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

Ans: An atom is the smallest foundation unit or particle of an element. An atom is made up of three sub-atomic particles such as protons, neutrons and electrons. The nucleus of the atom is formed by the protons and neutrons and they are known as nucleons. Electrons move rapidly around the nucleus. All atoms are electrically neutral. It contains an equal number if positively charged protons and negatively charged electrons. The proton has a positive charge and it has a relative mass of 1 while the neutron has a no charge and it has a relative mass of 1. The electron has a negative charge and its mass is much lighter than that of a proton and neutron. The relative mass of an electron is 1/1840.





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

Ans:



A sodium atom has an electronic configuration of (2,8,1). In order to achieve stability, the atom need to lose one electron to achieve a full shell (2,8). Hence, the formula of sodium ion is Na+.



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



Sulfur ion:




A sulfur atom has an electronic configuration of (2,8,6). In order to achieve stability, the atom need to gain two electrons to achieve a full shell (2,8,8). Hence, the formula of sulfur ion is S 2-.





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

Ans: Isotopes are different atoms of the same element which have the same number of protons but different number of neutrons. Chlorine-35 and chlorine-37 have the same number of protons, which is 17 protons. Chlorine-35 has (35-17)=18 neutrons while chlorine-37 has (37-17)=20 neutrons. Since chlorine-35 and chlorine-37 belong to the same element, have different number of neutrons and same number of protons, they are called isotopes.

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

Ans: Sodium is a metal because it will lose 1 electron to complete the valance shell while Sulfur is a non-metal because it will gain 2 electrons to complete the valance shell. Metals lose electron(s) and become positively charged ion which is also known as a cation. Non-metals gain electron(s) and become negatively charged ion which is also known as an anion.