Transcript Intro to Chemistry

Introduction to Chemistry
Mrs. Ferry
www.unit5.org/chemistry
Job Skills for the Future
 Evaluate and Analyze
 Think Critically
 Solve Math Problems
 Organize and Use References
 Synthesize Ideas
 Apply Ideas to New Areas
 Be Creative
 Make Decisions with Incomplete Information
 Communicate in Many Modes
Chemistry will develop ALL of these skills in YOU!
Unit 1 – Chemistry Basics
Here we go!
Chemistry is the study of matter
and the transformations it can
undergo…
Chemistry
with a
Purpose
Areas of Chemistry
 Organic
The study of most carbon-containing compounds
 Inorganic
The study of all substances not classified as organic,
mainly those compounds that do not contain carbon
 Analytical
The identification of the components and composition of
materials
 Physical
The study of the properties, changes, and relationships between
energy and matter
 Biochemistry
The study of substances and processes occurring in living things
The Scientific Method
1- OBSERVE a phenomenon/ Ask a question
2- Form a HYPOTHESIS about it
3- EXPERIMENT to test hypothesis
4- Collect DATA and OBSERVATIONS
5- Draw a CONCLUSION
Using the scientific method requires that one
be a good observer.
observation
uses the five
senses
inference
involves a judgment
or assumption
“My mother the eye doctor”
Observation or Inference?
The
Names
The piece
player
players
adult
mother
of are
player
theof
iswritten
holding
teams
isin
the
holding
of
paper
holding
awearing
the
the
catcher.
umpire.
ispicture
batter
ison
the
called
aaapiece
note
bat
bat.
isare
uniforms.
the
isan
from
oftalking.
on
“Reds.”
paper.
optometrist
opposite
the
mother
teams.
orofopthalmologist
the batter. (an eye doctor).
One
athe
catcher’s
mask.
Hypotheses
 A tentative explanation for the observations
 May not be correct, but it puts the scientist’s
understanding of the system being studied into a
form that can be tested
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
1.2 Scientific Method
 Experiment
 Set of controlled observations
 Independent variable – the variable that will be changed.
 Dependant variable – the value that changes when the independent
variable changes.
 Constants – the other factors that are not allowed to change.
 Control – standard used for comparison
1.2 Scientific Method
 Experiment continued
 An experiment is designed to test the hypothesis that
table salt will dissolve faster in hot water than in
room temperature water.
 Independent variable:
temperature
 Dependant variable:
rate of dissolving
 Constants:
amount of salt, water, and stirring
 Control:
rate room temp water dissolves
Data
 Observations are also called data.
There are two types of data.
qualitative data
descriptions;
no numbers
quantitative data
measurements;
must have numbers
and UNITS
Scientific Law vs.
Scientific Theory
A law states what happens.
 Law of Gravity
A theory tries to explain why
or how something happens.
Theory of Evolution
Atomic Theory
States of Matter: Solid, Liquid, Gas
(a) Particles in solid
Def. Shape & Vol.
(b) Particles in liquid
(c) Particles in gas
Indef. Shape, Def. Vol.
Indef. Shape & Vol.
Some Properties of Solids, Liquids, and Gases
Property
Solid
Liquid
Gas
Shape
Has definite shape
Takes the shape of
the container
Volume
Has a definite volume
Has a definite volume
Arrangement of
Particles
Fixed, very close
Random, close
Random, far apart
Strong
Essentially none
Interactions between
particles
Very strong
Takes the shape
of its container
Fills the volume of
the container
Properties of Matter
 Physical property – quality of a substance that can be
observed without changing the substances composition
Name some physical properties!
Properties of Matter
 Two Types of Physical Properties
– Extensive properties –
dependent upon the amount of
substance present.
• Mass, volume, and length
– Intensive properties –
independent of the amount of
substance present.
• density
Properties of Matter
 Chemical property – The ability of a substance to undergo
chemical reactions and to form a new substance
 Ex. Rusting is a chemical properties of iron
 Other ex: rotting, decomposing, fermenting, corroding,
growing, decaying.
Physical and Chemical Properties
Examples of Physical Properties
Boiling point
Color
Slipperiness
Electrical conductivity
Melting point
Taste
Odor
Dissolves in water
Shininess (luster)
Softness Ductility
Viscosity (resistance to flow)
Volatility
HardnessMalleability
Density (mass / volume ratio)
Examples of Chemical Properties
Burns in air
Reacts with certain acids
Decomposes when heated
Explodes
Reacts with certain metals
Reacts with certain nonmetals
Tarnishes
Reacts with water
Is toxic
Ralph A. Burns, Fundamentals of Chemistry 1999, page 23
Chemical properties can ONLY be observed during a chemical reaction!
