Transcript Matter and Change Chapter 3 Diatomic  Two atoms of the same element bonded together.

Matter and Change
Chapter 3
Diatomic
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Two atoms of the same element bonded
together
Phase
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A sample of matter that looks the same
Substance
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A form of matter that has a uniform and
unchanging composition…aka a pure
substance
The 3 Physical States of Matter
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Solid
Liquid
Gas
Solid
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Definite shape and volume
Atoms/molecules held rigidly in place
Non-compressible
Liquid
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No definite shape; takes the shape of its
container; Non-compressible
Definite volume
Molecules are farther apart than those of a solid,
allowing molecules to flow past one another
Gas
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No definite shape nor volume
Gases take the shape & volume of their container
Gases are mostly empty space
Compressible
What is the physical state of each of
the following at room temperature?
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gold
gasoline
helium
bromine
lithium
nitrogen
The 3 Chemical Classes of Matter
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Element
Compound
Mixture
1. Element
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A substance that can’t be reduced to a
simpler form
The building blocks of all substances
Made up of only one type of atom
3 Types of Elements
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Metals: to the left of the “stair-step;” the
majority of the elements
Non-metals: to the right of the “stair-step”
Metalloids: non-metals on the stair step
having metal and non-metal properties
2. COMPOUNDS
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formed when 2 or more different elements
join chemically in a definite pattern/
arrangement
Can be made or separated by chemical
reactions
2 Types of Compounds
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ionic compounds: made up of a metal and a
non-metal portion
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covalent compounds: composed of nonmetals
Which of these are elements and
which of these are compounds?
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Hg
NaCl
O2
H2O
S8
3. Mixtures
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2 or more distinct substances mixed
together with variable composition
may have distinct phases
can be separated by physical methods
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Distillation
Filtration
chromotography
2 Types of Mixtures
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Homogeneous
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Heterogeneous
Homogeneous Mixture:
aka Solution (sol’n)
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Has a constant composition throughout
always has a single phase
can be any state of matter
Give me some examples of solutions
in each of the 3 states of matter.
gas: Air
nitrous oxide(dentist)
liquid: salt water
7-up
solid: gold ring, metal alloys
Heterogeneous Mixture
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A mixture that does not blend smoothly
throughout
2 or more distinct phases are visible
What are some examples of a
heterogeneous mixture?
Which of the 3 are substances?
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Elements
Compounds
Mixtures
Classify each of the following as
elements, compounds, or mixtures.
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Silver
pine tree
Carbon dioxide
orange juice
oxygen
iced tea
air
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water
Separating Mixtures
1.
2.
3.
4.
Filtration
Distillation
Crystallization
Chromatography
1. Filtration
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Filtration: a technique that uses a porous
barrier to separate a solid from a liquid.
Separates heterogeneous mixtures of
solids and liquids
Filtration
2. Distillation
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A separation technique that is based on
differences in the boiling points of the
substances involved
A mixture is heated until the substance with
the lowest boiling point boils to a vapor that
can then be condensed into a liquid and
collected.
Distillation
3. Crystallization
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A separation technique that results in the
formation of pure solid particles of a
substance from a solution containing the
dissolved substance.
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ie. Rock candy
Crystallization
4. Chromatography
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A technique that separates the components
of a mixture based on the tendency of each
to travel across the surface of another
material.
Chromatography
Physical Properties of Matter
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Physical properties are characteristics that can be
observed or measured without changing the
sample’s composition
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intensive properties: are independent of sample size.
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ie. density, color, boiling point
extensive properties are dependent on the amount of
material present.
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ie. mass and volume
Physical Changes of Matter
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Changes that alter a substance without
changing its chemical composition
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ie. Changes in physical state
Sublimation: solid to gas phase
For example: Dry ice
Boiling: liquid to gas
How can you change the physical
appearance without changing the state
Chemical Properties of Matter
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Chemical properties are only observed in
chemical reactions
Reactivity: the tendency of a substance to
undergo a particular chemical reaction
when exposed to an agent.
