Lesson 2
Crystals and rocks
Objectives:
Know that all substances are made of atoms and atoms can bond together.
Know that there are simple substances called elements which can join together to make compounds.
Know that characteristics like hardness can be tested in the laboratory and these are linked to the atoms and bonds.
Be able to carry out a simple hardness testing experiment.
Know that substances can melt and freeze depending on the temperature.
Be able to link the sizes of crystals in rocks with the speed the liquid cooled.
Know the difference between magma and lava.
Be able to explain the terms solute, solvent, solution and saturated.
Be able to explain how stalactites form.
INTRODUCTION
PART A
Watch the video and follow the instructions. (There is about 1 minute of the "Scientific Eye video missing, but keep watching because it comes back at the end.
Exercise - Copy and complete this paragraph on paper.
All substances are made of a................................. They can arrange themselves in a regular, 3-dimensional pattern which forms a c.................................... Atoms are joined together by b........................... In a crystal of diamond all of the bonds between the c.............................. atoms are very strong which makes the diamond very h.................. Another form of carbon is g............................., in this some of the bonds are weak so it is s...........................
PART B
Watch the video and follow the instructions.
Exercise - Copy these questions and answer them on paper
Work out the hardness of the following:
- It can be scratched by a finger nail.
- It can be scratched by a copper coin but not by a fingernail.
- It can be scratched by a steel nail but not by a copper coin.
- It cannot be scratched by a steel nail.
PART D
Watch the video and follow the instructions.
Exercise - draw the thermometer chart for iron, then copy and answer these questions.
- What is the state of iron at 1000 degrees C?
- What is the state of iron at 2870 degrees C?
- What is the state of iron at 2862.5 degrees C?
- What is the arrangement of the particles in iron at 1800 degrees C?
PART E
Watch the video and follow the instructions.
Exercise - Copy and complete this paragraph on paper
Igneous rocks are made of crystals. They form when m........................... or l............................... cools down. Magma is under the surface of the Earth, so it cools down s.............................. forming an igneous rock with b................. crystals. Small crystals form when lava on the surface cools down q.............................................
PART F
Watch the video and follow the instructions.
Exercise - Copy and answer these questions on paper.
- What word means " a liquid, that makes a substance dissolve"?
- What word means "a substance that dissolves"?
- What word means "a mixture of a solute and a solvent"?
- What word means "a solution that cannot dissolve more solute"?