My best three posts are:
- http://rose-science-blog.blogspot.com/2011/03/chemical-changes.html
- http://rose-science-blog.blogspot.com/2011/03/acids-and-alkalis.html
- http://rose-science-blog.blogspot.com/2011/04/osmosis-part-of-diffusion.html
Wednesday, May 4, 2011
Thursday, April 14, 2011
Osmosis a Part of Diffusion?
Headline: Osmosis a Part of Diffusion?
Today, we went through Diffusion and Osmosis which is under the topic, Transport in Living Things. People usually think that osmosis and diffusion work in the same way. Actually, osmosis and diffusion are different from one another. Osmosis is a type of diffusion.
I learnt that diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. As for osmosis, it is the net movement of water molecules from a region of higher concentration of water molecules to a region of lower concentration of water molecules through a partially-permeable membrane.
The 3 differences between osmosis and diffusion are:
1. Diffusion can occur in solid, liquid or gaseous state but osmosis can only occur in the liquid state.
I also learnt that both osmosis and diffusion occur in living organisms. For instance, diffusion of gases can happen in both plants and animals. In addition, diffusion of digested food into the bloodstream from the small intestine also occurs in animals. As for osmosis, it occurs in both plants and animals cells. The membranes in the cells are partially permeable.
When the concentration of water molecules outside the cells are lower than the water molecules in the cells, the water in the cells will leave through osmosis and causes the plant cells to turn flaccid and causes the animals cells to shrivel up. As for when the water molecules outside the cells are higher than the water molecules in the cells, the water will go in the cells by osmosis and causes the plant cells to turn flaccid and causes the animal cells to swell and burst.
Today, we went through Diffusion and Osmosis which is under the topic, Transport in Living Things. People usually think that osmosis and diffusion work in the same way. Actually, osmosis and diffusion are different from one another. Osmosis is a type of diffusion.
I learnt that diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. As for osmosis, it is the net movement of water molecules from a region of higher concentration of water molecules to a region of lower concentration of water molecules through a partially-permeable membrane.
The 3 differences between osmosis and diffusion are:
1. Diffusion can occur in solid, liquid or gaseous state but osmosis can only occur in the liquid state.
- Diffusion in solid (e.g. copper (II) sulfate crystals being embedded on colourless agar)
- Diffusion in liquid (e.g. crystals of potassium permanganate diffuse in liquid)
- Diffusion in gas (e.g. the scent of perfume in the air)
- In some cases, both big and small molecules are able to pass through the partially-permeable membrane in diffusion.
- Only small water molecules are able to pass through the partially-permeable membrane in osmosis.
I also learnt that both osmosis and diffusion occur in living organisms. For instance, diffusion of gases can happen in both plants and animals. In addition, diffusion of digested food into the bloodstream from the small intestine also occurs in animals. As for osmosis, it occurs in both plants and animals cells. The membranes in the cells are partially permeable.
When the concentration of water molecules outside the cells are lower than the water molecules in the cells, the water in the cells will leave through osmosis and causes the plant cells to turn flaccid and causes the animals cells to shrivel up. As for when the water molecules outside the cells are higher than the water molecules in the cells, the water will go in the cells by osmosis and causes the plant cells to turn flaccid and causes the animal cells to swell and burst.
(Example of plant cells undergoing osmosis)
Sources: Google Images
Tuesday, April 5, 2011
Continuation of Acids and Alkali Worksheet
Headline: Continuation of Acids and Alkali Worksheet.
In today's Science lesson, we went through the worksheet on acids and alkalis which we had gone through part of it yesterday.
I learnt that:
In today's Science lesson, we went through the worksheet on acids and alkalis which we had gone through part of it yesterday.
I learnt that:
- In car engines, it is very unlikely for the measurement of pH to be done
- The acid in car battery is very acidic, which have a pH of 1
- Distilled water is neutral with a pH of 7
- The alkali in potassium hydroxide is very alkaline as it has a pH of 13
- When the universal indicator is added to an acid, the colour of it will first be green, then change to yellow, then orange and then red
- As for when the universal indicator is added to a very strong alkali, with a pH of 14, it will turn violet in colour
(Universal indicator with an alkali of pH 13)
(Universal Indicator)
Sources: Google Images
Monday, April 4, 2011
Acids and Alkalis Worksheet
Headline: Acids and Alkalis Worksheet.
