All substances are homogeneous. Some mixtures are also homogeneous. Being so, it is difficult to distinguish mixtures and substances based on appearance. However, there are ways to tell if a sample is a mixture or a substance. The temperature of a liquid mixture changes during boiling but for a liquid substance, it does not. A solid mixture has portions that do not melt but a solid substance melts completely at a given time. From here, you can say that the more observations and characteristics you consider, the better you can classify them.
In this module, you will find out that substances may further be classified into two: compound and element. You will start with the primary characteristic that distinguishes them.Compounds Like mixtures, compounds are also made up of two or more components.
In module 3, you separated the components of seawater through distillation. One of the products obtained was distilled water. Also, you have identified distilled water as a substance.
How are elements different from compounds?
How are they similar?
In the video you will about to see, how to separate hydrogen and oxygen atoms of compound water.
This process is called electrolysis.
Q1. What happened when you placed a lighted match near the mouth of the test tube?
As you have seen from the video above, compounds are made up of components. These components are called the elements. Like compounds, the elements are also substances. However, unlike compounds, elements cannot be broken down into simpler substances. Chop a sample of an element; you still have the same substance after! Distill? You get the same! Electrolyze? Still the same!
Notice as well that the property of a compound is different from the properties of its constituent elements.
Elements
There are119 known elements. Each element has different set of properties. No two elements have the same set of properties. Just like the two elements that were generated in video above, hydrogen and oxygen. Even though they are both in gaseous state at room temperature, they behave differently when exposed to a flame or spark of flame. Hydrogen gives off a “pop” sound when ignited; while oxygen induces a brighter spark. This difference in behavior implies a difference in property. In effect, hydrogen and oxygen are different substances, or to be more specific, they are different elements.
119 is quite a big number! Thanks to the works of our early scientists, they were able to systematically organize all of the 119 elements in what we call the periodic table of elements or sometimes simply referred as periodic table. Amazingly, they were able to logically arrange the elements in the table enabling one to have an idea of the properties of several elements by knowing other elements related to them. This means that there is no need to memorize the periodic
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Q1. What are the symbols for elements with long names such as beryllium, phosphorus, germanium, and darmstatdtium?
a. Notice that most of the one-letter symbols are the first letters of these elements.
Q2. What are the symbols for boron, nitrogen, fluorine and vanadium?
b. For the two-letter symbols, most of them start with the first letter of the elements. Notice that the second letter in the symbol may be any letter found in the element’s name. Notice as well that only the first letter is capitalized for the two-letter symbols.
Q3. What are the symbols for lithium, chlorine, argon, calcium and manganese?
c. There are symbols that use letters that were taken from the ancient name of the element. Examples of ancient names are ferrum (iron), argentum (silver), hydrargyrum (mercury) and plumbum (lead).
Q4. What are the symbols for iron, silver, mercury, and lead?
d. In the earlier grade levels, you already encountered elements. You studied rocks and learned that some are composed of silicon and magnesium. Some even have gold.
Q5. What are the symbols for silicon, magnesium and gold?
f. When you were recycling materials, you segregated the objects according to what these are made of. Some of them are made from aluminum, copper, tin or carbon.
Q6. What are the symbols for these 4 elements?
g. In nutrition, you were advised to eat enough bananas because it is a good source of potassium.
Q7. What is the symbol for potassium?
h. In each box, you will find a number on top of each symbol. This is the atomic number. In the higher grade levels, you will learn what this number represents. For now, use it as a guide on how the elements are sequenced.
Q8. What is the element’s name and symbol that comes before titanium? How about that comes after barium?
i. Elements that are in the same column tend to have similar properties. For this, each column is called a family and has a family name. However, at this point, you will refer first to each family with their corresponding group number. Notice that the columns are numbered 1 to 18 from left to right.
Q9. In which group does each of the elements listed in Table 1 belongs to?
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There are other elements present in the food you eat —whether it is a natural food like bananas or those processed like banana chips, biscuits, milk, and juice. In nutrition, you have called them minerals. These are nutrients which the human body needs in order to function well. Some of these minerals are calcium, magnesium, zinc, and selenium. Find these elements in the periodic table. Can you name more? Did you find them in the periodic table?
