7.2 properties of magma

1. 7.2 properties of magma • Key terms: element, compound, physical property, chemical property, viscosity, silica, pahoehoe, aa • Key concepts: Why is it helpful to know the physical and chemical properties of a substance? • What causes some liquids to flow more easily than others? • What factors determine the viscosity of magma?

2. Physical and chemical properties • An element is a substance that can’t be broken down further. • A compound is a substance made of two or more elements that have been chemically combined. • Each substance has a particular set of physical and chemical properties. These properties can be used to identify a substance or to predict how it will behave.

3. Physical properties • A physical property is anything that can be observed without changing the composition of the substance. • Examples: freezing point, melting point, malleability, density, hardness, magnetism

4. Chemical properties • Any property that produces a change in the composition of matter. • Examples: burning, tarnishing, rusting

5. Viscosity • Viscosity is the resistance to flow. High viscosity – high resistance to flow. Low viscosity – low resistance to flow. • High – honey. Low – water.

6. Viscosity of magma • Depends upon its silica content. Not all magma has the same viscosity. • Silica content – magma’s main ingredient. • Made up of particles of the elements oxygen and silicon. • Helps determine the viscosity – more – higher • Magma high in silica produces light colored magma that doesn’t travel far

7. Temperature • How does temperature affect viscosity? • Viscosity INCREASES as temperature DECREASES. • Pahoehoe (heeeeheeheeeheeeeeee!) and aa are two types of lava. • Pahoehoe is fast moving hot lava with low viscosity • Aa is cooler and slower moving with high viscosity