For today's Science lesson, we went through the acids and alkalis worksheet which we had completed before this lesson.
I learnt that:
For today's Science lesson, we went through the acids and alkalis worksheet which we had completed before this lesson.
I learnt that:
- Baking powder is known as sodium carbonate
- When you have gastric pains, acids are being produced in your body
- Calcium hydroxide is used to neutralise the acids in the water
- Ammonium is used to describe salt while ammonia is used to describe gas
- Sulfuric acid is used to remove rust from iron and steel objects in industry
- Nitric acid is used in making explosive
- Potassium hydroxide is an ingredient in paint removers
- Limewater is known as calcium hydroxide
(Baking Powder - Sodium carbonate)
Sources: Google Images
Friday, April 1, 2011
Research
In this Science lesson, we were given time to work on our Scientific Thinking Project research. For our group, we divided the tasks so that each of us has a specific work to accomplish.
I learnt that there are food, such as carrots, coals, lemons, etc., that are able to aid in the reproduction of the bacteria. Well, my task was to research on carrots and my other teammates are tasked to research on other food for the bacteria. We have to research on them so that the results of our experiments would be better and more accurate.
I also learnt that carrots are carriers for bacteria contaminants due to them being exposed during handling, packaging, etc. I also found out that E.coli, bacteria that is used in our experiment, can contaminate a fresh and preserved product which in turn can cause us to have illnesses.
I learnt that there are food, such as carrots, coals, lemons, etc., that are able to aid in the reproduction of the bacteria. Well, my task was to research on carrots and my other teammates are tasked to research on other food for the bacteria. We have to research on them so that the results of our experiments would be better and more accurate.
I also learnt that carrots are carriers for bacteria contaminants due to them being exposed during handling, packaging, etc. I also found out that E.coli, bacteria that is used in our experiment, can contaminate a fresh and preserved product which in turn can cause us to have illnesses.
(Carrots)
Sources: Google Images, http://www.livestrong.com/article/170387-carrots-food-poisoning/
Thursday, March 31, 2011
Going Through Worksheets
In today's Science lesson, we went through worksheets which we had completed in the last few days. The worksheets were on equations of acids and alkalis and chapter 14 workbook, Changing Matter.
3 Thoughts:
1) The meaning of decomposition is known as breakdown and not combine. Examples of substances which undergo decomposition in the presence of heat are calcium carbonate, copper carbonate and sugar.
2) I learnt that producing light in a light bulb is a physical change as the filament in the light bulb is heated up, and electrical energy is converted to heat and light energy. In addition, the change is reversible and no new substances are formed.
3) In the reaction of acids and metal carbonates or reactive metals, chemical salts are always formed. We name the salts based on the types of acids and metals used at the start of the experiment. For example, when sodium and hydrochloric acid is being mixed together, the salt formed is called sodium (follows the name of the reactive metal used) chloride (known as the last name which is based on the type of acid used).
2 Questions:
1) Does decomposition occurs at a specific temperature?
2) The changing of energy from one form to another is not a chemical change right?
1 Useful application:
1) By knowing the names of the salts produce through chemical reactions, we are able to know which substances are given out in the different types of reactions.
Sources: Google Images
3 Thoughts:
1) The meaning of decomposition is known as breakdown and not combine. Examples of substances which undergo decomposition in the presence of heat are calcium carbonate, copper carbonate and sugar.
2) I learnt that producing light in a light bulb is a physical change as the filament in the light bulb is heated up, and electrical energy is converted to heat and light energy. In addition, the change is reversible and no new substances are formed.
3) In the reaction of acids and metal carbonates or reactive metals, chemical salts are always formed. We name the salts based on the types of acids and metals used at the start of the experiment. For example, when sodium and hydrochloric acid is being mixed together, the salt formed is called sodium (follows the name of the reactive metal used) chloride (known as the last name which is based on the type of acid used).
