Physical Properties of Ionic and Covalent Compounds

After learning about the dot-and-cross diagrams of ionic and covalent compounds, we're going to learn about their physical properties.

Here're the instructions:

PART A

1) Click on the image below to download and run the flash software.

Click to Run

2) Drag the conductivity tester into the beaker of water. Place the negative and positive electrodes into the water, but not touching the bottom of the beaker.

3) Click on the salt shaker and drag it to shake. Does salt dissolve? Does it conduct electricity? Why do you think the solution can/cannot conduct electricity? Record your observations and thoughts in the given table.

4) Repeat the experiment with the sugar shaker.

PART B

1) Click on the 'Micro' tab at the top left hand corner.

2) Shake salt into water. Before the salt lands on the water, pause the animation. What do you think will happen to the salt particles?

3) Resume the animation. Are your predictions right?

4) Repeat the experiment for sugar.

5) Click on the 'Water' tab at the top left hand corner to confirm your predictions.

PART C

1) Watch the video on the heating of salt below. How do you think the colour and state of salt would change over time? Why? Record your observations in the given table.

2) Repeat the experiment for sugar. Discuss your observations and try to think of a suitable reason for it with your friend.

CONCLUSION

By now, you should be familiar with the electrical conductivity and melting points of ionic and covalent compounds.

Read More

Air And The Environment

Read More

Tired of Being 'Happy','Sad', 'Afraid', 'Shy', 'Nervous' and 'Frustrated'? Why Not Try These Words?

Are you sick of using the same few words to describe the richness of your thoughts and feelings? Do you wonder about the different shades of happiness you feel? The joy of passing a test is different from the joy of finally understanding Ohm's law, and this joy is in turn different from the joy of encouraging someone to smile.

Instead of feeling happy, why not be thrilled when you get to visit Resorts World Sentosa? Or be radiant as you thank your parents for their care?

Why be frustrated when you can be exasperated, miffed or ruffled up? 

Do be aware of the subtle differences in meaning the words have. For example, while both morbid and crestfallen describe sadness, they describe different kinds of sadness. Morbid suggests an obsession with death while crestfallen refers to suffering from a thorough disappointment. 

Have fun using these words in your next conversation! 

Read More

3N: The Mole Concept

What is a mole?

To a biologist, a mole is an animal:

To a plastic surgeon, a mole is a bodily imperfection:

But to a chemist, a mole is a unit of measurement.

SI unit: mole
Symbol: mol
Definition: Amount of substance containing 6 x 10²³ particles

Why do we need this mole concept?

The mole concept enables us to calculate the amount of chemicals needed to make our clothing, food, drinks, toothpaste, medicine, printer inks and almost everything that has been manufactured.

What are the ways to measure a substance's mass?

There are three ways:

Relative atomic mass (A_r): 

• average mass of 1 atom compared to 1/12 of the mass of carbon-12 atom
• find directly from the Periodic Table
• no units

Relative molecular mass (M_r):

• average mass of 1 molecule compared to 1/12 of the mass of carbon-12 atom
• need to know chemical formula first, then sum up the A_r of all the atoms present in the compound
• no units

molar mass:

• mass of 1 mole of substance
• equivalent to A_r and M_r, but with units
• units: g/mol

What is the formula you need to know?

Have fun with the numbers!

Read More

Why Study Chemistry?

Have you ever wondered what makes up the food that you have been putting into your mouth? Or how your latest handphone works? Chemistry is the fascinating study of what we eat, how we live and why certain chemicals come together in strange and wonderful ways.

Here are more reasons why you should elect to study this scientific field:

1) Because our schools don't offer Potions classes and the closest alternative is Chemistry.

In the labs, you get to mix, heat, burn, boil, cool, freeze, test and purify all kinds of interesting materials. There will be colour changes, from pale sky-blue to deep coral purple. There will be smoke, fires (while observing your personal safety at all times!) and pungent gases.

2) You'd finally discover what chemicals (or drugs) you've been eating all along.

The next time you walk into a supermarket, you can pick up an orange and tell your friends, "there's citric acid in this fruit." To top it off, you can even list all the properties of an acid! Everyone will be so impressed by the extent of your knowledge that they yearn to be your best buddies. 

3) You'd be able to understand lame science jokes.

Suddenly, all the strange comments that your teachers have been saying, well, suddenly, they all make PERFECT SENSE.

4) Or even make come up with even lamer ones yourself:

5) The world becomes more friendly when you understand the scientific ways in which it functions. 

Science equips you with the knowledge and perspectives to understand the people, places and phenomenon around you in wondrous new ways. 

6) You might get the chance to tinker with expensive gadgets that will produce beautiful images.

This catalyst is like a rose with thorns.

7) You don't really want to study other subjects. So, might as well study Chemistry, right?

Now, pay attention in class.

8) At times, you may even get to see equivalents of shooting stars.

Images credit: Angelo State University

8) Most importantly, you learn to defend yourself from cheats, hacks, charlatans, scammers and liars. They may tell you that certain stones can cure cancers, offer good luck and grant excellent grades, if only you'd pay them. DO NOT TRUST THEIR LIES.

 

Learning should be great fun. It should be awesome and exciting. This is all the more so for the study of Chemistry. There are so many reasons why we should enjoy this scientific adventure.

All the best on this journey towards understanding and appreciating the laws underlying this world that all of us live on.  

Read More

Ask yourself: why are you studying?

Listen to the Mustn'ts, child, listen to the Don'ts.
Listen to the Shouldn'ts, the Impossibles, the Won'ts.
Listen to the Never Haves, then listen close to me.
         Anything can happen, child, Anything can be.

- Shel Silverstein

Do you ever wonder why you’re studying and for whom? Is it to make your parents happy? Or to stop your teachers from nagging?

Is it to keep up with your friends? Or do you fear not doing well and being deemed as an ignorant fool?

Maybe it’s because you don’t know what else to do with your precious time, energy and resources? Or is it precisely because you know what you want to do that you’re putting in so much effort?

The truth is, there may be many reasons why you need/want to study. Some of these reasons are dependent on the people around you. While it’s good to put in effort because you care for others and how they think, it’s even better to study because you wish to satisfy your own curiosity.

Ultimately, why you study depends on yourself and the fruits you harvest belong to you too. By learning and questioning what you learn, you allow yourself to strengthen and grow, like a tender sapling nourished by droplets of ideas and information.

Be excited about your learning and your excitement will bring you a magical joy.

Read More

All the best this week :]

Here're some quotes to keep you going as a new week brings fresh hopes, challenges and fulfillments!

Remember that you've the spark of greatness within. Also, remember that you must nurse this spark into a ball of energy and lightning such that you may and would build a better future for everyone!

Read More