Transcript Physical Property

Chemistry: the study of the composition, structure, and properties of matter,
the processes that matter undergoes, and the energy changes that accompany these
processes.
Composition refers to identifying the elements that are present in a substance.
For example: water is composed of 11.2% hydrogen and 88.8% oxygen by mass
Structure refers to specifically how the elements are combined to make a
substance what it is.
For example: in water, there are two hydrogen atoms bonded to a single
oxygen atom like the structure shown here:
H–O–H
Properties refer to how a substance behaves: things like the temperature at
which it would melt or freeze, how dense it is, or how it would react with
another substance.
For example: the freezing point of water is 0.0oC, water has a density of
1.0 g/mL, and water will react with sulfur trioxide to make sulfuric acid
Branches of Chemistry: main areas of study within the field of chemistry
Organic
Physical
Inorganic
Analytical
Theoretical
Biochemistry
The study of compounds that generally do not contain carbon is called
_________________________________ chemistry.
The identification of components and composition of materials is called
_________________________________ chemistry.
The study of substances and processes occurring in living things is called
_________________________________ .
The study of most carbon-containing compounds is called
_________________________________ chemistry.
The use of mathematics and computers to study chemical behavior is called
_________________________________ chemistry.
The study of properties and changes including energy changes of matter in is called
_________________________________ chemistry.
Since chemistry is the study of matter, we begin by defining matter.
Matter: anything that has mass and takes up space (has a volume). Anything that
is not energy is matter.
Mass: a measure of how much matter is present.
An element is a substance that can not be broken down into simpler substances.
An element contains only one type of atoms.
A compound is a substance that can be broken down into simpler substances and
contains two or more different elements.
An atom is the smallest amount of matter than can be identified as a specific
element. An atom is made up of smaller pieces of matter (protons, neutrons and
electrons). The periodic table is used to identify all of the known elements.
When studying matter, we study properties of matter. Properties tell us
something about the way the matter behaves or what it is like.
Extensive Property: a property that depends upon how much matter is present.
Examples include things like: mass, volume, length, etc…
Intensive Property: a property that does not depend upon how much matter is
present.
Examples include things like boiling point, density, hardness, etc…
Physical Property: a property that can be studied without changing the substance
into a different substance.
For example, we can study water to find its boiling point. We can find
the temperature where water boils, but the water is still water.
Chemical Property: a property that relates to how a substance changes into a
different substance.
For example, when iron rusts it becomes iron oxide (an orange solid).
When studying matter, we also study changes in matter.
Change: a change is an action-something is happening or is failing to happen now.
Physical Change: a change that does not change the substance into a different
substance.
For example, breaking glass does not change the glass into a different
substance.
Chemical Change: a change that causes a substance to change into a different
substance.
For example, burning paper changes the paper into carbon dioxide and
water.
Properties versus Changes
Property: a property is something that describes how a substance may behave,
but it does not have to happen now.
Change: a change is an action-something is happening or is failing to happen now.
A physical property of glass is that it is rather brittle and can break (rather than bend).
A physical change for glass is when we are actually breaking the glass.
A chemical property of sodium is that it will react violently with water.
A chemical change for sodium is when it is actually reacting with water.
Physical versus Chemical and Properties versus Changes
Underline any property or change that is chemical.
Put a star next to anything that is a change.
iron is hard
butter is melting
gold is inert
lead is dense
aluminum is malleable
the egg is rotting
copper sulfate is blue
water boils at 100oC
bacon is frying
he is ripping the paper
copper conducts electricity
paper burns easily
wax is melting
sodium will react with water
gold is expensive
States of Matter
There are four states of matter (three normal and one that requires special
circumstances to maintain).
Solid: particles are rigidly held in place and can not move about within the substance
Liquid: particles are able to move about but they stay relatively close together
Gas: particles move about and are relatively very far apart from one another
Plasma: is a gaseous type of state where some of the atoms present have lost their
electrons (gaseous atoms, ions and electrons are all present together). This is
considered to be a high energy state of matter and if it loses energy it will revert to the
gas state.
Changing from one state to another is a physical change. The conditions when a
substance changes from one state to another are physical properties.