2 Questions:
1) Does decomposition occurs at a specific temperature?
2) The changing of energy from one form to another is not a chemical change right?
1 Useful application:
1) By knowing the names of the salts produce through chemical reactions, we are able to know which substances are given out in the different types of reactions.
(Few examples of the equations on the reactions of acids and reactive metals)
Monday, March 28, 2011
Video and Worksheet
Today, Mdm Riza showed us a video on the reaction of zinc with hydrochloric acid as the experiment we had done before, by mixing both the substances had failed. The inflated balloons in the video showed us that gas is produced during the reaction. We then had to complete a worksheet based on what we saw from the video.
I learnt that when zinc (reactive metal) mixes with hydrochloric acid, they produce hydrogen gas that caused both the balloons to be inflated. But the rate at which the balloons are inflating is different from one another. I think it is because of the different amount of the zinc and hydrochloric acid in both the conical flasks. I wonder if the balloons would burst if the reaction was stronger.
I also learnt that effervescence is a process in which bubbles are continuously given off by the reaction in the liquid at a very fast rate.
I learnt that when zinc (reactive metal) mixes with hydrochloric acid, they produce hydrogen gas that caused both the balloons to be inflated. But the rate at which the balloons are inflating is different from one another. I think it is because of the different amount of the zinc and hydrochloric acid in both the conical flasks. I wonder if the balloons would burst if the reaction was stronger.
I also learnt that effervescence is a process in which bubbles are continuously given off by the reaction in the liquid at a very fast rate.
(Reaction of zinc and hydrochloric acid that causes the balloons to be inflated)
Sources: Google Images
Monday, March 21, 2011
Digestion
Headline: Digestion.
In today's Science lesson, we went through the digestion worksheets which had to be completed during the March holiday. Digestion occurs in every human being. It is a process whereby large complex food molecules are broken down into smaller, simpler, soluble and diffusible molecules so that nutrients in the food can be absorbed by the body.
I learnt that there are two main processes in digestion, they are known as the physical and chemical digestion. When food is broken down into smaller pieces and its surface area increases, it is called a physical change. It is only known as a chemical digestion when large, complex food molecules are broken down into smaller, simpler, soluble and diffusible food molecules with the help of enzymes.
I learnt that special types of proteins, known as enzymes, are produced by our body so as to speed up specific chemical reactions. There are different types of enzymes called amylase (breaks down starch into maltose), maltase (breaks down maltose into glucose), protease (breaks down proteins into amino acids) and lipase (breaks down fats into fatty acids and glycerol).
Lastly, I also learnt that many athletes consume fruits such as bananas before a strenuous activity as they need energy and fruits, like bananas, are rich in sugar. The sugar can be easily digested and is able to provide instant energy for the athletes.
In today's Science lesson, we went through the digestion worksheets which had to be completed during the March holiday. Digestion occurs in every human being. It is a process whereby large complex food molecules are broken down into smaller, simpler, soluble and diffusible molecules so that nutrients in the food can be absorbed by the body.
I learnt that there are two main processes in digestion, they are known as the physical and chemical digestion. When food is broken down into smaller pieces and its surface area increases, it is called a physical change. It is only known as a chemical digestion when large, complex food molecules are broken down into smaller, simpler, soluble and diffusible food molecules with the help of enzymes.
I learnt that special types of proteins, known as enzymes, are produced by our body so as to speed up specific chemical reactions. There are different types of enzymes called amylase (breaks down starch into maltose), maltase (breaks down maltose into glucose), protease (breaks down proteins into amino acids) and lipase (breaks down fats into fatty acids and glycerol).
Lastly, I also learnt that many athletes consume fruits such as bananas before a strenuous activity as they need energy and fruits, like bananas, are rich in sugar. The sugar can be easily digested and is able to provide instant energy for the athletes.
(Example of the human digestion system)
Sources: Google Images
Thursday, March 10, 2011
Acids and Alkalis
Today, we were being taught on a new chapter, acids and alkalis. There are also many concepts and formulae that have to be learnt and memorised. Hence, we have to pay close attention to what Mdm Riza is teaching us as the concepts learnt may be tested in our examinations. We had also done quite a number of experiments in today's Science lesson.
