Tuesday, July 13, 2010

IONS & CHEMICAL BONDING

IONS are atoms with either extra electrons or missing electrons. A normal atom is called a neutral atom. That term describes an atom with a number of electrons equal to the atomic number.

IONS have either a positive or negative charge, depending on whether they have more electrons than protons or less. Since they are no longer neutral, they cannot be called atoms anymore.

IONS are created when atoms try to gain or lose electrons to achieve stability. Stability refers to having the maximum number of electrons in their outermost shell.

Elements bond when they become ions, by 'exchanging' or 'sharing' electrons.
e.g.1: Sodium Chloride (NaCl)
Sodium needs to lose one electron in order to achieve stability, while chlorine needs to gain one electron. Sodium then gives its unwanted electron to chlorine so that they both can achieve stability. This bond is between a metal element and a non-metal element, therefore it is an ionic bond.
e.g.2: Hydrogen (H2)
Each hydrogen atom has one electron, but it needs two to fill up its shell. So, two hydrogen atoms can bond by sharing their one electron with each other, allowing both to become stable. this is known as a covalent bond, as it is between two non-metals.

http://www.chem4kids.com/files/atom_ions.html

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ISOTOPES

An ISOTOPE is an atom that has missing neutrons or extras neutrons. An atom is still the same element if it is missing a neutron. They are just a little different from every other atom of the same element.

Take carbon for example:
There are a lot of carbon atoms in the universe. The normal ones are carbon-12. These atoms have 6 neutrons. There are a few straggler atoms that don't have 6. Those odd ones may have 7 or even 8 neutrons. As you learn more chemistry, you will probably hear about carbon-14. Carbon-14 actually has 8 neutrons (2 extra). C-14 is considered an isotope of the element carbon.

http://www.chem4kids.com/files/atom_isotopes.html

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Friday, July 9, 2010

ATOMS & MOLECULES

ATOMS are the basic building blocks of everything you can see around you, and even lots of things you can't see, like the air that you breathe. Atoms are so small that there are millions and billions and trillions in the tiniest speck you can see. Solids, liquids, gases - all matter - are made up of atoms (or other things, like molecules, that are made from atoms)!

Elements are the kinds of atoms that we can have. Carbon is an element, hydrogen is an element, and so is oxygen. (We can call them by their names, or by their symbols - C for carbon, H for hydrogen, and O for oxygen.) All the elements are listed out in a periodic table. If it's in the table, it's an element!

Atoms can join together - they form bonds together - to make MOLECULES. For example, two atoms of hydrogen hook together to form a molecule of hydrogen, H₂ for short.

http://pslc.ws/macrog/kidsmac/atoms.htm

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Friday, March 26, 2010

Q: Can food be digested while you're upside-down?

The answer is: yeah.
Thanks to the muscles in the digestive system.

I have an awesome video here from possibly my favourite variety show ever. (by the way, it's korean so you have to read the subtitles) I put the whole episode here but its really in part 2.

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TOPIC 1: Digestion.

The digestive system is made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food.

Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine—also called the colon—rectum, and anus. Inside these hollow organs is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. The digestive tract also contains a layer of smooth muscle that helps break down food and move it along the tract.

When you eat foods—such as bread, meat, and vegetables—they are not in a form that the body can use as nourishment. Food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so the body can use them to build and nourish cells and to provide energy.

Digestion involves mixing food with digestive juices, moving it through the digestive tract, and breaking down large molecules of food into smaller molecules. Digestion begins in the mouth, when you chew and swallow, and is completed in the small intestine.

http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/

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Sunday, February 14, 2010

Dangers of Electricity

Electricity and Water If your hands tingle when you put them into the sink it may mean the water is conducting electricity and something is wrong. Let an adult know, as they may need to call an electrician. When you have a bath, there should be nothing electrical anywhere near you. In a bath, the metal plughole and the plumbing is connected to the earth, making it a conductor of electricity. This means if a household appliance such as a light or hair dryer fell into the bath, whoever was in it would also become a conductor of electricity. Wherever you are, if you get into trouble call out for help and make sure not to touch anything. Get whoever helps you to turn the electricity of

Water can conduct electricity because electrons can flow by hitching a ride on atoms and molecules in the water. Water contains dissolved substances, such as salt. These greatly increase the ability of water to conduct electricity. That's why electricity passes easily through our bodies - because our bodies contain water and salt. This is also why it's important to keep water away from electrical appliances.

Powerlines

If you fly a kite and it gets caught in the overhead powerlines, live electricity could travel down the string and seriously hurt you. So be careful. Never climb a tree that is near powerlines. After a storm if you see some fallen powerlines, stay well clear of them. There is a strong chance they are still "alive".
We all like to play outside, but there are electrical hazards that we need to know about. Electricity poles and wires are all around us. They can be above us, next to us, and even below us. Whenever you can, play in open spaces away from electricity poles, towers and powerlines.

Metal

Never put a metal object - like a knife - into a toaster. It is very dangerous! Never put anything in a power point that's not meant for it, especially if the thing is metal. Electricity will travel right up the metal object into your body. Be careful when climbing a ladder at home. The power lines connected to our house are usually protected, but they can be damaged by rubbing against the gutter or a tree, or through exposure to the sun. If a person is on a metal ladder and touches the exposed line, the electricity will travel through their body to the earth.

We all come into contact with metal objects on a daily basis - turning on a tap, using our computers and even opening the fridge. Because metal conducts electricity, you have to be very careful when you use metal items.

Dangerous Situations

Faulty appliances and damaged electrical leads should be disconnected at the power point and fixed or replaced by an electrician. Never stack power points. Use a power board or have an extra power point installed. Stacked power points can cause fires.

Always be on the look out for dangers in and around your home. This could be anything from a faulty electrical lead to a "stacked" power point - one with too many plugs in it. These situations could be life threatening and an electrician should be called in to fix them.

http://www.childsafetyaustralia.com.au/children/electricity/electricity.htm

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Friday, February 12, 2010

Power is the rate at which work is performed or energy is converted. It is an energy per unit of time. As a rate of change of work done or the energy of a subsystem, power is

where P is power, W is work and t is time.

The SI unit of power is the watt (W), which is equal to one joule per second.

http://en.wikipedia.org/wiki/Power_%28physics%29

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