Chemistry Flashcards
Definition of Matter
has mass; takes up space
States of Matter
Solid, Liquid, Gas, Plasma
Solid
- definite shape
- definite volume
- molecules move slowly (vibrate)
Liquid
- indefinite shape
* definite volume
Gas
- indefinite shape
* indefinite volume
Plasma
- indefinite shape
- indefinite volume
- molecules move really fast
- electrically-charged particles
Definition of Shape
a particular form
Definition of Volume
amount of space an object occupies (takes up)
Definition of Mass
amount of matter in an object
Kinetic Theory of Matter
the theory that all matter is made up of tiny particles that are in constant motion
Thermal Expansion
a characteristic of matter causing it to expand when heated and contract when cooled
What are particles like in a solid?
- very close together
* vibrate in position
What are particles like in a liquid?
- close together
* move over each other
What are particles like in a gas?
- seperate from one another
* move in all directions
What are particles like in a plasma?
- seperate from one another
- move in all directions
- gas-like
What are Crystalline Solids?
solids whose particles are arranged in repeating geometric patterns called crystals (most solids)
Examples of Crystalline Solids
Rock, Tree
What are Amorphous Solids?
solids that are not made out of crystals (they slowly change shape)
Examples of Amorphous Solids
Wax, Play-Doh
What do liquids do in a container?
they take the shape of the container
Examples of Liquids
Milk, Soda
What does a gas do in available space?
it expands and contracts to fill the available space
Examples of a Gas
Carbon Dioxide, Helium in a tank
What is the most common form of matter in the universe?
Plasma
What is most of our solar system’s mass composed of?
99% of our solar system’s mass is composed of the sun
Because of extremely high temperatures, particles in plasma do what?
move more rapidly, collide, and break into smaller charged particles
Examples of Plasma
Stars (i.e. The Sun), lightning, fire
Going from a Solid to a Liquid is called…
melting
Going from a Liquid to a Solid is called…
freezing
Going from a Gas to a Liquid is called…
condensation
Going from a Liquid to a Gas is called…
evaporation
Going from a Solid to a Gas is called…
sublimation
What is Evaporation?
change of a substance from a liquid state to a gaseous state
example of Evaporation
a puddle disappears on a sunny day
What is Condensation?
change of a substance from a gaseous state to a liquid state
example of Condensation
water on the outside of a cold glass
What is Sublimation?
a type of evaporation in which a solid changes directly to a gas without going through a liquid state
example of Sublimation
dry ice
What is a Change of State?
the conversion of a substance from one physical form to another
What is the difference between Endothermic Changes and Exothermic Changes?
energy is added during endothermic changes. energy is removed during exothermic changes.
The Freezing Point and Boiling Point of a substance…
are the same temperature
What do both Boiling and Evaporation result in?
a liquid changing to a gas
Condensation is…
the change of a gas to a liquid // the reverse of evaporation
What does Sublimation do?
Sublimation changes a solid directly to a gas
During a Change of State, what does the temperature of a substance do?
nothing; the temperature if a substance does not change during a change of state
What are Physical Properties?
a characteristic of matter that can be observed or measured WITHOUT CHANGING the identity of the matter
examples of Physical Properties
length, mass, volume, density, odor, color, state of matter, flexibility, texture, shape, magnetic
What are Chemical Properties?
a characteristic of matter that describes its ABILITY TO CHANGE into NEW MATTER with DIFFERENT properties
examples of Chemical Properties
flammability, reactivity (can react with another substance to form something new), potential to rust and/or rot
What is a Physical Change?
a change of matter from one form to another that affects one or more physical properties
What is a Chemical Change?
a change that occurs when one or more substances change into new substances with different properties
It could be a physical change if the substance…
- Changes shape
- Dissolves
- Changes State/Phase
- Changes color
What makes something a physical change?
No matter what, the substance is still the same
It could be a chemical change if a substance…
- Changes color because of a chemical reaction
- Gives off gas/bubbles (forcefully)
- Burns
- Forms a new substance
- Gives off heat
- Feels cold
What is an Exothermic Reaction vs. an Endothermic Reaction?
exothermic reaction - substance gives off heat
endothermic reaction - substance feels cold
What is an example of the physical property Solubility?
a flavored drink mix DISSOLVES in water
What is an example of the physical property Thermal Conductivity?
plastic foam protects you from hot liquid
What is an example of the physical property Malleability?
aluminum can be FLATTENED into sheets of foil
What is an example of the physical property Ductility?
copper can be PULLED INTO THIN WIRES
What is an example of the physical property Odor?
an onion gives off a very distinctive SMELL
What is an example of the physical property Density?
a golf ball has MORE MASS than a table tennis ball, but the VOLUMES ARE SIMILAR
When a substance undergoes a physical change, what is not changed? What is changed?
its composition does not change. only a physical property is changed.
