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Chapter 2 Science - properties of matter

Terms in this set (44)

Physical Properties
The characteristics of a substance that can be observed without changing the identity of the substance
What are ways we used to detect physical properties?
Use your senses! Color, size, texture, volume, mass and density
How do you know which characteristics are physical properties?
If the property involves changing the substance to a different substance, it is NOT physical.
Density
A measure of the amount of matter present in a given volume of a substance.
What is the formula for density?
mass/volume
Example - A glass marble has a volume of 5cm cubed and a mass of 13g. What is the density of the glass?
D= mass/volume - 13g/5cm (cubed)
D= 2.6g/cm cubed
It will sink because the density of water is 1.0 g/cm cubed
Is density measured the same for solids and liquids?
NO!
The density in solids is measured in grams per cubic centimeter (g/cm cubed)
The density in liquids is measured in grams per millimeter (g/mL)
1mL - 1 cm (cubed)
Does the density of the object stay the same, no matter how much of the substance you have?
Yes! The volume and shape changes NOT the density.
Physical change
a change in any physical property of a substance, not in the substance itself.
How is a physical change related to the substance's physical properties?
It changes a physical property, not the substance itself. For example, cutting paper will change the shape and volume, but will not change the substance of the paper.
How do you know if it is just a physical change?
If the substance is the same, then the changes it underwent were all physical changes.
Chemical properties
Describes how substances can form new substances
What are ways we used to detect chemical properties?
Combustibility, ability to rust, tarnishing, heat, is a new substance, changing into a different color
Chemical change
The change of one substance into another substance
What happens to atoms during a chemical change?
The atoms are rearranged
What is an indication of a chemical change?
A new substance forms
Signs of a chemical change?
Production of odor, change in temperature, change in color, formation of bubbles, formation of a solid
Does matter change form?
Matter always exists as either a solid, liquid or gas, but it can change from one state to another.
Why is a change in state a physical change, rather than an chemical one?
The identity of the substance does not change, just the state it is in does.
Melting
The process by which a solid becomes a liquid.
Melting point
The lowest temperature at which a substance begins to melt.
What happens to ice at 0 degrees celcius?
it melts
Describe the movement of molecules in a substance that is at its melting point?
Particles move fast enough to slide past one another
Freezing
The process by which a liquid becomes a solid
Freezing point
The temperature at which a specific liquid becomes a solid substance
What is the relationship between a substance's melting point and freezing point?
The freezing point of a substance is the same at that substance's melting point. so at that particular temperature, the substance can exist as either a solid or a liquid.
Evaporation
A process by which a liquid becomes a gas. It usually occurs at the surface of a liquid.
Describe the movement of particles in a liquid as it evaporates
Particles move past one another at different speeds. The particles near the surface that have the greatest speeds escape from the liquid and form vapor.
Sublimation
When a solid changes directly to a gas. Dry ice for example
Boiling
a process by which a liquid becomes a gas. Boiling produces bubbles.
Boiling point
Boiling can occur only when a liquid reaches a certain temperature.
How does the boiling point of a liquid at a high elevation differ from the boiling point at sea level?
It is lower so it takes longer to cook
Condensation
The process by which a gas changes its state to become a liquid
What happens to the particles when condensation is occurring?
When you cool gas it loses energy so the particles move more slowly and attraction among them cause droplets of liquid to form.
How can physical properties be used to identify a substance?
Compare the properties of unknown substances with the properties of known substances.
What is a useful property that can help a substance?
Density, heating properties, solubility, electric properties, and magnetic properties
Why can't you identify a substance on the basis of density alone?
More than one substance can have the same density
Heating properties
substances can respond to heating in different ways, which can help you identify a certain substance
Solubility
a measure of how much a substance dissolves in a given volume of a liquid
Electric properties
some substances that conduct electricity better than other, which means they allow an electric charge to move through them easily
Magnetic properties
substances that are attracted to magnets
what metal will a magnet attract?
steel
what method can be used to separate a solid from a liquid?
using a filter or letting the liquid evaporate
What are two situations in which separating substances are useful?
Making water safe to drink, separating aluminum cans from steel ones
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