Friday, June 09, 2006

Phases of Matter

I’m sure you’re already familiar with the 3 phases (states) of matter so I’ll just summarize them.

1. Solid

  • has a definite shape
  • has a definite volume
  • very difficult to compress
  • particles packed close together and held rigid

2. Liquid*

  • follows the shape of its container
  • has a definite volume
  • difficult to compress
  • particles are close together but are free to move

3. Gas*

  • has no definite shape
  • has no definite volume; fills its container
  • easy to compress
  • particles are far apart

    *Liquid and Gas are considered fluids because of their ability to flow.

    You may have heard of the fourth state of matter- plasma. Written below are two definitions. They have the same meaning but the second one is more concise:

    - Plasma is a hot gas in which atoms are partially broken down to form charged particles or ions.
    - Plasma is a gas that is partially or completely ionized.
    There are several factors which determine the state of matter. They are:

    1. The nature of the particles of matter
    2. Types of chemical bonds present in the matter (we'll tackle chemical bonds later on)
    3. Temperature
    4. Pressure
    Matter is capable of changing from one phase to another. Most of the time, this happens because of a change in temperature. Here are the 4 phase changes of matter:

    1. Solidification
    - Liquid to solid
    - Happens when there is a decrease in temperature causing particles of liquid to lose kinetic energy, move closer together, and may eventually solidify.
    - Ex. Water freezes into ice

    2. Melting
    - Solid to Liquid
    - Happens when there is an increase in temperature causing the kinetic energy of solid particles to increase. If enough energy is absorbed by the solid, its particles will break away from nearby particles and posses liquid properties.
    - Ex. Ice melts into water

    3. Vaporization
    - Liquid to gas
    - Occurs when there is an increase in temperature causing the kinetic energy of liquid particles to increase. If enough energy is absorbed by liquid, its particles will break away from nearby particles and become gas.
    - Ex. Boiling water until it vaporizes

    4. Sublimation
    - Solid to gas
    - Happens when solid changes to gas without passing the liquid state
    - Ex. Mothballs & Dry ice

Thursday, June 08, 2006

Properties of Matter

There are two properties of matter namely, physical & chemical properties. Physical property is something you can observe without changing the composition of matter. For example, you saw a jar and you said, “That jar is smooth, shiny, and 10 inches in diameter”. Smooth, shiny, and 10 inches are all physical properties of the jar. Physical property can further be divided into two: extrinsic & intrinsic properties. Extrinsic property describes the outside appearance of objects. Smooth & shiny are extrinsic properties of the jar, while 10 inches is the intrinsic property because it describes the measurable aspects of an object.

Physical changes are changes that alter a substance with out changing its composition. An example is melting & solidification. We all know that ice is solidified water. When ice melts, voila! You still have water! Another example tearing a piece of paper; even if you tear the paper into a million tiny pieces, those tiny pieces is still (yep, that’s right!) paper! Boiling water is also a physical change.

Chemical property can be observed when there is a change in the composition of matter (chemical change). An example is burning. When we burn wood, both physical and chemical changes occur. First, you may see the color, shape, & size changing, and then eventually the wood becomes ashes. Rusting & cooking are also examples of chemical changes.
Here are some signs of chemical change:
- formation of gas
- formation of precipitate (insoluble substance)
- liberation or absorption of heat
- distinct change in color
- production of flame
- presence of bubbles

Sometimes, physical & chemical changes are accompanied by endothermic or exothermic reactions. In an endothermic reaction, heat is absorbed by the substance; while in an exothermic reaction, heat is released by the substance to the environment. An example of endothermic reaction is photosynthesis. Plants absorb the heat of the sun in order to make food. Using this example, we can say that in an endothermic reaction, the reactants have lower energy contents than the products (there is an increase in the temperature of the substance). On the other hand, the solidification of water into ice is an exothermic reaction. The reactants have higher energy contents than the products (there is a decrease in the temperature of the substance).

Wednesday, June 07, 2006

Homogeneous and Heterogeneous Systems

We are about to discuss homogeneous and heterogeneous systems, but first, what is a system? In chemistry, a system is any group of atoms, molecules, ions, & substances. A system can either be homogeneous or heterogeneous. In a homogeneous system, substances are combined such that the components are not easily distinguished by the naked eye. Alcohol solution and sea water are examples of this type of system. To us, sea water is nothing but water. However, it is composed of many minerals, which we cannot see.

