Objectives:
After performing this activity, you should be able to:
1. infer from given situations or observable events what matter is made of;
and
2. explain how these observed situations or events give evidence that matter is made up of tiny particles.
Materials Needed:
½ cup refined sugar
1 cup distilled or clean tap water 1 piece, 100-mL graduated cylinder 1 measuring cup (1 cup capacity)
1 piece transparent bottle (can hold one cup of water) or 250-mL beaker food coloring (blue, green, or red)
1 dropper
1 stirrer (plastic coffee stirrer or stirring rod)
Procedure:
Is this matter?
1. Using a clean and dry graduated cylinder, pour sugar until the 20 mL mark of the graduated cylinder.
2. Transfer the measured sugar into a 250-mL beaker or transparent bottle.
3. Measure 50 mL of distilled or clean tap water using graduated cylinder.
4. Add the 50 mL water to the sugar and mix thoroughly until all the sugar dissolves. Taste the resulting solution. (CAUTION: Do not taste anything in the laboratory unless specifically told to do so by your teacher)
Q1. What is the taste of the resulting mixture?
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Q2. Think about sugar and water as made up of tiny particles. With your groupmates, discuss and give your reason(s) for the observations you made in Q1. You may draw illustrations to further explain your reason(s).
5. Transfer the sugar mixture into a graduated cylinder.
Q3. What is the volume of the sugar and water mixture?
Q4. Is the volume of the resulting sugar mixture equal, more than or less than the sum (20 mL sugar + 50 mL water) of the volumes of the unmixed sugar and water?
Q5. Think about sugar and water as made up of tiny particles. With your groupmates, discuss and give your reason(s) for the observations you made in Q3. You may draw illustrations to further explain your reason(s).
6. Pour one cup of tap water into a transparent glass bottle.
7. Add one small drop of food coloring slowly along the side of the transparent bottle.
Q6. Describe what you observe after adding the food coloring.
8. Set aside the bottle with food coloring in a locker or corner of your room without disturbing the setup. Describe the appearance of the contents of the bottle after one day. Compare it with the appearance when you left the bottle the previous day.
Q7. What happens to the food coloring dropped in the bottle containing water? Write all your observations in your notebook.
Q8. Think about food coloring and water as made up of particles. With your groupmates, discuss and give your reason(s) for the observations you made in Q6. You may draw illustrations to further explain your reason(s).
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Studying about what matter is made of involves dealing with very small
“particles” beyond what your eyes can see. In fact, the ancient Greek philosophers proposed ideas about what matter was made of. Almost 2,500 years ago, Leucippus and his disciple, Democritus believed that nature consisted of two things, “atoms and the void that surrounds them” (Knieram, 1995-2013). They believed that “atoms are physically, but not geometrically, indivisible.” For Democritus, atoms are indestructible and completely full, so there is no empty space. Both Leucippus and Democritus had the idea that there are many different kinds of atoms and each of them had specific shape and size and that all atoms move randomly around in space. However they did not give an explanation for the motion of atoms. (Knieram, 1995-2013).
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Democritus believed that any piece of matter can be divided and subdivided into very small particles but that this process ended at some point when a piece is reached that could not be further divided. He called this particle, atomos, a Greek word which means indivisible particle. Democritus’ ideas about the atom were later challenged by other Greek philosophers, most strongly by Aristotle.
The idea of the atom was not further explored until a little over two centuries ago when John Dalton presented concrete evidence that all matter is made of very small particles called atoms. An atom is the smallest particle of an element that has all the properties of the element. Today, we know that although atoms are very small, they are not indivisible as Democritus thought, rather they consist of still smaller particles, Democritus was right in one aspect of his belief, that is, atoms are the smallest particles of which substances are made. In Grade 7, you learned about elements. Atoms of most elements have the ability to combine with other atoms.
Different elements have different properties because the combining atoms are different and the way the atoms are joined together are different. In Module 2 of this quarter, you will learn about how the model of the atom evolved until the present time. You will also learn that an atom is made of even smaller parts.
A molecule is a particle consisting of two or more atoms combined together in a specific arrangement. It is an electrically neutral particle. It is the smallest particle of an element or compound that can exist independently. For example, a molecule of water consists of an oxygen atom combined with two hydrogen atoms.
Atoms of the same element can also combine to form a molecule. For example, oxygen in the air consist of oxygen molecules which are made up of two oxygen atoms.
Atoms are too small to observe. These particles cannot be seen under the high-powered light microscopes used in school laboratories. The size of an atom is measured in angstroms. One angstrom is a unit of length equal to one ten millionth of a millimetre.
The best light microscope can magnify an image only about 1,500 times.
Electron microscopes create a highly magnified image of up to 1 million times. The scanning tunneling microscope (STM) allows scientists to view and scan the surface of very small particles like atoms. It can magnify an image 10 million times. The STM creates a profile of the surface of an atom and then a computer-generated model or contour map is produced. So, only a model of the surface of an atom is generated by a computer when a scanning tunnelling microscope is used. The picture of atoms generated is unlike the picture we take with our cameras.
In Activity 2, when you mixed sugar and water and tasted the resulting solution, it tasted sweet because sugar is still present, though you cannot see the sugar anymore. The volume of the mixture is less than the sum of the volumes of the unmixed sugar and water. Why is this so? The water is made of tiny particles, molecules, with spaces between them. Sugar is also made up of molecules bigger than the molecules of water. The water molecules could fit in the spaces between the sugar molecules or vise versa.
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Figure 1(b). Blown-up image of a portion of Figure 1a. Dots are more conspicuous.
Figure 1(a). Continuous image of a pointillist painting
Photo courtesy of Maria Laura V. Ginoy
A good analogy to consider related to matter being composed of tiny particles is the pointillist style of painting. The images in a pointillist painting appear continuous but if one looks closely, the images are actually made of small dots.
Pointillism is a method of painting using dots to come up with various effects. The dots are placed singly, in rows, or randomly. These dots can also be in groups or they can be overlapping. They can be either uniform or varied in size in the same painting. Matter is similarly assembled, with atoms of different elements combining in various ways to give a tremendous variety of substances.
In Figure 1(a), the image of Dolores F. Hernandez, founding Director of the Science Education Center, now University of the Philippines National Institute for Science and Mathematics Education Development was done through pointillist painting. The image appears continuous. In Figure 1(b), a portion of the painting (boxed in Figure 1a) is blown up to show that the continuous image actually consists of dots. The lightness and darkness of the pigments give volume to the image in order to show smoothness. Similarly, matter, which appears to be continuous like the image in Figure 1(a) is made up of very small particles that cannot be seen with the unaided eye.
In the next activity, you will observe a situation to infer that particles of matter are moving and there are spaces between them.
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