I used to think that acids and alkalis are both the same. But now I think that they are DIFFERENT from one another in terms of their definitions and properties. An acid is a substance which is diluted in water to form solution and hydrogen ions are produced. The higher the amount of hydrogen ions, the stronger the acid is. The acid properties are present only when acids are dissolved in water. As for alkalis, they produce hydroxide ions when they are being dissolved in water. The stronger the alkalis, the higher the amount of hydroxide ions present. The three main differences between acids and alkalis are:
I used to think that only litmus paper test that can help us differentiate between acids and alkalis. But now I think that there are also many other indicators that will tell us which are acids and which are alkalis. Other examples of indicators are:
I used to think that acids and alkalis are both the same. But now I think that they are DIFFERENT from one another in terms of their definitions and properties. An acid is a substance which is diluted in water to form solution and hydrogen ions are produced. The higher the amount of hydrogen ions, the stronger the acid is. The acid properties are present only when acids are dissolved in water. As for alkalis, they produce hydroxide ions when they are being dissolved in water. The stronger the alkalis, the higher the amount of hydroxide ions present. The three main differences between acids and alkalis are:
- Acids have a sour taste but alkalis have a bitter taste
- Acids turn moist blue litmus paper red, while alkalis turn moist red litmus paper blue
- Acids have a pH value lesser than 7. However, alkalis have a pH value more than 7
I used to think that only litmus paper test that can help us differentiate between acids and alkalis. But now I think that there are also many other indicators that will tell us which are acids and which are alkalis. Other examples of indicators are:
- Universal indicator - turns into different colours, where each colour corresponds to a pH value, when it is added to different substances
- Phenolphthalein - use best on indicating alkalis as it changes to pink when alkalis are added to it. Stays colourless when being mixed with acidic/neutral substances
- Methyl orange - changes into yellow when being mixed with alkalis but turns red when acids are mixed into it
- Rose petals (made from plants)
- Red cabbage (made from plants) - blue (neutral), red (acidic), yellow (alkaline)
(Example of litmus paper test)
(Example of the pH scale)
Sources: Google Images
Monday, March 7, 2011
Chemical Change - Good or Bad?
Today's Science lesson, we discussed about the good and bad points of chemical changes and did some experiments on heating matters so as to see their reactions.
I used to think that when we heat sugar (white crystals), it would melt and would eventually turn into a colourless liquid and evaporate. Of course, I was wrong. But now I think that when we heat sugar (white crystals), it will melt and then turn into a black solid. In addition, a sweet smell will evolve.
I used to think that chemical changes usually have advantages and do not have any disadvantage on us or to the environment. But now I think that chemical changes have both advantages and disadvantages. Example of advantages in chemical changes is that they allow us to produce products, like medicines and petrol, which we can use in our daily lives. As for the example on disadvantages in chemical changes is that they may produce products, such as chemicals, that will cause pollutions and bring harm and damage to living and non-living things respectively.
Sources: Google Images
I used to think that when we heat sugar (white crystals), it would melt and would eventually turn into a colourless liquid and evaporate. Of course, I was wrong. But now I think that when we heat sugar (white crystals), it will melt and then turn into a black solid. In addition, a sweet smell will evolve.
I used to think that chemical changes usually have advantages and do not have any disadvantage on us or to the environment. But now I think that chemical changes have both advantages and disadvantages. Example of advantages in chemical changes is that they allow us to produce products, like medicines and petrol, which we can use in our daily lives. As for the example on disadvantages in chemical changes is that they may produce products, such as chemicals, that will cause pollutions and bring harm and damage to living and non-living things respectively.
(Sugar heated and turned into black solid)
Sources: Google Images
Friday, March 4, 2011
Science Common Test 1
Headline: Science Common Test 1.
Our common test paper was given back to us during today's Science lesson. Then, we went through the answers so as to correct our mistakes and also to check if our paper has been marked correctly.
After going through the paper, I learnt that:
Our common test paper was given back to us during today's Science lesson. Then, we went through the answers so as to correct our mistakes and also to check if our paper has been marked correctly.
