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Matter Matter, does it matter?
Yes…it does!
Chemistry is the study of matter and the changes it undergoes.
Matter
Something is considered to be matter if it:
Has mass
Takes up space What are some examples?
We define matter by using two criteria.
Classifying matter - Why?
1. To organize what we have
2. When things are organized – we know what we have
3. And more importantly, we know what we do NOT have.
Matter
Does it have a fixed formula? Yes No
Substance Mixture*Having a fixed formula *No fixed formula*Cannot be separated by *Can be separated physical means by physical means
Classifying matter
Substances Can it be separated chemically?
No Yes
Element Compound*Simplest form of matter *Two or more elements
*Cannot be broken down further * Can be broken down
*Found on the periodic table
H2O -> H2 + O2
Classifying matter
Substances: element or compound Elements- simplest kind of matter
cannot be broken down any simpler and still have properties of that element!
all one kind of atom. Compounds are substances that can be
broken down only by chemical methods when broken down, the pieces have
completely different properties than the original compound.
made of two or more atoms, chemically combined (not just a physical blend!)
Symbols & Formulas Currently, there are 117 elements -Only 92
of the 115 presently known elements occur naturally.
Elements have a 1 or two letter symbol, and compounds have a formula.
An element’s first letter always capitalized; if there is a second letter, it is written lowercase: B, Ba, C, Ca, H, He
Some elements pair up and only exist as diatomic molecules
Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, and Bromine are always found as diatomic molecules:
How do I remember this? H N F O I Cl Br •HONClFIBr (say HONKLE-fibber) •BrINClHOF (say Brinckle-hoff) •I Have No Bright Or Clever Friends •ClIF H Bron •HOFBrINCl Twins (twins because they exist in pairs) •There are seven such elements. The first one is the first element Hydrogen; the rest form a 7 on the periodic table: N, O, F across, then going down Cl, Br, I.
Elements vs. CompoundsCompounds can be broken down
into simpler substances by chemical means, but elements cannot.
A “chemical change” is a change that produces matter with a different composition than the original matter.
What does this drawing represent?
Is this a compound, or element or mixture of both?
Answer: both compounds and elements
Unnumbered Figure, pg. 9
Investigating Chemistry, 2nd Edition
© 2009 W.H. Freeman & Company
Identify each of the containers as containing either elements, compounds, or both
Unnumbered Figure, pg. 9
Investigating Chemistry, 2nd Edition
© 2009 W.H. Freeman & Company
Identify each of the containers as containing either elements, compounds, or both
Answers:Elements: bCompounds: a, d, eBoth compounds and elements: c
Classifying matter
Mixtures
Is every sample taken the same?
No Yes
Heterogeneous Homogenous*Every sample is different *Every sample is the same*Usually easy to separate * Called “Solution”
Solute Solvent What gets dissolved Usually water
Copyright © Cengage Learning. All rights reserved
Have variable composition.
Mixtures
Homogeneous Mixture
Heterogeneous Mixture
Having visibly indistinguishable parts; solution.
Having visibly distinguishable parts.
Describing Matter Properties used to describe matter
can be classified as:
1) Extensive – depends on the amount of matter in the sample
- Mass, volume, calories are examples
2) Intensive – depends on the type of matter, not the amount present
- Hardness, Density, Boiling Point
Properties are…Words that describe matter (adjectives)Physical Properties- a property that can
be observed and measured without changing the material’s composition.
Examples- color, hardness, m.p., b.p.Chemical Properties- a property that
can only be observed by changing the composition of the material.
Examples- ability to burn, decompose, ferment, react with, etc.
Physical Properties Chemical Properties
Temperature AmountColor OdorMelting point SolubilityElectrical conductivity Hardness
Rusting (of iron) Combustion (of coal) Tarnishing (of silver) Hardening (of cement)
Some Examples of Physical and Chemical Properties
Properties of CompoundsQuite different properties than their
component elements.Due to a CHEMICAL CHANGE, the
resulting compound has new and different properties:• Table sugar – carbon, hydrogen,
oxygen• Sodium chloride – sodium, chlorine• Water – hydrogen, oxygen
States Of MatterLiquids:
Indefinite shape, definite
volume
Take the shape of container
Particles are close
together, but mobile
Particles move slowly
States Of MatterGases:
Indefinite shape
Indefinite volume
Take the shape and volume of container
Particles are far apart
Particles move fast
States Of MatterPlasma: Energized gases
Do not have a fixed volume. They are mostly empty space and can be compressed.
Do not have a fixed shape. They tend to fill the entire container.
States Of MatterHow do we change states of matter?
It requires energy.
What does the energy do?
It makes the molecules move. This causes friction, which results in heat being generated
38
Learning Check S1
Match: (1) solid, (2) liquid, or (3) gas.
____ A. Has a definite volume, but shape of the container.
____ B. Its particles are moving rapidly.
____ C. Fills the volume of a container.
____ D. Particles are in a fixed structure.
____ E. Particles are close together, but mobile.
39
Solution S1
Match: (1) solid, (2) liquid, or (3) gas.
_2_ A. Has a definite volume, but shape of the container.
_3_ B. Its particles are moving rapidly.
_3_ C. Fills the volume of a container.
_1_ D. Particles are in a fixed structure.
_2_ E. Particles are close together, but mobile.
Physical vs Chemical Properties
Properties are - Words that describe matter (adjectives)
Physical Properties- a property that can be observed and measured without changing the material’s composition.
Examples- color, hardness, m.p., b.p.Chemical Properties- a property that can
only be observed by changing the composition of the material.
Examples- ability to burn, decompose, ferment, react with, etc.
Physical vs. Chemical ChangePhysical change will change the visible
appearance, without changing the composition of the material.Boil, melt, cut, bend, split, crack Is boiled water still water?
Can be reversible, or irreversibleChemical change - a change where a
new form of matter is formed.Rust, burn, decompose, ferment
Copyright © Cengage Learning. All rights reserved
Change in the form of a substance, not in its chemical composition. Example: boiling or freezing water
Can be used to separate a mixture into pure compounds, but it will not break compounds into elements. Distillation Filtration Chromatography
Physical Change
It’s a physical change ifIt changes shape or size
It dissolvesIt changes phase (freezes, boils, evaporates, condenses)
What kind of change is it if someone...
Tears up paper?Physical changeMixes salt and water?Physical change
What kind of change is it if someone...
Burns paper?Chemical changeEvaporates salt water?Physical change
Chemical ChangeA change in which one or more substances are converted into different substances.
Heat and
light are often evidence of a chemical change.
Chemical ChangesThe ability of a substance to undergo
a specific chemical change is called a chemical property.• iron plus oxygen forms rust, so the
ability to rust is a chemical property of iron
During a chemical change (also called chemical reaction), the composition of matter always changes.
Recognizing Chemical Changes1) Energy is absorbed or released
(temperature changes hotter or colder)
2) Color changes
3) Gas production (bubbling, fizzing, or odor change; smoke)
4) formation of a precipitate - a solid that separates from solution (won’t dissolve)
5) Irreversibility - not easily reversed
But, there are examples of these that are not chemical – boiling water bubbles, etc.