In a heterogeneous system, substances are combined such that their components are easily distinguished and their distribution is not constant. An example is a mixture of marbles and beads. In the mixture, you can easily tell apart the marbles from the beads. A terrarium is also a heterogeneous system.

Can you think of other examples of a homogeneous and heterogeneous system?

Wednesday, December 14, 2005

6 Main Branches of Chemistry

Since chemistry is a very broad topic to study, people (most probably scientists) divided this into different branches. Here are the 6 main branches of chem..

1. Analytical chemistry- concerned with the separation, identification, and composition of materials.

Qualitative analysis vs. Quantitative analysis

Qualitative analysis involves our senses. If we say that a piece of paper is blue in color that is a qualitative analysis. Quantitative analysis on the other hand involves measurement. If we say that a solution is 30 % water that is a quantitative analysis.

2. Physical chemistry- involves the study of the physical characteristics of materials and the mechanisms of their reactions.

3. Organic chemistry - study of substances containing carbon.
- the chemistry of carbon compounds

4. Inorganic chemistry- study of other substances not containing carbon
- the chemistry of materials other than those classified as organic.

5. Biochemistry- the chemistry involving living things
- the study of materials and processes that occur in living things

6. Nuclear chemistry- involves the study of subatomic particles and nuclear reactions

The Scientific Method

Scientists have a logical way of solving problems. They call this the scientific method. It is a step by step process, which leads to the solutions of problems. I know you’ve been studying this since elementary, so I’ll just enumerate the process.

1. Identify the problem- how can you solve something if you don’t know what your problem is?

2. Formulate a hypothesis- this is a scientific guess, which serves as your temporary answer to the problem

3. Test the hypothesis- in other words, do the experiment!

4. Analyze the data- what was the result of your experiment? Was your hypothesis right?

5. Formulate a conclusion/ generalization- the generalization is often the answer to the objective of an experiment.

Tuesday, December 13, 2005

What is Chemistry?

Here are several definitions of the word Chemistry. I’ve got them from different sources, but they all mean the same thing. Try formulating your own definition of chemistry. After all, your teacher wouldn’t just want you to copy the meaning. They want you to understand it.

- Chemistry is a physical science. (what is physical science? Go check it out in the encyclopedia! =D )
- Chemistry is the study of matter, their composition, structure, properties, and the changes they undergo.
- Chemistry is the science of materials, their composition and structure, and the changes they undergo.
- Chemistry is the study of chemicals.

Ok. So what is chemistry?

One definition says it’s the study of matter. Do you still remember what matter is? Well, if you’ve forgotten it, I’m sure you’ll never forget it again once you’ve studied Chem.

Matter is anything that occupies space and has mass and weight.

This means that you’re matter as well as all the things around you.

Chemistry studies everything about matter (including the most elementary particles that make it up!). Can you imagine how broad that is? That’s the reason why this subject is divided into different systems, or commonly called branches (which will be discussed later on).

Chemistry came from the Greek word “chemeia” which means alchemy. Alchemy is often called the art of metal working. The early alchemists’ goal was to seek for the “elixir of life” or better known as the Philosopher’s stone (yep! Just like the one in Harry Potter!). It was believed that this stone can make man immortal. This is the reason why alchemy was called the “black art” or “black magic”. The practice of alchemy was the beginnings of chemistry.

However, unlike alchemy, which is fraught with magic and superstition, chemistry slowly evolved into a form of science. It is based on facts gained from observation and experiments. Chemistry is also called a “servant science” because it is being used in different fields of study like biology, physics, earth science, and lots more!

This subject may sound very hard. But believe me, it’s also very interesting! It’s fun learning Chemistry! And remember:

“If you think this subject is difficult, it will be difficult. But if you think it’s fun and easy, then it will definitely be so!”

Wednesday, December 07, 2005

Welcome to Basic Chemistry!

This blog was created for people who would like to get some information about chem. If you're a third year high school student or anyone who just likes to read about chem, you might find my blog useful. Right now, I'm still making my modules to post in this blog. I'll start posting around late December or early January.

Basic Chemistry covers topics like states of matter, molecules, the atom, the periodic table, moles, chemical reactions, gas laws, balancing equations, and lots more!

So visit my blog again in a few weeks time, ok?

Until then, bye! =)