Purpose: After watching a video that introduces them to the periodic table, students will answer questions that prompt them to identify general patterns in the table. A second set of videos focused on reactivity will encourage students to use their observations to identify trends and predict behavior in reactivity among metals and nonmetals.
Approximate time: 50 minutes
Activity Guide for Students
Handouts showing the periodic table or a large periodic table wall chart
Classroom computer projector to show video clips demonstrating chemical reactivity
Directions for teachers:
In the first part of this activity, students will get to know the periodic table through “The Periodic Table Song,” various versions of which are available on YouTube. A new version of the song is at Periodic Table Song. Plan to play the song at least twice to get your students thinking about the table and its general set up. Allow students to listen generally once, then ask students to listen again and answer the questions provided. After the lesson, you could also share a classic version of the song by Tom Lehrer.
After students have completed the first set of questions, they will observe and predict trends in reactivity of metals and nonmetals based on the suggested videos below.
Have students create a data table to write down the physical properties of each metal element they will see in the video: lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca) and strontium (Sr). Students should include space to make observations of each metal’s reaction with water. Have students create a second data table to write down the physical properties of each nonmetal in the videos: chlorine (Cl), bromine (Br), iodine (I) and oxygen (O). Students should include space to make observations of each nonmetal’s reaction with aluminum.
Play the following suggested videos or similar video clips and ask students to answer the questions that follow.
Other optional videos:
If you have the resources and equipment to safely do so, you could demo some of these reactions in the classroom. But even without a live demo, students should be able to make observations about the physical properties of the elements and observe trends in reactivity.
Directions for students: After listening to “The Periodic Table Song,” answer the questions that follow.
1. What is the pattern you observe for the order in which the elements are presented during the song? List the first 12 elements mentioned in the song.
The periodic table is being read like a book: Elements are listed starting from the top, far left element (hydrogen) across the whole row before going down to the next row far left. The first 12 elements are: H, He, Li, Be, B, C, N, O, F, Ne, Na and Mg.
2. The atomic number defines the type of atom, or element, that exists. How does the number of protons, or the atomic number, differ from one element to the next in the song?
Each element mentioned has one more proton than the previous element mentioned.
3. What is the refrain of the song?
“This is the periodic table, noble gases stable, halogens and alkali react aggressively. Each period we’ll see new outer shells, while electrons are added moving to the right.”
4. What does the refrain tell you about the reactivity of noble gases? Where are noble gases located on the periodic table?
The rightmost column (noble gases) contains elements that have a stable configuration of electrons for each energy level, or row on the periodic table. Nobel gases do not generally give or accept any electrons, so they are nearly chemically inert.
5. Where are alkalies (metals) and halogens (nonmetals) located on the periodic table? Why do you think elements like the halogens and alkalies would react?
Alkali metals are in the leftmost column on the periodic table and halogens are to the left of the noble gases. Atoms in these columns react to become stable (have a lower energy state). Both the alkalies and the halogens react to become more like noble gases in terms of their number and configuration of electrons.
6. Given the long list of elements from the song, where do alkalies (metals) and halogens (nonmetals) always fall in relation to the closest noble gas in the list? How does the proximity to a noble gas affect how aggressively elements react?
Halogens are always the element before a noble gas and alkalies are always right after a noble gas. The closer the elements are to stability, the more aggressively they tend to react.
7. What does the refrain tell you will happen to the physical structure of the atoms as you go down a column, hopping from one period, or row, to the next? In your own words, what visual does the video use to show this trend?
The refrain says, “each period we’ll see new outer shells.” As you move down a column of the table, generally the element in the row below will have one more completely filled “shell” (energy level) of electrons than the one in the row above. The video shows a Bohr model of the atom, with a nucleus denoted by a red dot and shows electron shells being added as concentric circles, getting farther away from the nucleus.
8. What does the refrain tell you will happen to atoms as you go across a row, “moving to the right?” In your own words, what does the video use to show this trend?
The refrain says, “electrons are added moving to the right.” As you move to the right across a row, generally the element to the right will have one more electron in the outermost electron shell (energy level) than the previous element. The video shows a Bohr model with a nucleus denoted by a red dot and shows electrons being added to existing concentric circles around the nucleus.
Directions for students continued: Before watching the videos on reactivity, create a data table to write down the physical properties of each metal element you will see in the video: lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca) and strontium (Sr). Include space to make observations of each metal’s reaction with water. Create a second data table to write down the physical properties of each nonmetal in the videos: chlorine (Cl), bromine (Br), iodine (I) and oxygen (O). Also, include space to make observations of each nonmetal’s reaction with aluminum.
As you watch the videos, fill in your observation table based on what you observe. Then answer the questions that follow.
1. Based on your observations, list the metals in each of the following sets from least reactive to most reactive:
K, Na, Li
Li, Na, K
Sr, Ca, Mg
Mg, Ca, Sr
2. Based on your observations, list the following nonmetals from least reactive to most reactive:
Cl, Br, I
I, Br, Cl
3. Based on your observations and analysis, explain the general reactivity trend of metals as you go across a row from left to right on the periodic table. What about the trend as you go down a column on the periodic table?
Metals tend to get less reactive as you move across a period to the right and more reactive as you move down a column.
4. Based on your observations and analysis, explain the general reactivity trend of nonmetals as you go down a column on the periodic table?
Based on the reactivity trends of the halogens, nonmetals tend to be less reactive as you move down a column on the table.
5. In your experience with items made out of aluminum (aluminum cans, foil, etc.), how reactive is oxygen with aluminum? How do you think the reactivity of oxygen with aluminum would compare with the reactivity of fluorine with aluminum?
Aluminum reacts with oxygen over time, but it is a slow process. For example, an old aluminum can that has been sitting outside for a while can appear to have a rust-like layer on it. Based on the trend in nonmetal reactivity (the reactivity increases up a column), I would expect fluorine to be much more reactive with aluminum than oxygen would be with aluminum.
6. What do you predict is the general reactivity trend of nonmetals as you go across a row from left to right on the periodic table?
The reactivity of nonmetals would likely increase as you move across a period to the right.
7. What do you notice about the reactivity trends of metals compared with the reactivity trends of nonmetals?
The reactivity trends of metals are the opposite of the reactivity trends of nonmetals.
8. Atoms react to become more stable either losing or gaining (taking or sharing) electrons. Based on the proximity to a noble gas, do you think metals react by gaining or losing electrons? What about nonmetals?
Metals tend to lose electrons and nonmetals tend to gain electrons to become more stable (have an electron structure similar to a noble gas).
9. What patterns of reactivity would you expect from an element like silicon (Si)? Explain.
Silicon is the same number of elements away from the noble gas preceding it, Neon (Ne), as it is from the noble gas following it, Argon (Ar). It can probably gain or lose electrons to become stable, because it needs to gain or lose the same number of electrons to have a stable number (configuration) of electrons.
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