What is Chemistry
Pages 38-44
Chemistry is
• the study of matter and its properties
Matter
• anything that has mass and takes up space.
Classification of Matter
Pure Substances
• have a fixed composition
• have definite properties
• there are 2 types of pure substances
1. Element
• substance that cannot be broken into a simpler substance
• contains only one type of atom
• Carbon (C), Oxygen (O), Nitrogen (N)
• Found on the Periodic Table of Elements
2. Compound
• Substances made of 2 or more different types of atoms.
• Molecule – a chemical combination of a fixed ratio of atoms
• Carbon dioxide ( CO2 )
• Water ( H2O )
• Table salt ( NaCl )
Mixtures
• A combination of 2 or more substances, that are not
chemically combined.
• Can be combined in any ratio
• Can occur between different phases of matter
• Soda – gas and liquid
• Salt water – solid and liquid
• Can occur between the same phase of matter
• Solids – metallic alloys, peas and carrots
• Liquids – Mio in water
• Gases – Air
2 types of mixtures
1. Homogeneous mixtures
• mixed uniformly throughout
• Kool aid
• Salt water
• Stainless steel
• Homogenized milk
2. Heterogeneous mixtures
• not uniformly mixed
• Italian dressing
• Dirt
• Ice water
Properties of Matter
Pages 45 – 52
There are 2 types of properties.
1. Physical properties
• properties that can be directly observed or measured
2. Chemical properties
• the property of a substance as to how it reacts or fails to react with
other substances.
Physical Properties – can be observed or measured.
Observations
Measurement
• Color
• Boiling point
• Odor
• Hardness
• State of matter
• Melting point
• Taste
• Conductivity
• Texture
• Density
Density
• is a physical property
• is a ratio between the mass and volume of an object.
• the unit for density is either g/cm3 or g/ml
• the formula for density is Density = Mass / Volume
If 10 cm3 of ice has a mass of 9.17g, what is the density of ice?
m = 9.17 g
Density = Mass/Volume
v = 10 cm3
D = 9.17 g/ 10.0 cm3
d = .917 g/cm3
A piece of tin has a mass of 16.52 g and a volume of 2.26 cm3. What is the density of
tin?
m = 16.52 g
Density = Mass/Volume
v = 2.26 cm3
D = 16.52 g/ 2.26 cm3
d = 7.13 g/cm3
A man has a 50.0 cm3 bottle completely filled with 163 g of a slimy green liquid.
What is the density of the liquid?
m = 163g
Density = Mass/Volume
v = 50 cm3
D = 163 g/ 50 cm3
d = 3.26 g/cm3
Create equations to solve for other variables of the density equation
Mass = Density x Volume
Volume = Mass/Density
Mass
Density
Mass
Volume
A piece of metal has a density of 11.3 g/cm3 and a volume of 6.7 cm3. What is the
mass of this piece of metal?
m = 76 g
Mass = Density x Volume
v = 6.7cm3
Mass = 11.3 g/cm3 x 6.7cm3
d = 11.3 g/cm3
The density of a piece of brass is 8.4 g/cm3. If the mass of the brass is 520 g, find the
volume of the brass.
m = 520 g
Volume = Mass/Density
v = 61.9 cm3
Volume = 520 g/8.4 g/cm3
d = 8.4 g/cm3
2. Chemical Properties
• The property of a substance as to how it reacts or fails to react with
other substances.
• Flammability
Substance
Helium
• Reactivity
Physical Property
Less dense than air
Chemical Property
Not flammable
White Powder
Reacts with vinegar
White Powder
Does not react with
vinegar
Colorless liquid
Flammable
Water
Colorless liquid
Non flammable
Iron
Malleable
Rusts in the presence of
oxygen
Baking Soda
Powdered Sugar
Rubbing Alcohol
Changes of Matter
Pages 53-58
Changes of matter fall under 2 categories
1. Physical Changes
• A change that does not change what the substance is.
• melting ice
• chopping wood
• cutting hair
• shredding paper
• Separating mixtures is a physical change
• picking pepperoni off a pizza
• separating the colors in a box of crayons
• Solutions are mixtures that take place at the molecular level. They
separated by physical means.
• Saltwater – water evaporates, and salt is left behind.
• Filtration – separation based on solubility
• Distillation – separation based on boiling point
• Skimming – separation based on density
2. Chemical Changes
• A change that causes a substance to form a new substance.
• Cannot be reversed by a physical change.
• burning sugar
• rusting iron
• baking a cake
• digestion
• Can break compounds down into elements