valence electron.

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

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Sulfer atom is drawn this way because it electornic configuration is (2.8.6). And since it is easier to gain 2 more electrons than to lost 6 electrons to make the ion stable, hence the sulfer ions is drawn this way.


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

Ans: Isotopes means different atoms of the same element which have the same number of protons but different number of electrons. Chlorine-35 and Chlorine-37 have the same number of protons, but different number of neutrons. Chlorine-35 has 18 neutrons, while Chlorine-37 has 20 neutrons. Hence, Chlorine-35 atom and Chlorine-37 atoms are called isotopes.

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

Ans: Sulfur is a non-metal because on the periodic table it is in group (VI). And the non-metals usually fall on group (IV),(V),(VI) and (VII). While sodium is a metal because on the periodic table it fall on group (I). And most of the metal fall in group (I),(II) etc.

Sulfer is non-metal is also beacause it is an element incapable of forming simple positive ions in solution. Where most of the metal is positively charge.

Metals are non-brittle and malleable. And sodium is non-brittle and malleable, in conclusion it is a metal. Whereas, sulfer is brittle and non-malleable, hence it is a non-metal.

Non-metal form oxides that are acidic, and sulfer reacts with oxide to form sulfer dioxide, which is acidic (acid rain), thus it is a non-metal. Whereas, metals form oxides that are basic, and sodium reacts with oxide to form sodium oxides which is a basic oxide.