What is Chemistry?

1
What is Chemistry?
What is Chemistry the Study of..?
Chemistry is the Study of Matter and the Changes
it can undergo.
What is Matter?
1. Matter is anything that has mass and volume
(takes up space).
2. Matter is anything you can put in a balloon
and keep in there. Mr.D
What is most Matter made of?
Generally, Matter is made of Atoms.
What is Not Matter?
Light Energy, Sounds, Heat (Thermal) Energy
What kinds of Changes can Matter undergo?
1. Physical Changes, 2. Chemical
Changes, and 3. Nuclear Changes (on hold
until Unit 3)
2
Physical Changes and Physical Properties
What are Physical Changes?
Physical Changes are changes in state or phase
(solid, liquid, gas) or shape without changing
the composition of matter. Still the Same
Stuff.
What are some examples of Physical Changes?
Melting, freezing, boiling, condensing, cutting,
molding, grinding, crushing
What are Physical Properties?
Physical Properties are those properties that can
be observed without changing the composition of
the sample.
What are some examples of Physical Properties?
Melting point temperature, boiling point, color,
hardness, density
3
Chemical Changes and Chemical Properties
How can one describe a Chemical Change?
A starting material (Reactant) is changed into a
new material (Product) with different
properties.
Generally, atoms are rearranged and bonded in a
different way to form a new substance.
new different
How can one Identify a Chemical Change?
The presence of a new material with
different Properties is evidence of a Chemical
Change.
What are Chemical Properties?
Chemical Properties are the Chemical Changes a
substance may undergo.
Describe the Chemical Change illustrated here.
Oxygen and methane rearrange their atoms to form
water and carbon dioxide.
4
Pure Substances
What is an Element?
A sample of matter is an Element if it contains
only one type of atom.
Elements cannot be decomposed into anything
simpler. Except sub-atomic particles
What is a Compound?
Atoms of Different Elements may chemically bond
together to form Compounds.
What are the characteristics of a Compound?
1. Elements combine in a Definite Ratio due to
specific bond formation.
2. The Physical and Chemical Properties of
Compounds are Different from the Elements from
which they form.
5
Most Materials are Mixtures
What are the Characteristics of Mixtures?
Substances (Elements and/or Compounds) can be
Combined Without Chemically Bonding.
1. Therefore, the Proportions of components in a
Mixture can vary.
2. The Substances retain their identity and the
properties of the mixture are a blend of the
properties of the individual components.
Distinguish between Homogeneous vs.
Heterogeneous Mixtures
Homogeneous Mixtures have a uniform composition
throughout.
The Different Components can be seen in a
Heterogeneous Mixture.
What type of mixture is an Aqueous Solution (aq)?
An Aqueous Solution is a Homogeneous Mixture.
Water is the Solvent.
6
Methods to Classify Types of Matter
7
Classification of Matter
All Matter
Can it be separated by Simple Physical means?
Yes
No
Mixture
Pure Substance
Can it be decomposed by Chemical means?
Is the Composition Uniform?
Yes
No
Yes
No
Homogeneous Mixture
Heterogeneous Mixture
Compound
Element
8
Methods Used to Separate Different Parts of a
Mixture
Describe the process of Distillation.
1. The component with the Lowest Boiling Point
Vaporizes Most Rapidly.
2. The Vapors Cool and Condense, and flow into a
separate container.
Describe the process of Centrifugation.
Spinning a mixture causes the Denser Components
to settle to the bottom faster.
9
More Methods of Separation of Components of a
Mixture
Describe the process of Filtration.
Larger particles are trapped while smaller
particles travel through a filter.
Filter Paper will Not separate the components of
an aqueous solution (aq).
Describe the process of Paper Chromatography
Pigments in a Mixture Separate due to different
affinities for a specific Solvent as it travels
up the paper.
10
Compounds vs. Mixtures
Different components combined in a definite
ratio.Why?
Different components can combine in any
ratio..Why?
Compounds make specific Chemical Bonds while
Mixtures do not.
Electrolysis Using electricity to Decompose
Water into its individual components
Characteristics of mixtures are a combination or
blend of characteristics of individual
components.Why?
Characteristics of compounds are different from
individual components..Why?
Forming a Compound is a Chemical Change, thus a
new material forms.
Difficult to separate individual components.Why?
Easy to separate individual componentsWhy?
Chemical Bonds are Difficult to Break.
Mixtures are Not Chemically Bonded.
11
Classify each of the following as one of the four
types of matter. Explain each choice.
Link to Quia Game Types of Matter
Iced Tea with lemon and sugar
Pure Substance Compound
NaCl (l)
Heterogeneous Mixture
Air
Solution Homogeneous Mix.
NaCl (aq)
(aq) is ALWAYS a Homogeneous Mixture
Sea Water
Probably a Heterogeneous Mixture,
possibly Homogeneous
CO2 (g)
Pure Substance Compound
Wood (oak)
Heterogeneous Mixture
Cheese Pizza
Heterogeneous Mixture
Carbon (s)
Pure substance Element
Quartz Crystal (silicon dioxide)
O2 (g)
Pure Substance Compound
Pure substance Element
Paper
Homogeneous Mixture
Heterogeneous Mixture if made w/ real lemons
Distilled Water
Lemonade
Pure Substance Compound
Tap Water
Pure substance Element
Zinc Powder
Homogeneous Mixture
NaCl (s)
Pure Substance Compound
Brass
Alloy Homogeneous Mixture of Metals
12
Simple Particle Diagrams
How can Simple Particle Diagrams Illustrate the
Phases of Matter?
Link to Phases of Matter in Containers
Link to Phases of Matter at the Molecular Level
Link to Interactive Phases of Matter
How can Simple Particle Diagrams Illustrate the
Types of Matter Elements, Compounds, and
Mixtures?
Link to Examples of Elements, Compounds, and
Mixtures (or see next slide)
Link to Elements, Compounds and Mixtures
Interactive Quiz
13
Describe the Types of Matter
http//www.docbrown.info/page01/ElCpdMix/EleCmdMix
.htmimages
14
http//www.docbrown.info/page01/ElCpdMix/EleCmdMix
.htmimages