Changes in Matter
 Physical change – change that
results in a dramatically different
appearance yet leave the
composition of the substance
unchanged.
 Crumpling of a sheet of aluminum
foil.
 Changes in state
Changes in Matter
 Chemical change – of a process where one or more
other substances change into new substances.
 Starting Substances = Reactants
 New Substances = Products
 How do you know if it’s a chemical change has occurred?
1.Color change
• Solid or liquid precipitate
2.Odor or gas produced.
3.Light or energy involved.
Physical & Chemical Changes
CO2
crushing
heating
Pyrex
PHYSICAL
CHANGE
Limestone,
CaCO3
CHEMICAL
CHANGE
CaO
Crushed limestone,
CaCO3
Lime and
carbon dioxide,
CaO + CO2
The formation of a
compound
The formation of a
mixture
Sunlight
energy
O2
Pyrex
H2O2
Pyrex
H2O
Light hastens the decomposition of hydrogen peroxide, H2O2.
The dark bottle in which hydrogen peroxide is usually stored
keeps out the light, thus protecting the H2O2 from decomposition.
H
H
O
O
Chemistry Basics
Chemical vs. Physical Change
Memory Tool…
Vs.
Elements & Compounds
 ELEMENTS: the simplest forms of matter that can exist
under normal laboratory conditions
 Cannot be separated into simpler substances
 Building blocks for all other substances
 COMPOUNDS: Substances that can be separated into
simpler substances only by chemical reactions.
 Elements are always present in specific proportions
 Every element and compounds has its own unique set of
properties.
Chemical Symbols
 Each element is represented by a chemical symbol.
 The first letter is always capitalized
 If a second letter is used, it must be lowercase.
Groups of Elements
1A
1
H
1
2
3
Be
3
4
7
2A
Alkaline earth metals
6A
Oxygen group
Transition metals
7A
Halogens
3A
Boron group
8A
Noble gases
4A
Carbon group
8A
He
3A 4A
B C
5A 6A 7A 2
N O F Ne
Hydrogen
Inner transition metals
5
6
7
8
9
10
Al
Si
P
S
Cl
Ar
8B
K
3B 4B 5B 6B 7B
1B 2B 13 14 15 16 17
Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
12
20
21
22
Rb Sr
Y
Zr Nb Mo Tc Ru Rh Pd Ag Cd
In
39
40
41
42
49
Hf
Ta
W
72
73
74
37
6
Nitrogen group
Na Mg
19
5
5A
2A
Li
11
4
1A Alkali metals
38
Cs Ba
55
56
Fr
Ra
87
88
*
W
La
57
W
24
25
43
26
44
Re Os
75
76
27
28
29
47
30
45
46
Ir
Pt Au Hg
Tl
77
78
81
79
48
31
80
32
33
34
Sn Sb Te
50
51
Pb Bi
82
83
52
Kr
35
36
I
Xe
53
54
Po At Rn
84
85
86
Rf Db Sg Bh Hs Mt
104
*
23
18
Ac
89
105
106
107
108
109
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
58
59
60
Th Pa
U
90
92
91
61
62
63
64
65
66
Np Pu Am Cm Bk Cf
93
94
95
96
97
98
67
68
69
70
71
Es Fm Md No Lr
99
100
101
102
103
Mixtures of Matter
Classifying Mixtures
 Mixture – physical blend of two or more substances.
 Can be separated
 Substances are not present in specific ratios
1. Heterogeneous mixture – nonuniform composition.
2. Homogeneous mixture (solution) – uniform composition.
Mixtures of Matter
Separating Mixtures
Distillation – uses differences in boiling points to separate liquid-solid or
liquid-liquid mixtures.
Mixtures of Matter
Separating Mixtures
 Filtration – separate by passing through a barrier
Changes in Matter
 Conservation of Mass
 Law of conservation of mass – in an
ordinary chemical or physical reaction,
mass can’t be created or destroyed.
mass reactants = mass products
Changes in Matter
Changes in Matter
A reaction between sodium hydroxide and hydrogen
chloride gas produces sodium chloride and water. A reaction
of 22.85 g of sodium hydroxide22.85
with 20.82
g of hydrogen
g
20.82ggof water. What mass of sodium
chloride gives off 10.29
10.29 gin the reaction?
chloride is formed
sodium hydroxide + hydrogen chloride  sodium chloride + water
22.85 g + 20.82 g = sodium chloride + 10.29 g
43.67 g = sodium chloride + 10.29 g
33.38 g sodium chloride
Changes in Matter
 A reaction between sodium hydroxide and 19.87 g
hydrochloric acid produces water and sodium chloride. If I
end up with 7.54 g of water and 35.29g of sodium chloride,
how much sodium hydroxide did I start with?