The periodic table was not created by one scientist. It is a collaboration of decades upon decades of work and is organized for a very specific set of reasons. It's important to note before we discuss how the table is organized, that not only COULD it be organized differently than it is today, but many scientists actually WANTED it organized differently.
Fist and foremost, the elements on the table are placed in order of their "atomic number" (how many protons the atom has) from lowest to highest. But that is not all, because if it were simply organized that way, the table would be a straight line.
In the table, the elements are arranged into "groups" and "periods". A horizontal row of elements across the table is a period. Each period stands for a ring of electrons. The further left to right you go in a period is how full that ring of electrons is in that atom. The further right you go, the more that atom likes to keep its own electrons.
A column of elements is a group. Elements in a group have similar arrangements of electrons, making them have similar chemical properties. For example, the group to the far right is the noble gases, which almost never bond with other atoms and they are all gases at room temperature.
Wednesday, May 15, 2013
Standard 28: Accurately compares and contrasts the properties and behaviors of magnetism and electricity
It's all about electrons.
Electricity and magnetism, while different processes, are inseparable. Their similarities are almost too many to count. First, they both subscribe to the law of "opposites attract, like repel". Electricity has positives and negatives just like magnetism, although in magnetism they're called north and south. Another similarity is that distance matters for both of them. The push or pull of the positives and negatives is going to be stronger depending on how close the two bodies are. Their interaction with metal is comparable, and both have the ability to transfer their attractions to metals.
Some of their differences are that first, magnetism has a physical push or pull that we can observe with our own muscles. Electricity is only observable through completed circuits. Electricity is also easy to transfer into thermal energy, while magnets will generally not heat things up.
Electricity and magnetism, while different processes, are inseparable. Their similarities are almost too many to count. First, they both subscribe to the law of "opposites attract, like repel". Electricity has positives and negatives just like magnetism, although in magnetism they're called north and south. Another similarity is that distance matters for both of them. The push or pull of the positives and negatives is going to be stronger depending on how close the two bodies are. Their interaction with metal is comparable, and both have the ability to transfer their attractions to metals.
Some of their differences are that first, magnetism has a physical push or pull that we can observe with our own muscles. Electricity is only observable through completed circuits. Electricity is also easy to transfer into thermal energy, while magnets will generally not heat things up.
Standard 21: Uses concepts of energy, work, and force to analyze systems such as simple and complex machines
The first concept to understand about how simple machines work is the formula work = force x distance . What this means is that if I need to get a certain amount of work done, but I have a limitation on how much force I can apply, I can make up for this discrepancy by increasing the distance I do. Simple machines let us do exactly that. The let us trade distance for force or force for distance.
Picture a box that weights 200 pounds. Let's say I need to lift this box onto a platform that is 4 feet high. Now, being the skinny little kid that I am, there's no way I can accomplish this goal by just lifting it straight up. But, by introducing a ramp (an inclined plane) I can cheat the system. If I put in a long ramp that leads from the ground to the platform at an angle, I will increase the distance I have to go, say from 4 feet to 20 feet. But, because work = force x distance , I have just decreased the force I need to apply by the same ratio as distance added. Work smart, not hard, thanks to simple machines.
Picture a box that weights 200 pounds. Let's say I need to lift this box onto a platform that is 4 feet high. Now, being the skinny little kid that I am, there's no way I can accomplish this goal by just lifting it straight up. But, by introducing a ramp (an inclined plane) I can cheat the system. If I put in a long ramp that leads from the ground to the platform at an angle, I will increase the distance I have to go, say from 4 feet to 20 feet. But, because work = force x distance , I have just decreased the force I need to apply by the same ratio as distance added. Work smart, not hard, thanks to simple machines.
Standard 15: Articulates similarities and differences among the properties of solutions, mixtures, and compounds
The one thing solutions, mixtures, and compounds all have in common is that they are a combination of different elements on the periodic table. They are all made up of more than one type of atom. But what are the differences?
A compound is the result of two or more elements that have been chemically bonded. Things like H20 (water) or C3H8 (propane). They are bonded either covalently (sharing electrons such as water) or ionically (positive and negative charged atoms coming together such as NaCl).
A mixture is when you mix two or more substances, but you do not chemically bond them. This can be anything from salt and sand mixed together to mixing cocaine and non-dairy creamer. You know...if you're into that kind of thing. The important thing is that, at least on a small scale, the different substances are still distinguishable.
