Matter and Change

badwaterreflectiveUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

81 views

Matter and Change

Chapter 2

Substances

Matter

Mixtures

Elements

Homogeneous

Heterogeneous

Compounds

Elements, Compounds, and Mixtures


Pure substances

-

elements and compounds.


Elements

-

made of only one kind of atom.


Cannot be broken down into simpler
substances by normal chemical means.


Represented by symbols.


Normal symbols are 1 or 2 letters.


1st letter capital; 2nd letter lowercase.


Most

elements' symbols come from their
names.


Some elements with strange symbols:

Elements, Compounds, and Mixtures


Pure substances


Compounds

-

made of 2 or more diff. types
of atoms.


Atoms are combined in a fixed proportion.


Formula

-

shows the proportion of
atoms in a compound.

Elements vs Compounds

Mixtures


Mixture

-

combination of 2 or more
substances that are
not

chemically
combined.


Example: air (mix of oxygen, nitrogen, CO
2
,
H
2
O vapor, etc)


Example: stainless steel (mix of iron,
chromium, etc)


Mixtures can be separated by non
-
chemical means.

Types of Mixtures


Heterogeneous


Composition is not the same throughout.


Examples: chicken noodle soup; granite.


Homogeneous


Composition is same throughout.


Also called
solutions
.

Heterogeneous vs
Homogeneous

Pure
Substances

Heterogeneous
Mixture

Homogeneous
Mixture

Phases of Matter

Phase

Shape

Volume

Compression

Solid

Definite

Definite

Not easily
compressed

Liquid

Indefinite

Definite

Not easily
compressed

Gas

Indefinite

Indefinite

Easily
compressed

Describing Matter

Extensive Properties


Intensive Properties


Property that depends on
the amount of matter in a
sample


Examples


Mass


Volume


Property that depends on
the type of matter in a
sample


Examples


hardness

Properties of Matter

Physical

Chemical


Property that can be
observed without changing
the composition of the
substance


Examples


Color


density


The ability of a substance
to undergo a chemical
change


Example


The ability to rust


Flamability


Ability to react

Physical or Chemical Property?

1.
Blue Color

2.
Density

3.
Reacts with water to form a gas

4.
Melting Point

5.
Reacts with a base to form water


Changes of Matter

Physical



Chemical


Change where the
properties of the substance
may change but the
composition does not
change


Examples


Phase changes


Cutting and crushing


Change that produces
matter with a different
composition than the
original matter


Examples


Burning


Rusting

Physical or Chemical Change?

1.
Iron rusts.

2.
Wood rotting.

3.
A tire is inflated with air.

4.
Evaporation.

5.
Hydrochloric acid reacts with potassium
hydroxide to produce a salt, water, and
heat.

Separating Mixtures


Filtration


Separates a solid from the liquid in a
heterogeneous mixture


Distillation


Separates two liquids

Chemical Reactions


Aka chemical changes


Occurs when one or more substances
change into one or more new substances


Reactants


Products


Chemical Change Clues


Transfer of energy


Change in color


Production of a gas


Formation of a precipitate

Law of Conservation of Mass


Mass of reactants = Mass of products


Mass is neither created or destroyed, only
conserved.