Transcript unit-1-introduction

Introduction
to Chemistry
What Matters?
SI Units
•
•
•
•
•
•
Length – meter
Mass – kilogram
Time – second
Temperature – Kelvin
Quantity of Matter – mole
Volume - liter
Commonly Used Prefixes
• Centi- 1/100 or 0.01
• Kilo1000 or 1.0 x 103
• Milli1/1000 or 0.001
Matter
• Def- anything that has mass and
occupies space
• 3 States of matter
– Solid
– Liquid
– Gas
Phase Changes
•
•
•
•
•
•
Melting
Freezing
Vaporization/Evaporation
Condensing
Sublimation
Deposition
Changes of State
Melting/Freezing
• Energy must be ADDED for a
substance to melt
• Energy must be REMOVED for a
substance to freeze
Vaporization & Condensation
• Energy must be ADDED for a
substance to boil
• Energy must be REMOVED for a
substance to condense
Deposition/Sublimation
• Energy must be added for a
substance to sublime
• Energy must be removed for a
substance to undergo deposition
Law of Conservation of Energy
• Energy cannot be created or
destroyed
• Energy of a reaction MUST be
conserved
Elements, Compounds
& Mixtures
Elements
• An element is matter in its simplest
form
• Cannot be broken down by chemical
means
• Periodic Table (114 elements)
Compounds
• Are combinations of elements
• Have the same composition
• Can be broken down by chemical
means
Mixtures
• Have variable composition
• Can be separated physically or
chemically
• Homogeneous Mixtures – are the
same throughout
• Heterogeneous Mixtures – have
different regions
Law of Conservation of Matter
• Matter cannot be created or
destroyed
• Mass of a chemical reaction MUST be
conserved
Separatory Techniques
Filtration
• Used for separating undissolved
solids
• Pour through a mesh (filter paper)
Distillation
• Used to separate dissolved solids or
liquid mixtures
• Uses physical changes
Chromatography
• Uses chemicals to separate the
pigments of plant or chemicals
• Various Methods
– Gas chromatography
– Liquid chromatography
– Thin-layer chromatography
– Ion-exchange chromatography
Chemical vs Physical
Physical Properties
• A set of
characteristics
unique to a
substance
•
•
•
•
•
•
•
Odor
Color
Volume
State
Density
Boiling point
Melting point
Chemical Properties
• The ability of a
substance to form
new substances
•
•
•
•
Wood burning
Iron rusting
Digestion
photosynthesis
Physical Change
• Does NOT change the identity of the
substance
• Composition remains the same
Chemical Change
• Changes the composition of the
substance
• Has new physical properties that
differ from the original
Indicators of Chemical Change
• Formation of a gas (bubbles)
• Formation of a precipitate (solid)
• Change in temperature
– Exothermic
– Endothermic
• Color change
Properties
• Extensive Properties – depend on the
amount of substance present
– Volume
– Mass
– Energy present
• Intensive Properties – do NOT depend
on the amount of substance present
–
–
–
–
Melting point
Boiling point
Density
Conductivity
Solids, Liquids, and Gases
Solids – have both definite volume and
shape
Liquids – have definite volume but not
shape
Gases – have neither definite volume
or shape
Particles have increasing velocity from
solids to liquids to gases
Elements & The Periodic Table
Periods – horizontal rows
Groups – vertical columns
Group
Group
Group
Group
Group
Group
1A – alkalai metals
2A – alkalai earth metals
3A-12A – transition metals
16A – chalcogens
17A – halogens
18A – noble gases
The Periodic Table
Metals
•
•
•
•
Conduct heat and electricity
Malleable
Ductile
Luster (shiny)
Non-metals
•
•
•
•
Poor conductors of heat
Poor conductors of electricity
Many are gases at room temp
5 solid non-metals
– Phosphorous
– Sulfur
– Carbon
– Selenium
– iodine
Metalloids
Have some characteristics of both
metals and non-metals
Noble Gases
• Least reactive of all elements
• All gases at room temp