After going through the paper, I learnt that:
- The smallest particle in an element is an atom while the smallest particle in a compound is a molecule. This is because element is a substance which cannot be broken down further by chemical methods and thus, its atoms stand on its own. As for compound, it is a substance which is made up of two or more different elements chemically combined together. Hence, its atoms are also combined together to form a molecule.
- The number of neutrons in the same type of atoms can differ from one another. For example, the number of neutrons in carbon (an element) can be 6 or 7.
- An atom is electrically neutral as the number of protons which have a positive charge of 1 is equal to the number of electrons which have a negative charge of 1.
(Atoms)
(Molecules)
Sources: Google Images
Tuesday, March 1, 2011
Chemical Changes
Well, we started off with a new topic, Chemical Changes, today. There are many concepts in this chapter that are very complicated. But after this lesson, I managed to get a better understanding on what the topic is all about and remember most of the concepts and ideas being taught to us.
3 Thoughts:
1) A chemical change is permanent where new substance is formed. The change is usually irreversible and a chemical reaction will always take place. A chemical reaction is a process whereby reactants (substances that are used for the reaction) are changed into new substances, also known as, products (substances formed). In addition, during a chemical reaction, no substances are destroyed or created. The atoms in them only re-arranged themselves so as to form new products.
2) A chemical reaction can be represented using equation. The equation can be written using words (word equation) or chemical formulae (chemical equation). Information on identity of reactants and the final products using chemical formulae and possible reaction conditions (e.g. temperature, physical state, etc.) are provided in a typical chemical equation. We can only say about the quantities involved in a chemical reaction when the equation is balanced. By balancing a chemical equation, we have to place numbers in front of the formulae of the substances in the equation.
3) There are four types of interactions which involve in chemical reaction. The four types are:
2 Questions:
1) Why electrolysis can also be a physical change?
2) When there is a plus (+) sign at the left hand side of the chemical equation, then can it be eliminated from the right hand side? Or must the plus (+) sign still remains on the right side?
1 Useful application:
1) Chemical changes help us understand more about the things happening to us in our daily lives and we are also able to know what are the changes and interactions that are going on around us.
3 Thoughts:
1) A chemical change is permanent where new substance is formed. The change is usually irreversible and a chemical reaction will always take place. A chemical reaction is a process whereby reactants (substances that are used for the reaction) are changed into new substances, also known as, products (substances formed). In addition, during a chemical reaction, no substances are destroyed or created. The atoms in them only re-arranged themselves so as to form new products.
2) A chemical reaction can be represented using equation. The equation can be written using words (word equation) or chemical formulae (chemical equation). Information on identity of reactants and the final products using chemical formulae and possible reaction conditions (e.g. temperature, physical state, etc.) are provided in a typical chemical equation. We can only say about the quantities involved in a chemical reaction when the equation is balanced. By balancing a chemical equation, we have to place numbers in front of the formulae of the substances in the equation.
3) There are four types of interactions which involve in chemical reaction. The four types are:
- Interaction between matter and heat (E.g. Combustion, Combination and Thermal Decomposition)
- Interaction between matter and light (E.g. Photosynthesis and Photography)
- Interaction between matter and electricity (E.g. Electrolysis)
- Interaction between matter and another matter (E.g. Digestion, Neutralization and Rusting)
2 Questions:
1) Why electrolysis can also be a physical change?
2) When there is a plus (+) sign at the left hand side of the chemical equation, then can it be eliminated from the right hand side? Or must the plus (+) sign still remains on the right side?
1 Useful application:
1) Chemical changes help us understand more about the things happening to us in our daily lives and we are also able to know what are the changes and interactions that are going on around us.
(Example of a chemical reaction where atoms re-arranged themselves)
(Example of a chemical equation)
(Example of a chemical reaction - Combustion)
Sources: Google Images
Monday, February 21, 2011
Preparation for Common Test
Headline: Preparation for Common Test.
Well, for today's lesson, we went through worksheets again so as to prepare us for the coming common test and correct the mistakes we had made.
I have learnt that the part of an atom which contains the protons and neutrons is called nucleon. The nucleon is positively charged and is densely concentrated in the centre of an atom.