Examples
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2H2O reactivity to electric current→ 2H2(g) + O2(g)
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H2O reactivity to alkali metals→ H2(g)
[Cesium in water causes explosion]
Fe reactivity to O2 + H2O (fog)→ Fe2O3(rust)
Iron Oxide
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(you leave your bike out in the fog and it rusts)
Rubidium,Cesium, & Francium in water
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http://www.youtube.com/watch?v=jJGqC4v
XBms
Chemical Change
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A process that involves one or more
substances changing into new substances
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Reactants: the starting materials in a
chemical reaction
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Products: the newly formed substances
from a chemical reaction
4 Indicators of Chemical Change:
(often accompany chemical change)
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color change
precipitate formation
gas evolution
heat evolution or heat absorption
2 Types of Reactions
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Exothermic: Heat is released/given off
during a chemical reaction
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Endothermic: Heat is absorbed during the
chemical reaction
DEMOS:
Examples of Chemical Change
Gas Formation
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Zn + 2 HCl → H2 (g) + ZnCl2
Color Change and
Precipitate Formation
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2 KI + Pb(NO3)2 → 2 KNO3 + PbI2 (s)
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http://www.youtube.com/watch?v=REdFN7U91M&feature=player_detailpage
Conservation of Mass
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In a chemical reaction, matter is neither
created nor destroyed, but it can change
from one form to another.
Mass of Reactants= Mass of Products
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→ Material Balance
Conservation of Mass
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From a lab experiment designed to
separate water into hydrogen and oxygen,
a student collected 10.0 g of hydrogen and
79.4 g of oxygen. How many grams of
water were originally present?
Chemistry
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is the study of the composition of
substances and the changes they undergo.
In chemistry, a specific language is used
when referring to elements.
What do you notice about the letters
on the periodic table?
Periodic Table of Elements
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Groups: (Families) the vertical columns on the periodic table.
Periods: Horizontal Rows.
Each element is represented by a symbol
Symbols are one to three letters
The first letter is always capitalized, 2nd & 3rd letters are always
lower case.
Often the chemical symbols coincide with the spelling of the
element, but other times the symbols were derived from the
Latin name for the element.
Periodic Table of Elements, cont.
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Metals: Good conductors of heat and
electricity. In general, they are malleable,
ductile, lustrous, etc
Non-Metals: Poor conductors of heat and
electricity. Solids are brittle
Metalloid: Having characteristics of both
metals and non-metals
Chemical symbols
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Can be used to represent chemical
formulas.
The numerical subscripts tell the
proportion of each element in a compound
or diatomic element.
Tell me how many of each type of
atom are in the following:
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NaCl
CO2
HF
H2
ZnCl2
IUPAC
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International
Union (of)
Pure &
Applied
Chemistry
IUPAC-developed a systematic way of naming
elements that are 1st synthesized
One-syllable root word to represent
numbers
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0-nil
1-un
2-bi
3-tri
4-quad
5-pent
6-hex
7-sept
8-oct
9-enn
To write the name for synthesized
elements:
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Use the root word for each number in the
element
Add –ium to the ending
Examples
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110→…
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124 →…
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139 →....
To write the chemical symbol for the
element:
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Take the 1st letter of each root word,
capitalize it and lower case the 2nd and 3rd
examples
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113 →
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156 →
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213 →
Law of Definite Proportions:
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States that regardless of the amount, a
compound is always composed of the
same elements in the same proportion, by
mass.
For example, water, is always H2O…
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Which is ~11% Hydrogen
And ~89% oxygen
Percent by mass (%):
mass of element x 100
Mass of compound
Mass of Compound:
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the sum of the masses of the individual
elements that make up the compound.
Example
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A sample of an unknown compound
contains 5.3 g oxygen and 20.0 g of
copper. What is the percent by mass of
each element in the compound?
Law of Multiple Proportions
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States that when different compounds are
formed by a combination of the same
elements, different masses of one element
combine with the same relative mass of the
other element in a ratio of small whole
numbers
Ratios:
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Compare the relative amounts of any items
or substances
Express the relationship of elements in a
compound
Mass Ratio
1.
Mass of element in a compound = ratio
Mass of other element in compound
2. Mass ratio compound I = small whole #
Mass ratio compound II
*find the mass ratio for each compound, then divide
the two ratios to give a small whole # ratio
Example: Analysis Data of Two Iron Compounds
Are Compounds I and II the same compound?
If not, use the law of multiple proportions to show
the relationship between them.
Compound
I
II
Total
Mass
75.00
56.00
Mass Mass O
Fe (g)
(g)
52.46 22.54
43.53 12.47
Mass
% Fe
69.95
77.73
Mass
%O
30.05
22.27
Example cont.