The chemical property that describes the ability of 2 or more substances to combine to form new substances is called…
reactivity
The ability of a substance to burn is a chemical property known as…
flammability
An iron nail is reactive with…
oxygen in the air (reaction: rust)
What is a Characteristic Property of matter?
either a physical or chemical property that scientists use to help identify & classify matter
Does a substance always have chemical properties?
yes, even though they are difficult to observe
How do you know that baking a cake involves chemical changes?
Baking a cake involves chemical changes because the cake’s properties differ from the properties of the ingredients before they were baked.
Why are chemical changes hard to reverse?
because they change the identity of the substances involved
What is the most important question to ask to determine whether a change is physical or chemical?
Did the composition change? (chemical ~ yes; physical ~ no)
What is the name of the process by which water is broken down into hydrogen and oxygen using an electric current?
electrolysis
What are Elements?
They’re pure substances made of only 1 kind of atom.
What are Atoms?
They’re tiny structures found in all matter.
What do most substances contain?
many different atoms. only the elements contain only 1 kind of atom
Elements:
- One kind of atom
- Pure
- Seperated in nuclear reactions
Compounds:
- 2 or more kinds of atoms chemically bonded
- Pure
- Seperated in chemical reactions
Mixtures:
- 2 or more elements or compounds physically together
- Not pure
- Seperated in physical reactions
A substance that cannot be seperated into simpler substances by physical or chemical means is…
an element
What do elements contain only 1 of?
contains only 1 type of atom
Where can elements be found?
on the periodic table
What are the 3 major categories of elements?
metals, nonmetals, and metalloids
examples of elements:
Helium, Iron, Calcium
A subtance made of 2 or more elements that are chemically combined is…
a compound
What does a compound have a specific ratio of?
a specific ratio of elements (formula)
How do the properties of the compound compare to the elements it’s made from?
properties of the compound are different than the individual elements it’s made from
examples of compounds:
Table Salt -> Sodium & Chlorine: NaCl
Sugar (sucrose) -> Carbon, Hydrogen, & Oxygen: C H O
12 11
A combination of 2 or more substances not chemically combined is…
a mixture
Do the properties of substances change when forming a mixture?
no; no change in original properties of substances
Is there a specific ratio of substances when forming a mixture?
no; formed by using any ratio of substances (# of choc. chips in a cookie doesn’t matter; it’s still a choc. chip cookie)
examples of mixtures:
Hot Chocolate, Bowl of Cereal, Salt Water
This represents the element. While te English name sometimes matches, the Latin name was sometimes used to create this.
Element Symbol
This is the most commonly used word for the element.
Element Name
Designated by the number of protons in the nucleus, this determines hotizontal placement on the table.
Atomic Number
This is determined by the weight of an atom.
Atomic Mass
LABEL THE PARTS:
6
C
Carbon
12.01115- Atomic Number
- Element Symbol
- Element Name
- Atomic Mass
Periodic Table of Elements:
the arrangement of elements according to repeating changes in properties
How are elements arranged?
Elements are arranged in order of their ATOMIC NUMBER - not atomic weight
What are vertical columns called, and what do elements in each vertical column have in common?
Vertical columns are called groups or families. There are 18 groups. Elements in each group or family have similar properties.
What determines element’s properties?
Similar electron arrangements determine element’s properties. The number of electrons in the outer energy level determines the chemical properties of that element.
What are horizontal rows of elements called?
Horizontal rows if elements are called periods.
Where are elements that are METALS placed on the periodic table?
All elements to the LEFT of the stair step line are METALS (except hydrogen)
What are common properties of metals?
metals are commonly solid at room temperature, shiny, and good conductors of heat & electricity
Where are elements that are NONMETALS placed on the periodic table?
All elements to the RIGHT of the stair step line are NONMETALS
What are common properties of nonmetals?
Nonmetals are commonly gases or brittle solids at room temperature, and most do not conduct heat & electricity well
Where are elements that are METALLOIDS placed on the periodic table?
All elements NEXT TO the stair step line are METALLOIDS
What properties do metalloids have?
Metalloids have properties of both metals & nonmetals
What elements are TRANSITION ELEMENTS?
All elements in GROUPS 3-12 are TRANSITION ELEMENTS
What are transition elements?
Transition elements transition from very metallic to nonmetallic properties
Why are elements in group 18 called the noble gases?
They don’t react with other elements.
What does it mean if an element is synthetic?
It means the element is manmade.
Separation of Mixtures:
Evaporation
a mixture is heated until the water changes from a liquid to a gas. the water vapor can be collected & condensed back into liquid form. the reamainin substance has then been separated from the water.
Separation of Mixtures:
Sifting/Filtering
a mixture is passed through a screen that separates large particles from small particles. the smaller particles pass through while the larger particles are collected on the screen.
Separation of Mixtures:
Weight
a special machine called a centrifuge spins a mixture to separate substances with different masses. the heavier substance is forced to the bottom & the liquid is siphoned off.
Separation of Mixtures:
Magnetism
a magnet is used to separate magnetic materials from those that are not magnetic.