I have also learnt that atoms usually gain or lose electrons but not the protons and neutrons as the protons and neutrons are found in the inner area of the atom. Thus, the electrons will be easier to be attracted by other atoms than the subatomic particles found in the inner area.
I learnt that the similarity between sulfur molecule and sulfur dioxide molecule is that both molecules are made up of more than one atom. As for their difference is that sulfur molecule contains one type of atoms but sulfur dioxide molecule has more than one type of atoms.
Well, for today's lesson, we went through worksheets again so as to prepare us for the coming common test and correct the mistakes we had made.
I have learnt that the part of an atom which contains the protons and neutrons is called nucleon. The nucleon is positively charged and is densely concentrated in the centre of an atom.
I have also learnt that atoms usually gain or lose electrons but not the protons and neutrons as the protons and neutrons are found in the inner area of the atom. Thus, the electrons will be easier to be attracted by other atoms than the subatomic particles found in the inner area.
I learnt that the similarity between sulfur molecule and sulfur dioxide molecule is that both molecules are made up of more than one atom. As for their difference is that sulfur molecule contains one type of atoms but sulfur dioxide molecule has more than one type of atoms.
(Example of an atom. Inner part, nucleon - consists of protons and neutrons. Outer part - electrons orbiting in electron shells)
Sources: Google Images
Friday, February 18, 2011
Quiz
Headline: Quiz.
We did a quiz today so as to check on our understanding on the topic, Atoms & Molecules.
I have learnt that when a question asks us about the number of subatomic particles in an atom of XXX, we should list out the number of protons, electrons and neutrons but not the total number of subatomic particles in it. For example, if a question asks us about the number of subatomic particles in an atom of boron with a nucleon number of 10, we should not answer that the number of subatomic particles in an atom is 15. Instead, we should answer that there are 5 protons, 5 electrons and 5 neutrons.
I have also learnt that atoms form ions as atoms react when they are forming compounds. They tend to lose or gain electrons so as to get the electronic configuration of a noble gas.
We did a quiz today so as to check on our understanding on the topic, Atoms & Molecules.
I have learnt that when a question asks us about the number of subatomic particles in an atom of XXX, we should list out the number of protons, electrons and neutrons but not the total number of subatomic particles in it. For example, if a question asks us about the number of subatomic particles in an atom of boron with a nucleon number of 10, we should not answer that the number of subatomic particles in an atom is 15. Instead, we should answer that there are 5 protons, 5 electrons and 5 neutrons.
I have also learnt that atoms form ions as atoms react when they are forming compounds. They tend to lose or gain electrons so as to get the electronic configuration of a noble gas.
(An example of a key in the periodic table)
Sources: Google Images
Wednesday, February 16, 2011
Worksheets
For today's Science lesson, we went through some worksheets and we were allowed to raise queries on the concepts which we did not understand.
3 Thoughts:
1) I have learnt that the similarities between an atom and an ion are that both of them have the same number of protons, neutrons and electron shells. As for the difference, an atom is neutral while an ion has a net charge (positive/negative).
2) I have also learnt that the difference between an oxygen atom and an oxygen molecule is that the oxygen atom has one atom but the oxygen molecule has several. As for their similarity, they both contain an oxygen atom.
3) I learnt that a mixture and a molecule of compound are different from one another. A mixture consists of different kinds of atoms mixed together. While a molecule of compound contains different kinds of atoms chemically combined together.
2 Questions:
1) Is it still considered a mixture when there is a presence of a mixture of atoms and molecules of element?
2) When the same kind of atoms mixed together, is it called a mixture or an element?
1 Useful application:
1) By clarifying all the misconceptions that we had, we are able to score better in our tests or examinations.
3 Thoughts:
1) I have learnt that the similarities between an atom and an ion are that both of them have the same number of protons, neutrons and electron shells. As for the difference, an atom is neutral while an ion has a net charge (positive/negative).
2) I have also learnt that the difference between an oxygen atom and an oxygen molecule is that the oxygen atom has one atom but the oxygen molecule has several. As for their similarity, they both contain an oxygen atom.
