Properties of Magma SECTION 3-2

OBJECTIVES F Identify some physical and some chemical properties of magma. F Explain why some fluids flow more slowly than other fluids. F Explain what two factors determine the viscosity of magma.

ELEMENTS Remember from chemistry what the definition of an element is. An element is a pure substance made of all like atoms that can’t be broken down any further. What are some examples of elements? Hydrogen, Carbon, Oxygen, Nitrogen, Sodium, Gold. Where do we look to find the list of elements?

THE PERIODIC TABLE OF THE ELEMENTS

COMPOUNDS What are compounds and how are they different from elements? Compounds are made of combinations of two or more elements chemically combined to make a new and different substance. What are some examples of compounds? Water, Sugar, Salt, Carbon Dioxide.

PHYSICAL AND CHEMICAL PROPERTIES Every substance has it’s own particular set of chemical and physical properties that make it a unique substance. These properties can be used to identify a substance and predict how it will react and behave.

PHYSICAL PROPERTIES A physical property is a property that can be observed without changing that substance into something different. What are examples of physical properties? Density Color Hardness Magnetism Boiling Point-Freezing Point-Melting Point

CHEMICAL PROPERTIES A chemical property is a property that involves changing one substance into another substance. What are some examples of chemical properties? Ability to burn or react with other substances. Tarnishing or rusting. Do you remember the 5 indications of a chemical change?

INDICATIONS OF A CHEMICAL CHANGE 1) A solid is produced 2) A gas is produced 3) Water is produced 4) Heat is released or absorbed 5) An unexpected color change

Viscosity is a fluids resistance to flow. In other words, something with a high viscosity does not like to flow easily. An example of this might be molasses. A low viscosity is something that flows easily. Can you think of a liquid that flows easily. Water VISCOSITY

Temperature also plays a role in viscosity. Relatively speaking, the higher the temperature the lower the viscosity. Therefore, the hotter the magma’ the faster it flows. Magmas with a higher silica content will have higher frictions between the atoms. What will this do to their viscosity? They will have higher viscosity. Which means: They will flow more slowly THINGS THAT AFFECT VISCOSITY OF MAGMA Silica ContentTemperature

HOW DOES THIS AFFECT ERUPTIONS? High ViscosityLow Viscosity

High Viscosity High viscosity magmas generate explosive eruptions.

Low Viscosity Low viscosity magmas generate quiet eruptions.

How would you describe this eruption? Explosive What does this tell us about its magma? It has a high viscosity. So what do we know about the silica content? It has high silica content. What about temperature? It’s relatively low. IDENTIFY THE FOLLOWING

How would you describe this eruption? Quiet What does this tell us about its magma? It has a low viscosity. So what do we know about the silica content? It has low silica content. What about temperature? It’s relatively high. IDENTIFY THE FOLLOWING