Periodic+Table+Trends+with+Alkali+Metals

Aubree Niemiec __aln5076@psu.edu __ Jessica Mitchell __jjm5363@psu.edu __
 * Periodic Table Trends with Alkali Metals **

Seventh Grade - Periodic Table Trends with Alkali Metals
 * Grade Level - Topic **

- Pennsylvania State Standard 3.4.7.A - Describe concepts about the structure and properties of matter; identify elements as basic building blocks of matter that cannot be broken down chemically, distinguish compounds from mixtures, describe and conduct experiments that identify chemical and physical properties. - Pennsylvania State Standard 3.7.7.A - Describe the safe and appropriate use of tools, materials and techniques to answer questions and solve problems; describe safe procedures for using tools and materials. - National Standards Table 6.2 - properties and changes of properties in matter.
 * National and State Standards **

At the end of this lesson students will be able to: Identify periodic table trends as you move down Group 1 Predict what occurs when alkali metals come in contact with water Explain why the reaction occurs
 * Objectives **

<span style="color: black; font-family: 'Times New Roman',serif;"> Group 1 of the periodic table is known as the alkali metals and they have only one electron in their outer most shell. There are several trends to the periodic table but we are only going to focus on a few of them. The first trend is atomic size. The atomic size depends on how close or far away the valence electrons are from the nucleus. Thus, if the electrons are close to the nucleus the atom will be small and vice versa. This is demonstrated on the periodic table by atomic size increasing as you travel down a column. As you move down a group, the number of shielding electrons increases with the nuclear charge, so more energy levels are created, allowing the electrons to stay further away from the nucleus (bigger atomic size). Shielding electrons are the electrons in the energy levels between the nucleus and the valence electrons; shield valence electrons from attraction of the nucleus. Another trend that builds off of this one is ionization energy, which refers to the energy required to remove an electron. As previously stated, as you move down the alkali metal group, the electrons get further away from the nucleus; therefore, it is easier to lose electrons (low ionization energy). With alkali metals having only one electron in their outer most shell, meaning they are very unstable, they are a lot more reactive. <span style="color: black; font-family: 'Times New Roman',serif;"> As you move down the column, the alkali metal reaction with water becomes more violent. In each of the cases with the alkali metals the reaction is removing one electron after the other, one electron from the outer shell of the atom, the bigger the atom, the easier it is to remove the electron.
 * <span style="color: black; font-family: 'Times New Roman',serif;">Content Explanation **

<span style="color: black; font-family: 'Times New Roman',serif;">Flame colors: <span style="color: black; font-family: 'Times New Roman',serif;">Lithium - Crimson Red <span style="color: black; font-family: 'Times New Roman',serif;">Sodium - Red/Yellow <span style="color: black; font-family: 'Times New Roman',serif;">Potassium - Blue/Lilac <span style="color: black; font-family: 'Times New Roman',serif;">*Note: Be sure to specify to students that the blue flame is hotter than the red flame.

<span style="color: black; font-family: 'Times New Roman',serif;">They all react with water to form alkaline hydroxides. The vigor of the reaction increases down the group. They only have one electron in their outermost electron shell. <span style="color: black; font-family: 'Times New Roman',serif;">Alkali Metal + Water à <span style="color: black; font-family: 'Times New Roman',serif;"> Alkali Metal Hydroxide + Hydrogen Gas

<span style="color: black; font-family: 'Times New Roman',serif;">There will be demonstrations of the addition of certain alkali metals with water. This creates explosions and fire, the severity depends on how much of the alkali metal you add and which metal it is. Students should be wearing safety goggles at all times during the experiment, and the beakers with water need plate glass to cover them.
 * <span style="color: black; font-family: 'Times New Roman',serif;">Administrative Considerations **

<span style="color: black; font-family: 'Times New Roman',serif;">- Vinegar <span style="color: black; font-family: 'Times New Roman',serif;">- Pure Li pellets <span style="color: black; font-family: 'Times New Roman',serif;">- Pure Na pellets <span style="color: black; font-family: 'Times New Roman',serif;">- Pure K pellets <span style="color: black; font-family: 'Times New Roman',serif;">- (4) Beakers with water <span style="color: black; font-family: 'Times New Roman',serif;">- (6) Safety Goggles <span style="color: black; font-family: 'Times New Roman',serif;">- (2) Tongs <span style="color: black; font-family: 'Times New Roman',serif;">- (25) Copies of the Periodic Table <span style="color: black; font-family: 'Times New Roman',serif;">- Pictures of the atomic structure depicting the size of the Group 1 elements
 * <span style="color: black; font-family: 'Times New Roman',serif;">Materials, Equipment, and Set-Up **
 * <span style="color: black; font-family: 'Times New Roman',serif;">- **<span style="color: black; font-family: 'Times New Roman',serif;">Baking soda

<span style="color: black; font-family: 'Times New Roman',serif;">- (Begin class with a demonstration of adding vinegar to baking soda) <span style="color: black; font-family: 'Times New Roman',serif;">- Ask students if they know what type of reaction they just witnessed <span style="color: black; font-family: 'Times New Roman',serif;">- What is the difference between a chemical and physical change? (Have students define both and provide examples of the two) <span style="color: black; font-family: 'Times New Roman',serif;">- We will present the students with individual copies of the periodic table and then ask them if they know why it has the shape it has <span style="color: black; font-family: 'Times New Roman',serif;">- Sodium will be added to water first for the students to just observe in order to give them a basis to make scientific predictions for how lithium and potassium will react <span style="color: black; font-family: 'Times New Roman',serif;">- After the sodium reaction, the teacher will ask the students to predict what will occur when lithium and potassium are added to water <span style="color: black; font-family: 'Times New Roman',serif;">- The students will write down their predictions and discuss with classmate <span style="color: black; font-family: 'Times New Roman',serif;">- The teacher will be at the front of the class for the demonstration <span style="color: black; font-family: 'Times New Roman',serif;">- While doing the experiment the chemicals and water bath will be contained either behind a clear shield or sitting in a clear container (we will be using a beaker with the top covered with a glass plate, leaving a small portion uncovered for the smoke to escape) <span style="color: black; font-family: 'Times New Roman',serif;">- A specified amount of each chemical will be added separately one at a time to the water bath and the students will observe what occurs and record their observation <span style="color: black; font-family: 'Times New Roman',serif;">- Students will be asked to explain if their predictions were correct <span style="color: black; font-family: 'Times New Roman',serif;">- The periodic table trends will then be introduced (or reviewed if they have already dealt with it) and discussed with the students, using the periodic table, alkali metals, and pictures of atoms as references <span style="color: black; font-family: 'Times New Roman',serif;">- The students will then be asked to explain again what they saw and why
 * <span style="color: black; font-family: 'Times New Roman',serif;">Body of the Lesson **
 * <span style="color: black; font-family: 'Times New Roman',serif;">Predict **<span style="color: black; font-family: 'Times New Roman',serif;">(5 minutes)
 * <span style="color: black; font-family: 'Times New Roman',serif;">Observe **<span style="color: black; font-family: 'Times New Roman',serif;">(5 minutes)
 * <span style="color: black; font-family: 'Times New Roman',serif;">Explain **<span style="color: black; font-family: 'Times New Roman',serif;">(10 minutes)