3) I learnt that a mixture and a molecule of compound are different from one another. A mixture consists of different kinds of atoms mixed together. While a molecule of compound contains different kinds of atoms chemically combined together.
2 Questions:
1) Is it still considered a mixture when there is a presence of a mixture of atoms and molecules of element?
2) When the same kind of atoms mixed together, is it called a mixture or an element?
1 Useful application:
1) By clarifying all the misconceptions that we had, we are able to score better in our tests or examinations.
Tuesday, February 15, 2011
More on Molecules
Today, we went through some worksheets and revised on the topic, Atoms and Molecules. Well, we focused more on molecules for this lesson.
I used to think that a molecule is an atom that stands by itself. But now I think that a molecule is actually made up of two or more atoms chemically combined together.
I also used to think that there is only one type of molecules. Now, I think that there are two types of molecules. One type is molecules of elements while the other type is molecules of compounds. Molecules of elements consist of a fixed number of same type of atoms chemically combined together. This type of molecules is called diatomic molecules. As for molecules of compounds, they are made up of a fixed number of different types of atoms chemically combined together.
There is also a chemical formula to represent a compound. The formula tells us about the types of atoms present in the compound and the ratio of different atoms found in the compound.
I used to think that a molecule is an atom that stands by itself. But now I think that a molecule is actually made up of two or more atoms chemically combined together.
I also used to think that there is only one type of molecules. Now, I think that there are two types of molecules. One type is molecules of elements while the other type is molecules of compounds. Molecules of elements consist of a fixed number of same type of atoms chemically combined together. This type of molecules is called diatomic molecules. As for molecules of compounds, they are made up of a fixed number of different types of atoms chemically combined together.
There is also a chemical formula to represent a compound. The formula tells us about the types of atoms present in the compound and the ratio of different atoms found in the compound.
(Top - Molecules of Elements. Bottom - Molecules of Compounds)
Sources: Google Images
Friday, February 11, 2011
First Class Test
Headline: First Class Test.
Today, we had our first class test and it is on the topic, Particulate Model of Matter.
I have learnt that when an element has good electrical conductivity and has the highest melting point, it will have the strongest forces of attraction between its particles. This is because the heat supplied will have a hard time overcoming the forces of attraction between the particles and therefore, having the highest melting point. However, does the density of the element affect the forces of attraction between the particles?
I have also learnt that when an iron nail is dropped into a glass of water, it sinks to the bottom of the glass. This is because an iron nail is a solid in which their particles are arranged in a fixed, regular pattern and are packed very closely together. But the particles of water are arranged in a disorderly pattern. Thus, the iron nail of a fixed mass and a smaller volume has a higher density than water.
Today, we had our first class test and it is on the topic, Particulate Model of Matter.
I have learnt that when an element has good electrical conductivity and has the highest melting point, it will have the strongest forces of attraction between its particles. This is because the heat supplied will have a hard time overcoming the forces of attraction between the particles and therefore, having the highest melting point. However, does the density of the element affect the forces of attraction between the particles?
I have also learnt that when an iron nail is dropped into a glass of water, it sinks to the bottom of the glass. This is because an iron nail is a solid in which their particles are arranged in a fixed, regular pattern and are packed very closely together. But the particles of water are arranged in a disorderly pattern. Thus, the iron nail of a fixed mass and a smaller volume has a higher density than water.
Thursday, February 10, 2011
Ions
Today, we learnt about ions and how they are formed.
3 Thoughts:
1) An ion is formed when an atom loses of gains electrons. Hence, in an ion, there is an imbalance in the number of protons and electrons.
2) A neutral atom can gain or lose electrons through chemical reaction. When an atom loses electrons, it will be positively charged, also known as cations. When an atom gains electrons, it will be negatively charged, called anions. Elements in the same group of periodic table will form ions of the same charge.
3) Atoms of metals tend to lose electrons while atoms of non-metals tend to gain electrons. Atoms form ions so as to achieve a noble gas (duplet or octet) structure.
2 Questions:
1) Will an atom lose or gain too much electrons?
2) Will there be a case where atoms of metals gain electrons?