Note that these minerals have to be taken in by the body in recommended amounts. Refer to Figure 3. How much calcium do you need to consume in a day? How about magnesium? Avoid taking in minerals beyond these recommended amounts. It may lead to sickness, and even death. Thus, it is imperative that you are aware of what makes up the food that you are eating. Also, make sure that you have a balanced diet. You may refer to Table 2 below for food sources of some minerals when preparing your meal
Figure 3. Recommended mineral intake (WHO, 2004)
Macrominerals
Calcium (Ca) Milk, cheese, canned fish with bones, sesame seeds, green leafy vegetables
Essential to formation and maintenance of bones and teeth; regulates nerve transmission, muscle contraction, and blood clotting. Rickets in children; diseases of the bones in adults such as softening of the bones and decrease in bone mass
Magnesium (Mg) Nuts, legumes, cereal grains, dark green vegetables, sea food, chocolate
Catalyst in the synthesis of energy-carrier molecules; involved in the synthesis of proteins and relaxation of muscles
Fluid loss due to too much alcohol intake; heart failure due to spasms
Potassium (K) Orange juice, bananas, dried fruits, potatoes
Maintains regular heartbeat, water balance and cell integrity; needed in nerve transmission, carbohydrate and protein metabolism
Sudden death during fasting, poor nerve function, irregular heart beat
Selenium (Se)
Liver, meat, grain, vegetables
Part of enzymes; antioxidant
Keshan disease (heart disease)
Sodium (Na)
Meat, table salt, salt- processed food
Regulates amount of body fluid; involved in nerve transmission
Headache, physical weakness, thirst, poor memory, appetite loss
Sulfur (S)
Some proteins
Component of biomolecules and ions
Zinc (Zn)
Liver, shellfish, meat, wheat germs, legumes
Part of insulin and some 154 enzymes
Anemia, stunted growth
Microminerals or Trace elements
Chromium (Cr)
Liver; animal and plant tissues
Needed for glucose utilization
Loss of insulin efficiency with age
Copper (Cu)
Liver, kidney, egg yolk, whole grains
Helps in the formation of hemoglobin; part of 11 enzymes
Rare
Fluorine (F)
Sea food, fluorinated drinking water
Strengthens bone and tooth structure
Dental decay
Iron (Fe)
Liver, meat, green leafy vegetables, whole grains, cocoa beans
Component of hemoglobin and myoglobin
Anemia, tiredness, and apathy
Iodine (I)
Sea food, iodized salts
Part of thyroxin, regulates rate of energy use
Goiter
Manganese (Mn)
Liver, kidney, wheat germ, legumes, nuts
Cofactor for a number of enzymes
Weight loss, occasional dermatitis
You can also find information about the contents of the food in its product label. Usually, they are written as Nutrition Facts and Ingredients.
The Nutrition Facts is a list of the different nutrients provided by the food product with their corresponding percentage share on the daily recommended dietary allowance. Refer to the figure on the right. Notice that some of these nutrients are elements such as calcium. Is this food a good source of calcium?
On the other hand, Ingredients give you a list of the materials that have been added to create the food product. These materials are the sources of the nutrients. These are the ones that are taken in by the body. Refer to the figure below. Find the ingredient ferrous sulfate. Ferrous is another word for iron. Refer to the figure above. This is the Nutrition Facts which corresponds to the food product having these ingredients. Find the nutrient iron. How much iron does this food product give as part of the recommended dietary allowance? From this product label, you can tell that you will be getting as much as 35% of iron that you need for the day and eaten mostly as ferrous sulfate. Notice that the name of the ingredient gave a clue as to which nutrient this ingredient contains.
Cereal drink
Ingredients:
sucrose, creamer (glucose syrup, hydrogenated palm kernel oil, sodium caseinate containing milk, sequestrants, emulsifiers, nature-identical flavors, sodium chloride, anticaking agents), maltodextrin, cereal flakes (wheat flour, rice flour, malt extract, sucrose, corn grits, acidity regulator), sweet whey powder, cocoa powder, iodized salt, thickener, artificial flavour, zinc sulfate, iron pyrophosphate.
