By: Chloe McLennan
Crystal Formation: Day One
Initial Research – Thursday 12th
What is a crystal?
A crystal is a build-up of chemical compounds that connect together in a steady arrangement letting light reflect off it. These substances form a solid material which can be tiny or quite large.
What Substance can be used to make crystals?
What are some examples of crystals in nature? What household
items can you also grow crystals from?
Household items you could use:
Explain the process of crystal growth?
Sodium and Chlorine atoms both share apair of electrons in an ionic bond. While in solution, the Sodium and Chlorine are separated by water molecules. As the water evaporates from the solution, the Sodium and Chlorine atoms begin to bond together, first as single molecules and then the molecules bond together, forming crystals. Every molecule will form the same shape crystal each time it forms. The crystal shape for salt is a cube like a six-sided die.
Explain how crystals can grow in different shapes and sizes?
Crystal can come in other shapes than just cubes. For example, you can see triangle
shapes in crystals like rubies and amethysts. The unit cells for these crystals are more difficult than in salt and they have a different shape, but the unit cells still stack together in a regular pattern to make a crystal. Perfect crystals have only straight edges, but most of the crystals we see in nature aren't perfect. They often grow in confined spaces in the ground and don't have the room to grow in even directions. So they may have some straight edges, but look rounded or jagged in other places.
Outline a few types of crystals?
Diamonds, rubies, sapphires, and emeralds have been a popular type of crystal for thousands of years. They are highly valued due to their beauty and relative small amounts that exist in nature. There also opals which is an Australian crystal, not so rare in the outback. Plenty are gathered each week. Salt is used in day to day cooking and cleaning. Sugar is used in cooking also.
What effect do crystals have on light travelling through them? (Relate to reflection, refraction, dispersion and diffraction)
Light behaves differently depending on which direction the light is reflecting at the crystal. The index of refraction depends on both composition and crystal structure. When light hits a crystal at a certain point, there will be a reflection of bright light. In some circumstances the light can be quite blinding, but it depends on the crystal.
What are the optimum conditions for crystal growth?
Warmth is the key to forming crystals. A jar's surroundings should be warm also for optimum crystal growth. Warm air temperature helps water evaporation, causing the crystals to grow more quickly. Crystals will still grow in cooler temperatures, but it will take much longer for the water to evaporate. Crystal growth also requires light. Again, the crystals will eventually grow in the dark, but it will take a very long time. Light evaporates water as heat does; if you put a jar of what you are using to make your crystal you should have crystals forming in a minimum of a few days
· 25 grams of potash alum
· 2x 250 ml beaker
· 170 ml of hot water
· stirring rod
· filter funnel
· filter paper
· watch glass/more filter paper
1. Place approximately 25 g of potash alum in a 250ml beaker
2. Add 170ml of hot water
3. Stir the mixture until the crystals have dissolved, the solution may be slightly cloudy which is perfectly fine.
4. Filter the warm solution through a filter funnel (with the filter paper inserted) into the second clean beaker.
5. Cover the beaker of solution with the watch glass or fresh filter paper and set aside in a cool sheltered place and allow it to stand undisturbed overnight.
6. The first beaker and funnel can be cleaned and dried and the waste and filter paper can be thrown out.
· 2x 250ml beaker
· stirring rod
· plastic spoon
· left over potash alum
· smart phone/camera
· log book/diary
· loose fitting paper hat
1. Observe the beaker containing the solution. The bottom should be covered with a small layer of crystal because the solution is cold.
2. Gently decant (pour off) the clear liquid above the crystals into the clean beaker and set aside. Make sure the crystals are left in the other beaker. If no crystals have formed overnight, you can seed the solution. Do this by adding crystals from the original alum and let it sit overnight again. You may also need to stir the solution with your stirring rod.
3. Choose one good symmetrical crystal or group of crystals to act as the ‘seed’ for your large crystal. Using your plastic spoon, tweezers, tongs or spatula transfer the chosen crystal into the middle of the beaker with decanted solution.
4. NOTE: If you want the crystal to grow rapidly suspend the crystal with a nylon thread tied to a pencil resting on the rim of the beaker.
5. Take a picture of the crystal in line with the ruler so you measure its size and mark the level of liquid in the beaker.
6. Record this in your logbook.
7. Cover the solution with a loose fitting paper hat that allows water to slowly evaporate and keep out foreign particles. Keep it somewhere where the temperature will stay constant.
· 2x 250ml beakers
· smart phone
· log book
1. Once a week record the level of liquid in the beaker and without moving the crystal take a photograph of it next to the ruler.
2. Estimate and record how much the crystal has grown.
NOTE: Try to avoid disturbing the crystal as much as possible. Don’t touch the crystal with your fingers!
3. If any isolated crystals appear you can remove them gently with tweezers. If small crystals begin to form on your main crystal dry and remove them with a tissue.
4. If the crystal isn’t growing anymore you can create a new solution using the pervious steps and gently transfer the crystal once the solution is room temperature. The solution may need to be left overnight to cool before the crystal is added.
5. Once the experiment is over, remove the crystal extremely carefully from the beaker, dry it with a tissue and measure its length, width and height with a ruler. Compare the measurement to the original size of the crystal in your logbook.
Day 2: Crystal Observation
Day 2: My group of three including Remi, Vicky and I had a very rapid growth of #crystals. Yesterday we just had a beaker of solution and today we discovered the life of crystals. Our solution has made an odd 20 crystals that are about on average the size of a chick pea. #chickpea
Others beakers in the class did not grow as many crystals as ours. Overall our day 2 observation was very successful and it looks like we are going to have very large crystals by the end of this prac.
Day 3 Observation:
This is day three of growing my crysta, and there hasn't been much change since yesterday. The crystal is at 0.5 centimeters in height and the water is at just over 2 centimeters in height. The crystal is about the size of a small chickpea. The crystal has developed a smooth flat surface at the bottom, molding into the jars surface. The crystal is still small and is still growing. That is all that has happened for today.
Day 7 Observation:
We are currently on holidays and we have been told to do a weekly update on our crystals. SO i thought i would do one today which bring me to day 7 of growing our crystals. My crystal has grown slightly. It is about 0.6 centimeters and the width has gotten bigger as well. The solution has gone down a tiny bit. I