1 Useful application:
1) When we know more about ions, we will be able to know what chemical changes/properties the elements are undergoing/have.
3 Thoughts:
1) An ion is formed when an atom loses of gains electrons. Hence, in an ion, there is an imbalance in the number of protons and electrons.
2) A neutral atom can gain or lose electrons through chemical reaction. When an atom loses electrons, it will be positively charged, also known as cations. When an atom gains electrons, it will be negatively charged, called anions. Elements in the same group of periodic table will form ions of the same charge.
3) Atoms of metals tend to lose electrons while atoms of non-metals tend to gain electrons. Atoms form ions so as to achieve a noble gas (duplet or octet) structure.
2 Questions:
1) Will an atom lose or gain too much electrons?
2) Will there be a case where atoms of metals gain electrons?
1 Useful application:
1) When we know more about ions, we will be able to know what chemical changes/properties the elements are undergoing/have.
(Example of how atoms lose or gain electrons)
Sources: Google Images
Tuesday, February 1, 2011
Atoms and Molecules
For today's Science lesson, we went through the concepts on atoms and molecules which we had learnt last year. Then, we went deeper into the topic and gained many new concepts.
3 Thoughts:
1) Atoms contain electrons which they move around the nucleus in regions called electron shells. The more the electrons, the more electron shells an atom has. In addition, only a certain number of electrons move in each of the electron shells. For example, the first shell which is nearest to the nucleus can only hold a maximum of 2 electrons. While the second and third electron shells can each holds a maximum of 8 electrons.
2) The arrangement of the electrons, also known as electronic configuration or electronic structure, is very important as it determines the chemical properties of the atom and we are able to know what changes the element will go through.
3) We had also learnt how to draw electronic structures by using cross or dot to represent each electron. The cross or dot must always be placed opposite each other, like East to West or North to South.
2 Questions:
1) Do all the electrons in the electron shells move in the same way (e.g. clockwise direction)?
2) Why is it only that the inner most of the electron shells can only hold 2 electrons?
1 Useful application:
1) By knowing the arrangement of the electrons in an atom, we are able to know the way how elements are placed in the periodic table.
3 Thoughts:
1) Atoms contain electrons which they move around the nucleus in regions called electron shells. The more the electrons, the more electron shells an atom has. In addition, only a certain number of electrons move in each of the electron shells. For example, the first shell which is nearest to the nucleus can only hold a maximum of 2 electrons. While the second and third electron shells can each holds a maximum of 8 electrons.
2) The arrangement of the electrons, also known as electronic configuration or electronic structure, is very important as it determines the chemical properties of the atom and we are able to know what changes the element will go through.
3) We had also learnt how to draw electronic structures by using cross or dot to represent each electron. The cross or dot must always be placed opposite each other, like East to West or North to South.
2 Questions:
1) Do all the electrons in the electron shells move in the same way (e.g. clockwise direction)?
2) Why is it only that the inner most of the electron shells can only hold 2 electrons?
1 Useful application:
1) By knowing the arrangement of the electrons in an atom, we are able to know the way how elements are placed in the periodic table.
(Example of an electronic structure of an atom)
Sources: Google Images
Friday, January 28, 2011
Group Work! :D
Headline: Discussing topics on our research-base-project.
Today, we gathered in our small group to discuss about the project that we will be working on. We discussed about the various possibilities and topics that we can do research on. Each of us in the group had to share ideas between one another. Then, we decided that we should all collect newspaper articles when we get home so that we are able to plant new and better ideas from there.
Well, from today's lesson, I had learnt that teamwork and cooperation within the group have to be maintained so that the quality of our work will be better and most importantly, we will HAVE FUN throughout this whole experience!
Today, we gathered in our small group to discuss about the project that we will be working on. We discussed about the various possibilities and topics that we can do research on. Each of us in the group had to share ideas between one another. Then, we decided that we should all collect newspaper articles when we get home so that we are able to plant new and better ideas from there.
Well, from today's lesson, I had learnt that teamwork and cooperation within the group have to be maintained so that the quality of our work will be better and most importantly, we will HAVE FUN throughout this whole experience!
Sources: Google Images
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