ch11 lecture outline
TRANSCRIPT
Chapter 11: Investigating Matter
Principles of Science
This lecture will help you understand:
• Chemistry: The Central Science• The Submicroscopic World• The Phases of Matter• Physical and Chemical Properties• Determining Physical and Chemical Changes• Elements to Compounds• Naming Compounds
Chemistry: The Central Science
Chemistry is the study of matter and the transformations it can undergo.
Physics Biology
AstronomyEarth Science
Chemistry: The Central Science
Chemistry
Chemistry: The Central Science
• Chemistry is a "materials" science.– Most of the material items in any modern
house are shaped by some human-devised chemical process.
Chemistry: The Central Science
Chemistry: The Central Science
• More than 70% of all legislation placed before the U.S. Congress addresses science-related questions and issues.
The Submicroscopic World
• Roughly 250,000 dunes of this size contain about 125 million trillion grains of sand.
• Yet, that's how many atoms there are in a single grain of sand. (Atoms are small.)
What are atoms?
• Atoms are the smallest particles of matter • Atoms make up everything around us • Molecules are combinations of atoms • Elements are only one type of atom • Compounds are made up of different types of
atoms
The Phases of Matter
• One of the most evident ways we can describe matter is by its physical form, which may be one of three phases (also sometimes described as physical states):
• The gaseous phase of any material occupies significantly more volume than either its solid or liquid phase.
• Frozen carbon dioxide, CO2, "dry ice"
The Phases of Matter
GasGas
LiquidLiquidSolidSolid
DepositionDepositionSublimationSublimation
MeltingMelting
FreezingFreezing
CondensationCondensationEvaporationEvaporation
The Phases of Matter
Physical and Chemical Properties
• A physical property describes the look or feel of a substance.
Physical and Chemical Properties
• A chemical property describes the tendency of a substance to transform into a new substance.
It is a chemical property of iron to transform into rust.
Physical and Chemical Properties
Physical and Chemical Properties
A physical change is a change in the physical properties of a substance.
• Chemical properties are properties that characterize the ability of a substance to react with other substances or to transform from one substance into another.
Physical and Chemical Properties
• Any change in a substance that involves a rearrangement of the way atoms are bonded is called a chemical change.
Determining Physical and Chemical Changes
CarbondioxideCarbondioxideOxygenOxygen CarbonCarbon
Determining Physical and Chemical Changes
Determining Physical and Chemical Changes
• A physical change is a change in the physical properties of a substance.
• A chemical change is the transformation of one or more substances into others.– A substance is identified not only by the kinds
of atoms it contains but also by how those atoms are connected to one another.
– During a chemical change, a new substance is formed as atoms rearrange themselves into new configurations.
Determining Physical and Chemical Changes
• A physical change imposes a new set of conditions on the same material.
• A chemical change forms a new material that has its own unique set of physical properties.
• Both physical and chemical changes result in a change in physical appearance.
Potassiumchromate
Potassium chromate + Heat Potassiumchromate(cooled)
Determining Physical and Chemical Changes
• Physical or chemical change?
Physical or chemical change?
Ammoniumdichromate
Ammonium dichromate + Heat Ammonia,water,chromium(III) oxide
• An element is a material made of only one kind of atom. Pure gold is an element because it is made of only gold atoms.
• An atom is the fundamental unit of an element.
• The term "element" is used when referring to macroscopic quantities.
• The term "atom" is used when discussing the submicroscopic.
Elements to Compounds
Compound Formula
Oxygen O2
Ozone O3
Sulfur S8
Gold Au
Elements to Compounds
• The elemental formula is used to show the proportion by which atoms combine to form an element.
Elements to Compounds
A compound is a substancethat consists of atoms ofdifferent elements.
Elements to Compounds
• Compounds have properties uniquely different from the elements from which they are made.
Compound Formula
Sodium chloride NaCl
Ammonia NH3
Water H2O
Elements to Compounds
• A chemical formula is used to show the proportion by which elements combine to form a compound.
• Guideline 1– Start with the element farthest to the left in the
periodic table.– For the element to the right, add the suffix -ide.
Example:
NaCl
Naming Compounds
Sodium chloride
Example:
NaCl
Na Cl
Naming Compounds
Naming Compounds
• Guideline 2– With different possible combinations of
elements, use prefixes to remove ambiguity.
mono-
di-
tri-
tetra-
1
2
3
4
Naming Compounds
Examples:
CO carbon monoxide
CO2 carbon dioxide
Naming Compounds
Examples:
H2O dihydrogen monoxide
H2O2 dihydrogen dioxide
Naming Compounds
Examples:
H2O water
H2O2 hydrogen peroxide
Naming Compounds
Naming Compounds
• Guideline 3– Common names are sometimes used for
convenience.