May contain traces of soya.
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As you have learned from the activity above, the minerals listed in the Nutrition Facts as elements are present in the food as compounds. Thus, you are not eating the elements themselves.
A product label that lists sodium as a nutrient does not mean that you will be eating the element sodium. It means that the composition of one of the ingredients includes sodium. In the case of soy sauce, the ingredient is monosodium glutamate.
It is very rare and most of the time dangerous if you take in the element itself. In Activity 1, you have seen that water did not give off a “pop” sound nor induced a bright spark when exposed to a spark or flame, unlike its constituent elements hydrogen and oxygen, respectively. This means that the properties of compounds are different from the properties of the elements it is made up of. There are cases that the properties of a compound pose less risk than its constituent elements. An example is sodium and one of its compounds. Sodium is an element that flares when it comes in contact with water. Refer to the photo above. Imagine the danger that you are in to if you will be eating sodium as an element. However, sodium chloride, which is a compound made up of the elements sodium and chlorine, does not flare when it comes in contact with water. In fact, sodium chloride is sometimes used with water as common food ingredients. Perhaps, you are already familiar with this. Does table salt ring a bell? Sodium chloride is commonly called as table salt. As you know, it is safe to eat. Do take note though that it should be consumed in the right amount. Excessive consumption of sodium chloride may lead to kidney failure. From here comes the importance of reading product labels. This will let you know how much of a nutrient you get from a food product. It is also an advantage if you know the different names of the elements and compounds. Take the case of the food product label below.
Refer to the Nutrition Facts of the cereal product on the right. It tells that this cereal product provides the nutrient, sodium.
Now, refer to the Ingredients. Do you find any ingredient that could be a source of sodium? It may seem not, at first. However, knowing that the other name for sodium chloride is salt, you can now identify one source ingredient for the sodium that is listed in the Nutrition Facts.
Note that there are instances that the Nutrition Facts is incomplete. You may find an element unlisted but once you check the Ingredients, you can tell that the food product could be a source of that mineral. Refer to the label of the cereal drink you used in Activity 3. Is sodium listed in the Nutrition Facts? Is there an ingredient that could be a source of sodium? When you read product labels, make sure you do not miss out on these information. This will help you decide if the product is worth buying.
Any ingredient added to food should be safe to eat in terms of quality and quantity. By quality, these ingredients must be food grade. A substance undergoes a process before it becomes food grade. It is only after that, a substance may be safely added as a food ingredient. If it is a non-food grade substance then it should not be added to products that are meant to be ingested.
Refer to the product labels for a soy sauce and a lotion. Notice that potassium sorbate is a common ingredient. It has the same function for both products, that is, it acts as a preservative so the product would last longer. However, it is important to note that food grade potassium sorbate was added in soy sauce; while a non-food grade potassium sorbate was added in lotion.
You can safely ingest soy sauce but never ingest the lotion. Notice that the product label does not indicate if the ingredient is food grade or not. However, there are government agencies that make sure the food products that are sold in the market uses only food grade ingredients. Thus, it is safe to assume that food products consumed in the right amount will not pose any risk.
In the next activity, you will encounter another substance that is common to materials that are not meant to be ingested. However, this substance was made food grade before it was added as a food ingredient. This substance is iron. This food grade iron is sprayed onto the food or added as a powder to the mixture. Because it is the elemental iron that was added as a mixture, its properties are retained. One of these is its magnetic property. Thus, you can recover the iron present in the food product by using a magnet.
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Compounds are made up of elements.
Elements are the simplest form of matter.
Both elements and compounds are substances.
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As you have seen, elements are part of almost anything around us — food, clothes, rocks, and even this paper you are currently reading from. Elements are said to be the building blocks of matter. They are like blocks that you can put together and build something new. When you build something new from these elements, you call them as compounds.
With the 119 elements known, imagine how many combinations of elements you can make into compounds and how diverse can the materials around us be.
In the next module, you will learn more about the elements. You will work on samples of elements and explore their properties.
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