A solution is the result of when you dissolve a substance into a liquid. Dissolving happens when the solute (such as salt, NaCl) has its atoms separated by the solvent (such as water). The positively-charged hydrogen atoms in water pull on the chlorine atoms while the negatively-charged oxygen pulls on the sodium, breaking the ionic bond of salt, and dissolving the salt into the water.
A compound is the result of two or more elements that have been chemically bonded. Things like H20 (water) or C3H8 (propane). They are bonded either covalently (sharing electrons such as water) or ionically (positive and negative charged atoms coming together such as NaCl).
A mixture is when you mix two or more substances, but you do not chemically bond them. This can be anything from salt and sand mixed together to mixing cocaine and non-dairy creamer. You know...if you're into that kind of thing. The important thing is that, at least on a small scale, the different substances are still distinguishable.
A solution is the result of when you dissolve a substance into a liquid. Dissolving happens when the solute (such as salt, NaCl) has its atoms separated by the solvent (such as water). The positively-charged hydrogen atoms in water pull on the chlorine atoms while the negatively-charged oxygen pulls on the sodium, breaking the ionic bond of salt, and dissolving the salt into the water.
Standard 13: Articulates evidence for and implications of the laws of conservation of mass and energy
"Conservation of mass" means that the particles in any particular object cannot be destroyed and they cannot increase sporadically. They can only be moved around or changed into different particles. The law of conservation of mass says that when two things become one thing, or one thing becomes two things, the mass of the original(s) is equivalent to the mass of the new thing. For example, if you have hydrogen atoms and oxygen atoms, and you combine them to make water molecules, there has been no mass lost or gained and there can never be. And even if that water changes from a liquid to a gas or a solid, the mass still remains the same.
Energy is no different. The "conservation of energy" means that the total amount of energy in a system cannot increase or decrease, it can only change forms. Potential energy can become kinetic energy, and kinetic can become thermal energy due to friction, but the energy is not created or destroyed.
Energy is no different. The "conservation of energy" means that the total amount of energy in a system cannot increase or decrease, it can only change forms. Potential energy can become kinetic energy, and kinetic can become thermal energy due to friction, but the energy is not created or destroyed.
Standard 3: Understands the interrelationships of basic and applied sciences, and technology
The differences between applied science and basic science are often exaggerated. The myth is that applied science helps out with "real world problems" and the development of technology, while basic science is done for little more than for the thrill of scientists with big research grants. In reality, these concepts are crucially intertwined.
Science helps us understand. Technology helps us accomplish.
Applied science examines a specific set of circumstances with the end goal of development of technology to accomplish a task. Clinical drug trials, software development, and agriculture experiments are all examples of applied science with specific goals in mind.
Basic science focuses on scientific theories and fundamental principles. The goal of basic science is to gain insight into how something in the universe works. Projects of basic science do not have a specific goal in mind or problem to solve Space exploration, for example was perused without any real goal in mind, unless you count looking more badass than the Russians as a goal.
The myth is that basic science has no practical applications. But history is full of example of "research for research's sake" leading to real world applications. There's no way to know what discoveries in basic science will lead to vast advances. The discovery of x-rays had no practical purpose, until we realized they could be used to see through human bodies. Materials developed for space exploration are now used in cancer treatments. Penicillin's discovery was a complete accident. We don't know what research is going to be helpful to the human race until we do it.
Standard 2: Understands the value and limitations of scientific models
As Albert Einstein said: "If you cannot explain it simply, you do not understand it well enough."
Scientific models provide ways to read and understand a complicated scientific concept, law, or theory by breaking it down into a simpler form. By breaking down a complicated concept visually, scientists can communicate their ideas in a way that is easier for non-experts to understand. Plus, it gives the scientists a shortcut so they can lump similar concepts together.
Modelling is an essential part of all scientific activity, especially when it comes to educating lay people about discoveries. It would be nearly impossible to teach people about things like the water cycle or construction of molecules without being to look at them visually.
But, there is a downside. First of all, it is nearly impossible to be completely accurate with visual representations. Shortcuts have to be made. Since there's only so much that can be drawn on paper and seen with the eye, we run the risk of oversimplification and making people think that the concepts look literally like they do on the model. Models are important, but they cannot be the only thing used by scientists when developing theories.
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