States of Matter Continued:
Solid to Liquid
Changing from a solid to a liquid is called melting or fusion and melting point is a
physical property
Liquid to Solid
Changing from a liquid to a solid is called freezing or solidification and freezing
point is a physical property (note that the melting point and the freezing point are the
same temperature for a given substance).
Liquid to Gas
Changing from a liquid to a gas is called boiling or vaporization and boiling
point is a physical property
Gas to Liquid
Changing from a gas to a liquid is called condensation
Solid to Gas
Changing from a solid to a gas is called sublimation
Gas to Solid
Changing from a gas to a solid is called deposition
Pure Substance versus Mixtures
A pure substance contains only one substance.
Pure substances are either elements of pure compounds
Mixtures contain more than one pure substance.
Mixtures are either Homogeneous or Heterogeneous
Homogenous
Homogeneous mixtures are also called solutions. A homogeneous mixture is a
mixture that is uniform in composition (mixed at the atomic level-we usually
say that one substance is dissolved in the other one). An example is sugar
water-the sugar dissolves in the water and cannot be seen.
Heterogeneous
Heterogeneous mixtures are not uniform throughout (we can usually see that there
are two or more substances present). An example is salt and pepper-we can see the
pepper specs mixed with the salt crystals.
The periodic table is broken down into three main categories of elements.
There are seven periods (horizontal rows). The vertical columns are called groups.
1
2
3
4
5
6
7
Non-metals
Metals
Metaloids
11
Metals are elements that are:
good conductors of heat
good conductors of electricity
can be drawn into a wire (called ductility)
can be hammered into flat sheets (called malleability)
Non-Metals are elements that are the opposite of metals:
poor conductors of heat
poor conductors of electricity (called insulators)
are brittle if they are solids
Metalloids are elements that have properties of both metals and non-metals
Practice Questions:
In which branch of chemistry is the focus studying the composition or makeup of a substance?
A. Biochemistry
B. Inorganic
C. Theoretical
D. Analytical
In which branch of chemistry is the focus studying compounds that contain
carbon?
A. Biochemistry
B. Theoretical
C. Organic
D. Physical
A dependent variable is ________________________________.
A. something that remains constant during an experiment.
B. something that responds to changes that we make during an experiment.
C. something that we choose to change during an experiment.
D. something that we use to compare our results to.
Which of the following is an example of pure research?
A.
B.
C.
D.
producing heat resistant plastics for use in household ovens
finding ways to reduce the rusting of iron ships
creating synthetic elements to study their properties
searching for fuels other than gasoline to power cars
Which of the following represents a compound?
A. Salt Water
C. Pizza
B. Carbon dioxide
D. Calcium
Which of the following terms correctly describes the following: an acidic
solution will turn pink if enough base is added?
A. Physical change
C. Chemical change
B. Physical property
D. Chemical property
Which of the following terms correctly describes the following: a crystal vase is
breaking as it hits the floor?
A. Physical change
C. Chemical change
B. Physical property
D. Chemical property
Choose the correct classification for the following: wax is melting.
A. Physical change
C. Chemical change
B. Physical property
D. Chemical property
Which of the following does NOT represent a physical change?
A. Water vaporizing
C. Steam condensing
B. Iron rusting
D. Glass breaking
Choose the correct classification for the following: a cigarette will burn when it is lit.
A. Physical property
C. Chemical property
B. Physical change
D. Chemical change
Choose the correct classification for the following: aluminum is not as dense as
lead is.
A. Physical property
B. Physical change
C. Chemical property
D. Chemical change
Choose the correct classification for the following: salt dissolved in water.
A. Homogeneous Mixture
C. Element
B. Heterogeneous Mixture
D. Compound
Choose the correct classification for the following:
A. Homogeneous Mixture
C. Element
fog.
B. Heterogeneous Mixture
D. Compound
Which of the following does NOT represent a homogeneous mixture?
A. Oxygen
C. Brass is an alloy of copper and zinc
B. Sugar dissolved in water
D. Blue glass
Which of the following is an extensive property?
A. Boiling point
C. Volume
B. Density
D. Freezing point
What is the name of the phase change when going from a solid to a liquid?
A. Condensation
C. Deposition
B. Vaporization
D. Fusion