Experiment 11 Report Sheet Periodic Table and Periodic Law Date Lab Sec. Name De
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Experiment 11 Report Sheet Periodic Table and Periodic Law Date Lab Sec. Name Desk No A. Periodic Trends in Physical Properties (Dry Lab) Consult with your laboratory instructor as to the procedure and schedule for submitting your responses to the follow- ing questions about periodic trends. 1. Figure 11.1: Graphical data for the ionization energies of the elements show sawtooth trends across the periods of the elements. a. Locate the noble gas group of elements. What appears to be the periodic trend in ionization energies down the noble gas group (i.e., with increasing atomic number)? b. Scanning the graphical data for elements adjacent to and then further removed from the halogens, what general statement can summarize the trend in the ionization energies when moving down a group of elements? c. Which element has the highest ionization energy? d. What general statement can summarize the trend in the ionization energies when moving across a period of elements? 2. Figure 11.2: Graphical data for the atomic radii of the elements show generally decreasing trends across a period of elements. The noble gases are an anomaly a. Which group of elements has the largest atomic radii? b. Moving down a group of elements (increasing atomic number), what is the general trend for atomic radii? c. Which element has the largest atomic radius? d. What general statement can summarize the correlation of ionization energies to atomic radii for the elements? 3. Figure 11.3: Graphical data for the electron affinities of the elements show a number of irregularities, but a general increasing trend in values exists across a period of elements. a. Which group of elements has the highest electron affinities? b. Is the trend in electron affinities repetitive for Periods 2 and 3? Cite examples c. Which element has the highest electron affinity? d. Is there a correlation of electron affinities to atomic radii for the elements? If so, what is it? Cite examples. 4. Figure 11.4 shows repeated trends in density for the periods of elements. a. What is the general trend in densities for Periods 2 and 3? b. What is the trend in the densities moving down a group of elements? c. Which section of the periodic table (see Introduction) has elements with greater densities? d. Which element has the greatest density?Explanation / Answer
1
a) Ionization energy will decrease when we go down the nobel gas group (increase in atomic number). This is because if we go down the group, the electrons are filled in new energy level (shell). so the effective nuclear charge (The power of attracting the electron by the nuclear charge) (shielding) will decrease. so removel of electron from the outer shell is easy.
b) Normally when we move down the group, the ionization energy will decrease. this is because of the effective nuclear charge as already mention in the part (a)
c) Helium (He) has the largest first ionization energy.
d) The ionization energy increases from left to right in the periods. This is because when the atomic number increase, the new electrons are added in the same energy level (shell). so attraction between nucleas and electron is strong. so removal of electron is difficult.
2.
a) Group 1 (IA, Alkali Metals) Elements have the highest atomic radii. In this group an additional energy level (electron shell) is being added to each successive element.
b) Generally atomic radius increases as you go down the Group elements from top to bottom as an additional energy level (electron shell) is being added to each successive element.
c) Caesium has the largest atomic radius element. Caesium has a large valence shell and a relatively low effective nuclear charge which means that the electrons can move further away from the nucleus. Because of this, it is highly looking electropositive.
d) Ionization energy and atomic radii are inversely related to each other. So as atomic radius increases, ionization energy decreases. This s due to the increase of atomic radii will make the electron less attracted by the nucleas. so removal is easy so ionization energy is less.
3.
a) Halogens series in Group 17 have a higher electron affinity.
b) Electron affinity increases across period 2 and 3 because the radius slightly decreses while the nuclear charge increases and so the ability to attract the electron also increase.
c) Chlorine has the highest electron affinity value. It has the electronic structure 1s2, 2s2, 2p6, 3s2, 3px2, 3py2, 3pz1 with 17 protons in the nucleus. But again the incoming electron feels a net attraction from the nucleus of 7+ (17 protons less the 10 screening electrons in the first and second levels).
d) If atomic radii increases electron affinity decreases. because when the atomic radii increases the effective nuclear charge will decrease in the outer shell. so the ability to attract the electron will decrease.
4.
a) Density is decreased when we move across period.
b) When we move down the group, the density will increase. As you go down the Group, the atomic radius increases, and so the volume of the atoms also increases. That means that you can't pack as many sodium atoms into a given volume as you can lithium atoms. But when you go down the Group, the mass of the atoms increases. That means that a particular number of sodium atoms will weigh more than the same number of lithium atoms.
c) Higher atomic nuber elements have higher density.
d) The highest density element is Osmium.
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