EIS 1: Exploring Properties of Elements
In this activity, you will be classifying and identifying elements based on their chemical properties. This will help you to understand why it is useful to know the chemical properties of elements.
Density is a measure of how heavy something is compared to how big it is. For example, 10 pounds of bricks weighs the same as 10 pounds of feathers, but the bricks are a lot more dense. We would need A LOT of feathers to make up 10 pounds, but not as many bricks.
In terms of the atomic property, density is a little weirder to think about. Since density depends on both volume and mass, and both of these things change as you go down (or across) the periodic table, you kind of have to make your best guess as to which one will change more. Going across the Periodic Table (lithium to fluorine—Li to F) isn’t as confusing, because things get smaller and heavier, both of which mean denser. Moving down the periodic table (lithium to cesium - Li to Cs), mass usually will change faster than size, so density will increase. However, you need to do an experiment to know for sure.
Flame color is a chemical property. It has to do with how electrons behave. You haven’t learned about it yet, but when electrons get excited (like when they get hot), they bounce up an energy level (the rings on the Bohr model). When they get un-excited (which happens really quickly, all on its own), it releases light. Depending on how big this energy gap is, the color of light will be different. Red light is low in energy, while blue and purple light is high in energy (it goes in rainbow order).
You can see very specific red or blue light, etc. (or all the colors) if you use special glasses to separate the light. When you look at a flame, on the other hand, you are seeing all of these colors combined. So, again, you have to do an experiment to know for sure what color flame something will have.
Melting point and boiling point are chemical properties. Melting point is the temperature at which something changes from a solid to a liquid. Boiling point is the temperature at which something changes from a liquid to a gas. This is related to the attraction between atoms. (You’ll learn more about this later on!).
For this activity, we will give you known data to compare your unknown samples to. If your unknown has a lot of the same properties as one of the known samples, there’s a good bet that your unknown is this know. For example, lithium has a low density and its flame is purple when you burn it. So, if your sample has a low density and its flame is purple when you burn it, it’s probably lithium! In other words, you get to be Sherlock Holmes, and we’ll give you your clues.
Density is a measure of how heavy something is compared to how big it is. For example, 10 pounds of bricks weighs the same as 10 pounds of feathers, but the bricks are a lot more dense. We would need A LOT of feathers to make up 10 pounds, but not as many bricks.
In terms of the atomic property, density is a little weirder to think about. Since density depends on both volume and mass, and both of these things change as you go down (or across) the periodic table, you kind of have to make your best guess as to which one will change more. Going across the Periodic Table (lithium to fluorine—Li to F) isn’t as confusing, because things get smaller and heavier, both of which mean denser. Moving down the periodic table (lithium to cesium - Li to Cs), mass usually will change faster than size, so density will increase. However, you need to do an experiment to know for sure.
Flame color is a chemical property. It has to do with how electrons behave. You haven’t learned about it yet, but when electrons get excited (like when they get hot), they bounce up an energy level (the rings on the Bohr model). When they get un-excited (which happens really quickly, all on its own), it releases light. Depending on how big this energy gap is, the color of light will be different. Red light is low in energy, while blue and purple light is high in energy (it goes in rainbow order).
You can see very specific red or blue light, etc. (or all the colors) if you use special glasses to separate the light. When you look at a flame, on the other hand, you are seeing all of these colors combined. So, again, you have to do an experiment to know for sure what color flame something will have.
Melting point and boiling point are chemical properties. Melting point is the temperature at which something changes from a solid to a liquid. Boiling point is the temperature at which something changes from a liquid to a gas. This is related to the attraction between atoms. (You’ll learn more about this later on!).
For this activity, we will give you known data to compare your unknown samples to. If your unknown has a lot of the same properties as one of the known samples, there’s a good bet that your unknown is this know. For example, lithium has a low density and its flame is purple when you burn it. So, if your sample has a low density and its flame is purple when you burn it, it’s probably lithium! In other words, you get to be Sherlock Holmes, and we’ll give you your clues.
Procedure
- Visit this site
- Drag unknown element 1 from its place on the test tube rack to the window labeled “density”. A box should pop up saying, “This element has ______ density.” Record this finding in the table below.
- Drag the same test tube from the density window to the flame color window. Record the observation in the table.
- Repeat this for the other windows and unknowns until the chart is complete.
- After you have filled out the chart for each element (and before you put each tube back in its spot on the test tube rack), click the name of the element to guess which one it is. The more similar the properties, the more likely it is that they’re the same element.
Data
Copy (or print!) the following table down in your notebook to work off of. Then fill in your answers in the form below to check your work.
| EIS 1 Worksheet Print! |
Review Questions
Content contributors: Emma Moulton