Year 9 Science- Steph Bounos
.Initial Research - Thursday 12th September
1. What is a crystal?In physics, the term "crystal" describes a solid substance with internal symmetry and a related, regular surface pattern. Inside a crystal, all the atoms are arranged in the same pattern. This is what makes crystal uniform and makes parts of it the same shape. It also allows light to travel through it in interesting ways
2. What substances can be used to make crystals?Crystals can be made from all sorts of things. The crystals we will be making will be large aluminium potassium sulphate dodecahydrate crystals. Crystals can easily be made from household items like salt and sugar.
3. What are some examples of crystals in nature? What household items can you also grow crystals from?
Snow flakes, Diamondst, Sand, Amethyst, Sapphire and Ruby are all common crystals which are found in nature. Some household items which you could use are sugar and table salt.
4. Explain the process of crystal growth.Sodium and Chlorine atoms both share a pair 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.
5. Explain how crystals can grow in different shapes and sizes.Crystals grow into certain shapes because the atoms or molecules join together in a pattern that repeats itself over and over to create a certain shape. A crystal grows by adding atoms or molecules to all its sides in the exact same pattern as the atoms and molecules that were added before. Because each different crystal is made up of a different building block (atom or molecule)they eachhave a different structure or shape. This is why salt crystals are square in shape while Epsom salt crystals are long and rectangular.
6. Outline a few different 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.
7. What effect do crystals have on light travelling through them ?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.
8. What are the optimum conditions for crystals 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
9. make a plan for the next week as a list:
Day 1 - Tuesday
- 2 250ml beakers
- Filter Funnel
- Filter paper
- Hot water
- 25g potash alum
- Stirring rod
- Place 25g of potash alum in a beaker (250ml or bigger.)
- Add 170ml of warm water.
- Stir the mixture until all the crystals have dissolved.
- Filter the solution through a filter funnel (with filter paper) into a clean beaker.
- Cover the beaker with a watch glass or another piece of filter paper.
- Leave in a cool sheltered place overnight.
Day 2 - Wednesday
Overnight the bottom of the beaker should have become covered with a small layer of crystals. If the are no crystals on the bottom, follow the steps below. If there are crystals, move onto session 3.
- Add one potash alum crystal to the mixture.
- Cover and leave overnight.
- Scratch the bottom of the beaker with a glass stirring rod.
- Cover and leave overnight.
Day 3 - Thursday
- 2 250ml beakers
- Overnight, the bottom should have become covered with a layer of small crystals.
- Carefully pour the liquid that remains in the beaker into a clean beaker.
- From the crystals at the bottom of the beaker choose one good symmetrical crystal to be used as a 'seed' for a big crystal.
- Remove this crystal from the beaker and put it into the other beaker. Try to put it into the middle.
- Take a picture of the crystal next to a ruler and mark the height of the liquid on the beaker. Record the date.
- Cover the beaker with paper and put it in a safe spot that isn't in direct sunlight or near a heater.
This is day 1 of my crystals, Today my group completed the practical component of the experiment. We combined the potash alum with hot water and filtered the solution into a clean beaker. Hopefull by tomorrow we will have some crystals start to grow.
This is day 2 of my crystals, they have formed over night, and should continue to grow over the next couple of weeks. I have been leaving them in the sun, with filter paper on the top. I am hoping to see more growth in them in the next 2 weeks.
observations: This is my crystals on day 3. At the moment they have not made any progress since day 2. I am hoping that by tomorrow they will have grown. I am going to be keeping them in a warm, sunny and dry place.
observations: This is my crystals in week 2, they have been rapidly growing in the last 5 days. At the moment the water level is at 1.2 cm. The crystals have almost doubled in size since I had last checked them.
These are the pictures of my final crystal. The water in the jar has not full evaporated yet. The water level at the moment is at 1.5 cm. It has reduced by 0.5 cm. The largest crystal which I have at the moment is 10 mm long. The table below summarises the water level and growth of my crystal. My crustal grew continuously for about 5 days and then suddenly stopped growing. The above pictures show the ex