Unit 2 Flashcards
study
What is matter?
all the stuff that exists in the universe.
how do scientists define matter?
anything that has mass and occupies space
what is mass?
a measure of the amount of matter in a substance or an object
What is the basic SI unit of mass?
The kilogram. smaller masses may be measured in grams.
What does volume measure?
The amount of space that an object or substance takes up.
Name the different units that might be used to measure volume.
Basic SI unit is the cubic meter.
cm cubed, liters, and milliliters are also used.
Explained the displacement method.
- Add water to a measuring contain and record the volume.
- place the object in the water and record the new volume.
- subtract the first volume from the second volume. The difference represents the object’s volume.
What is a physical property of matter?
properties that can be measured/observed without matter changing to an entirely different substance.
What is an extensive physical property?
properties that depend on the amount of matter present. Ex. mass, weight, volume, length
What is an intensive physical property?
Properties that do not depend on the amount of matter present.
What is a physical change?
a change in one or more physical properties without any changes to the chemical properties
examples of intensive physical properties??
color, odor, luster, malleability, ductility,conductivity, hardness, melting/freezing point, boiling point, density
Why are physical changes often easy to reverse?
The chemical properties of matter remain the same in a physical change, so a physical change is often easy to reverse.
what are the 4 states of matter and what are their shape and volume like?
solid - definite shape and volume
liquid - indefinite shape, definite volume
gas - indefinite shape and volume
plasma - an electrically charged gas
which states of matter are most common on earth
solid, liquid, and gas
what type of property is a state of matter?
a physical property because a given kind of matter has the same chemical makeup and the same chemical properties, regardless of state
What is a solid?
A state of matter in which particles of matter are tightly packed together.
why does a solid have a fixed shape and a fixed volume?
This holds the particles rigidly in place. They can not flow easily.
What is the difference between a crystalline and amorphous solid?
Crystalline solids have particles that are arranged in a regular repeating pattern. They form Crystals. Ex. Table Salt
Amorphous solids have particles that are arranged more or less at random. They do not form crystals. Ex. Cotton Candy
State the properties of matter in the liquid state
A liquid is a state of matter in which particles slip past one another and take the shape of their container
The particles cannot pull apart and spread out to take the volume of their container.
-Definite shape and volume
-flows easily
-lots of free space between particles
What is a gas?
Gas is a state of matter in which particles of matter can pull apart from each other and spread out
Why does a gas expert force?
Gas particles are constantly moving, which creates force
What does pressure mean?
The amount of force pushing against a given area is called pressure
What is the kinetic theory of matter?
particles of matter are in constant motion
true or false: solids have the least kinetic energy and gasses have the most.
TRUEEEEEEEE
Define change of state
A change of state occurs whenever matter changes from one state to another
Identify processes that change matter to a liquid state
Melting, freezing, sublimation, deposition, condensation, evaporation
Why must energy be absorbed to change liquid to a gas?
energy is always involved in changes of state. Particles of matter either absorb or lose energy when matter changes from one state to another
What is a mixture?
A physical blend of 2 or more components, each of which retains its own identity and properties in the mixture
What is a homogeneous mixture?
a mixture in which the composition is uniform throughout the mixture. All solutions are homogeneous
Define heterogeneous mixture.
A mixture in which the composition is not uniform throughout the mixture
What is a phase?
A phase is a separate layer in a heterogeneous mixture
Why is it important to separate materials from a mixture?
In a chemical reaction, it is important to isolate the component(s) of interest from all other materials so they can be further characterized.
What is filtration?
Separation of a mixture’s components through difference in particle size.
What is decanting?
A fancy term for separating 2 components by pouring
What is Distillation?
used to separate 2 liquids based on their differences in boiling point
What is magnetism?
Used to separate magnetic substances
What is evaporation?
Removing a liquid to leave a solid behind
What is Centrifuge?
separates substances of different densities using a fast rotational motion
What is Chromatography?
Separates 2 substances by using a mobile phase and a stationary phase.
What is an element?
A pure substance that cannot be broken down into any other substance.
How many naturally occurring elements are there?
92
Why can an element be identified by its properties
each element has a unique set of properties that is different from the set of properties of any other element
When did scientists begin discovering all of the elements?
500 years ago.
What is an atom?
The smallest particle of an element that still has the properties of the element
How are atoms related to elements?
All the atoms of an element are like on another and are different from the atoms of all other elements
What are compounds?
A pure substance when 2 or more elements have chemically combined through a chemical reaction to form a new substance. Ex. NaCI - sodium chloride (salt) or H^2O (water)
True or false: a compound always has the same elements in the same proportions
TRUEEEEEE
How do the properties of compounds compare with the properties of the elements that form them?
The properties of compounds may be very different from the properties of the elements that form them
Compare and contrast crystals and molecules.
Some compounds form rigid frameworks called crystals. Other compounds form individual molecules
What is a molecule?
The smallest particle of a compound that still has the compound’s properties
What is a chemical property?
Chemical properties are properties that can only be measured or observed only when matter undergoes change to become an entirely different kind of matter
Define the chemical property called reactivity.
The ability of matter to react chemically with other substances
What is flammability?
The ability of matter to burn
What happens in any chemical change?
A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties
List 5 signs that a chemical reaction has occurred.
Release of bubbles, production of odor, change of color, release of heat, release of light.
Why can chemical reactions often not be reversed?
They result in different substances
What is involved in all chemical reactions?
Reactants and products.
How are chemical reactions written?
general chemical formula. Reactants - products
How are bonds involved in chemical reactions?
bonds break and reform during chemical reactions
How do reactants change into products during a chemical reaction?
Reactants and products contain the same atoms, but they are rearranged during the reaction, so reactants and products are different substances
How can you tell whether a change in matter is caused by a chemical reaction?
color, temperature, formation of a gas, precipitate,
What is a chemical symbol?
a one or 2 letter designation of an element
What are compounds?
combinations of 2 or more elements
what is a chemical formula?
an expression that shows the elements in a compound and the relative proportions of those elements.
From where are the names of many elements derived?
the Latin name for the element
what is the law of conservation of mass?
matter cannot be created or destroyed
