Chemistry

Topics: Atom, Oxygen, Chemical bond Pages: 5 (1281 words) Published: September 11, 2013
Unit 1 Key Questions Lesson 1

1. One argument against continuing research on the atom is that the cost continues to increase at an alarming rate, and the benefits seem to be declining. Whereas quantum chemistry experiments as early as 80 years ago were very cheap and yielded considerable practical results, now very few if any practical results are emerging, but the costs of experiments continues to increase. On the other hand a common argument for the continued research in atomic and subatomic structure is the desire for a greater understanding of the universe. As we study the interactions of very small particles, we can gain a better understanding of how they work together to ultimately create the world we live in. Also there is a practical goal of understanding subatomic particles. Current data on how atoms and electrons interact is based on observation alone, and the reasons are unknown. For this reason, the predictions are occasionally vastly inaccurate when involved in larger systems. For example, we cannot predict the energy states of an electron accurately once the number of electrons goes above 1, if insight can be shed into the design of the particles that because the behavior we observe, it will be the most significant practical discovery since the discovery of chemistry itself. 2. Visible light VIBGYOR has a frequency of about 760 micro meter and our human eye is sensitive to this spectra this is the reason why we can see visible light. All other spectra are not visible to our eye. Visible light which appears as white light is made of VIBGYOR colors, ultraviolet rays lay beside violet of visible light and has a lesser frequency than visible light. Ultraviolet light has lesser frequency with high power intensity than visible light; when we are exposed to UV rays it causes skin cancer and cataract in eye. Because of its power intensity it is widely used for anti microbial treatment for clothing, wood and other materials. Other applications include purification of water, detection of fake currency notes.

3.
a) 1S2,2S2,2P6,3S2,3P6,4S2,3D10,4P6,5S2,4D2

b) The electron configuration for Zr is [Kr] 4d2 5s2. Ions are formed by losing electrons in outer shells to obtain more stable electron configurations like those of noble gases. By losing 4 electrons, it would have the electron configuration of the noble gas, Kr. So that is why the Zr 4+ ion is formed.

c) The Zr ion is more stable than the Zr atom because an ion is formed by loosing valence electrons to attain a noble gas configuration. Elements gain or lose electrons to attain stability. The Zr atom loses four electrons to gain an inert gas configuration.

Unit 1 Key Question Lesson 2

4.

5.

6.
a)

b) The N atom in NH3 has sp^3 hybridization. Also of the 4 orbital’s on the atom Nitrogen there are 3 bonding pairs of electrons and one non bonding pair because it has one lone pair which is not involved in the bonding and the rest are all involved in the hybrid bonding. c) Nitrogen has a lone pair, therefore the lone pair pair-bond pair repulsion is greater than the bond pair-bond pair repulsion so the tetrahedral geometry of nitrogen will be distorted 7.

a)
i) CaBr2
2.9 -1 = 1.9
ii) Na3N
3-0.9 = 2.1
iii) CH4
2.5 – 2.2 = 0.3
b) CaBr2 is an ionic compound since its difference in electronegativity is greater than 1.7. Na3N is also ionic since its difference in electronegativity is greater than 1.7. CH4 is a molecular compound since its difference in EN is lower than 1.7. c) Going from most ionic to least ionic: Na3N, CaBr2, CH4. We find compounds containing metals on the left side of the tanking order because they are usually the most ionic.

Unit 1 Key Questions Lesson 3 8.
a)
b) It has the pyramidal shape.
c) It is not symmetrical,...
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