Periodic Data and Trends

Graphing Periodic Trends The Periodic Table is arranged according to Periodic Law. The Periodic Law states that when elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern. These patterns can be discovered by examining the changes in properties of elements on the Periodic Table. The properties that will be examined in this lesson are: atomic size, electronegativity, and ionization energy. Procedure 1. Use excel (office 365) or a similar program to create 3 graphs (scatterplot – straight link connections between data points). Give the graph an appropriate title and label the axes (the x-axis is ‘atomic number’ for all graphs). 2. Cut and paste the graphs onto a word document so that their x-axes are in line. 3. Label/high-light the data points with the symbol of each alkali metal, halogen and noble gas. 4. Use your graphs to complete the analysis questions (type your response in a different colour!). below. Post your completed assignment to your edublog (2 students may post identical assignments) using the tag: mstilsnerchem11coop QUESTIONS: use the periodic table below to summarize the following trends. 1. Based on your graphs, what is the trend in atomic radius across a period? Down a family? The atomic radius gets smaller and smaller near the end of the period, then suddenly increases in the next period or row. The metals in each family are in positions relative to each other; the alkali metals are the ones with the largest radius in their period, and the noble gases have the smallest. 2. Based on your graphs, what is the trend in ionization energy across a period? Down a family? The ionization energy of each atom in one period grows as their radius size decreases. The first period has the most ionization energy in total, compared to the other periods. In this graph, the positions of atoms in each family are also similar; except this time the halogens are the ones with the most energy and noble gases the least. 3. Based on your graphs, what is the trend in electronegativity across a period? Down a family? Looking opposite to the first graph, the electronegativity increases as the radius decreases in size, but at the start of the next period, the electronegativity suddenly drops. Comparing the families, alkali metals have the least electronegativity and the noble gases have the most. The lesser number of electrons atoms need to fill their outer shell, the higher the electronegativity. 4a) What is happening to the number of protons and the number of energy levels as you move across the periodic table from left to right? How and why does this affect atomic radius. The number of protons is increasing but the energy level remains the same. As more and more protons are added, the ionization energy increases, having a stronger pull on the valence electrons. This will also increase the attractive force to the nucleus of the atom, making the atom’s radius smaller. Since the energy levels aren’t changing, new shells or electrons won’t be added, allowing the radius to decrease as you move across the periodic table. b) What happens to the number of energy levels as you move down a column on the periodic table. How and why does this effect ionization energy? The number of energy levels increases by 1 as you move down. This makes the elements have less ionization energy the further you go down, because they have more shells. Having more shells will make the radius of the atom larger, and the attractive force won’t be as strong anymore. That means that it’ll be easier to remove the outer electrons, making the element have a smaller ionization energy. c) What happens to the effective nuclear charge as you move across a period on the periodic table? How does this effect ionization energy and electronegativity? The effective nuclear charge increases, causing both the ionization energy and electronegativity to increase. 5a) Which group contains elements which are easiest to ionize? Explain why this is the case. The alkali metals. They have the least ionization energy and the largest radius, since they only brave one valence electron. This makes it easy for other elements to take that one electron. b) Explain why the third ionization energy of Ca would be much higher than the 1st and 2nd ionization energy Ca The amount of energy required to remove the electrons in the first energy level would be higher, since they’re closest to the protons. That makes the attractive force much stronger, so removing the electrons in the second or third energy level would be easier. 6. Which element would have the highest electronegativity in each set below? Explain why this is. a) Ca, Be or Mg b) B, Li, or F A) Beryllium B) Fluorine Beryllium needs 6 more electrons to fill it’s last shell. Magnesium needs 16, and calcium needs 30. It requires less electrons to become stable, causing it to be more electromagnetic. Fluoride is the most electromagnetic element, since it needs only 1 more electron and is in the second energy level. 7. Write (or type) the electron configuration of each atom (high-light the valence electrons) and it’s corresponding ion below each sketch (atomic radii are given in angstroms (1 x 10-10 M). N: [He] 2s2, 2p3 N3-: [He] 2s2, 2p6 Na: [Ne] 3s1 Na+: [He] 2s2, 2p6 O: [He] 2s2, 2p4 O2-: [He] 2s2, 2p6 Mg: [Ne] 3s2 Mg2+: [He] 2s2, 2p6 F: [He] 2s2, 2p5 F-: [He] 2s2, 2p6 Al: [Ne] 3s2, 3p1 Al3+: [He] 2s2, 2p6 9. Over the blank periodic table provided, write or type the number of valence electrons and the expected ion charge for the transition metal block and for the families to the left and right of the transitions metals (the alkali metals have been done as an example). Note: Carbon and boron do not normally form ions and are thus blanked-out