Relationships in the Periodic Table Lab Report Yashaswini Kanchi 03/26/24 Chem 004B - Section QR3 Professor Chabra
Introduction The purpose of this lab was to investigate how the properties of different elements relate to their respective positions in the Periodic Table. The purpose of the periodic table itself was made to allow chemists to concisely visualize the relationship between elements and their chemical and physical properties. The table specifically organizes the elements in a way that shows the common, recurring trends that can happen for a certain group or period. This repeating pattern of element properties refers to the periodicity of properties. Early on, chemists were able to observe elements "grouping", based on how certain elements would display similar properties, like lithium, sodium, and potassium. Originally, the elements in the table were organized by increasing atomic weight. However, Dmitri Mendeleev saw the gaps in the order, which prompted him to use his own knowledge of certain elements and other patterns to create a new format, to include what we know as transition metals. Mendeleev decided to use a format that focuses on columns and rows that grouped together the elements to create families. After much more knowledge was acquired, the elements in the periodic table are now able to be correctly organized by atomic number and not atomic weight. The modern restatement of Mendeleev's Periodic Law emphasizes how elements arranged in increasing atomic number show the true periodicity of chemical and physical properties. In this experiment, many different groups and trends were explored. Part I of the experiment explores the behavior and reactivity of group I, II, and III metals by observing reactions of different elements in water and HCl. Part II of the experiment focuses on the properties of halogens, which are part of group VIIA, and how molecular weight affects physical states. Finally, part III of the experiment uses litmus papers to help compare the relative acidic or basic properties of hydroxides of third period elements. Overall, this experiment aims to draw conclusions on periodic trends across the Periodic Table.
Experiment and Results Part I. The Behavior of the Metals of Groups I, II, and III a) i) Material and Methods: ii) Observations: iii) Equations: The materials used for this section were a one liter beaker, 0.1% phenolphthalein, sodium metal (Na), and potassium metal (K). In this section, the beaker was approximately filled 3/4 of the way with water. First, a small piece of sodium metal was dropped into the water, and after the reaction went through, 3-4 drops of phenolphthalein were added. In a second beaker with the same amount of water, a small piece of potassium metal was added, along with the same amount of phenolphthalein after the reaction. The reactions of both beakers were observed. When the sodium metal was added to the water, many bubbles quickly formed and the piece of Na floated to the top of the water, noticeably fizzing. After the phenolphthalein was added, the colorless solution changed to a light pink