Properties of MatterProperties of Matter

O’Connor/chapter 4O’Connor/chapter 4

Physical vs Chemical Physical vs Chemical Property PropertyProperty Property

A property that A property that describes the describes the behavior of a behavior of a substance without substance without reference to any other reference to any other substancesubstance

A property that A property that describes the describes the behavior of a behavior of a substance when it substance when it reacts or combines reacts or combines with another with another substance.substance.

Typical Physical PropertiesTypical Physical Properties

WeightWeight

VolumeVolume

ColorColor

Boiling pointBoiling point

Melting pointMelting point

Things that can be measured without altering the Things that can be measured without altering the material’s composition through a chemical material’s composition through a chemical reaction.reaction.

Typical Examples of Chemical Typical Examples of Chemical PropertiesProperties

When wood burns it chemically combines When wood burns it chemically combines with oxygen in the air to create a new with oxygen in the air to create a new substance; this transformation describes a substance; this transformation describes a chemical property of wood.chemical property of wood.

A color transformation of heroin exposed to a A color transformation of heroin exposed to a chemical called Marquis reagent is to turn chemical called Marquis reagent is to turn purple, it allows for a simple test to confirm if purple, it allows for a simple test to confirm if a substance is heroin in a laboratory setting.a substance is heroin in a laboratory setting.

How are properties used in a lab?How are properties used in a lab?

Which properties forensic scientists Which properties forensic scientists choose to observe & measure depends on choose to observe & measure depends on the type of material that is being the type of material that is being examined.examined.

If a property can be assigned a numerical If a property can be assigned a numerical value, it must relate to a standard system value, it must relate to a standard system of measurement (metric) that is accepted of measurement (metric) that is accepted throughout the scientific community.throughout the scientific community.

Metric System (SI)Metric System (SI)

Devised in 1791 by the French Academy Devised in 1791 by the French Academy of Science.of Science.Uses a simple decimal relationship so that Uses a simple decimal relationship so that a unit of length, volume, or mass can be a unit of length, volume, or mass can be converted into a subunit by simply converted into a subunit by simply multiplying or dividing by a multiple of 10.multiplying or dividing by a multiple of 10.At times, it may be necessary to convert At times, it may be necessary to convert units from the metric system into the units from the metric system into the English system, or vice versa.English system, or vice versa.

Basic ConversionsBasic Conversions

1 inch1 inch == 2.54 centimeters2.54 centimeters

1 meter1 meter == 39.37 inches39.37 inches

1 pound 1 pound == 453.6 grams453.6 grams

1 liter1 liter == 1.06 quarts1.06 quarts

1 kilogram1 kilogram == 2.2 pounds2.2 pounds

The Nature of MatterThe Nature of Matter

Matter is anything that has mass & Matter is anything that has mass & occupies space.occupies space.

Atomic Theory and the discovery of Atomic Theory and the discovery of matter’s simplest identity the element lets matter’s simplest identity the element lets us understand the composition of all us understand the composition of all matter.matter.

ElementElement

Is a fundamental particle of matter that Is a fundamental particle of matter that cannot be broken down into a simpler cannot be broken down into a simpler substances by chemical means.substances by chemical means.

Elements provide the building blocks from Elements provide the building blocks from which all matter is composed. At present, which all matter is composed. At present, 118 elements have been identified, 89 118 elements have been identified, 89 occur naturally on Earth and the rest are occur naturally on Earth and the rest are created in a lab.created in a lab.

Periodic TablePeriodic Table

CompoundCompound

A pure substance composed of two or A pure substance composed of two or more elements.more elements.

When two or more elements are When two or more elements are combined. example Carbon Dioxidecombined. example Carbon Dioxide

Since there are 89 natural elements, there Since there are 89 natural elements, there are huge possibilities for combinations. are huge possibilities for combinations. More than 16 million known compounds More than 16 million known compounds have already been identified.have already been identified.

Compound cont.Compound cont.

An atom is the basic unit of an element, An atom is the basic unit of an element, the molecule is the smallest unit of a the molecule is the smallest unit of a compound.compound.

A molecule of NaCl (table salt) represents A molecule of NaCl (table salt) represents the combination of one atom of the the combination of one atom of the element sodium (Na) with one atom of the element sodium (Na) with one atom of the element chlorine (Cl).element chlorine (Cl).

States of MatterStates of Matter

Organizing what we find on Earth is Organizing what we find on Earth is complicated so we classify it by the complicated so we classify it by the physical form it takes.physical form it takes.

Physical States- solid, liquid, & gas (vapor)Physical States- solid, liquid, & gas (vapor)

Solid StateSolid State

Molecules in matter are held closely Molecules in matter are held closely together by strong attractive forces. This together by strong attractive forces. This molecular arrangement makes solid matter molecular arrangement makes solid matter rigid and gives it a definite shape and rigid and gives it a definite shape and volume.volume.

Liquid StateLiquid State

The attractive forces between molecules The attractive forces between molecules are weaker. are weaker.

The molecules are in contact with one The molecules are in contact with one another, but are not held as rigidly in another, but are not held as rigidly in place. place.

A liquid occupies a specific volume, but its A liquid occupies a specific volume, but its fluidity causes it to take the shape of the fluidity causes it to take the shape of the container in which it resides.container in which it resides.

GasGas

Attractive molecules are much weaker, Attractive molecules are much weaker, allowing them to move freely.allowing them to move freely.

Gaseous matter has neither a definite Gaseous matter has neither a definite shape nor volume, and it will completely fill shape nor volume, and it will completely fill any container into which it is placed.any container into which it is placed.

Changes of StateChanges of State

Substances can change form one state to another.Substances can change form one state to another.

Example:Example:

Water is heated to 100 C, water boils and rapidly Water is heated to 100 C, water boils and rapidly changes into steam. At 0 C, water solidifies or freezes changes into steam. At 0 C, water solidifies or freezes into ice. Under some conditions a solid can go directly into ice. Under some conditions a solid can go directly to a gaseous state. We call this sublimation~ steam off to a gaseous state. We call this sublimation~ steam off snow.snow.

No new chemical species was formed; matter simply No new chemical species was formed; matter simply changed state.changed state.http://www.harcourtschool.com/activity/states_of_matter/http://www.harcourtschool.com/activity/states_of_matter/

PhasesPhases

Whenever substances can be distinguished by a Whenever substances can be distinguished by a visible boundary, different phases are said to visible boundary, different phases are said to exist.exist.

• Oil floating on water is an example of a two- Oil floating on water is an example of a two- phase system. The oil & water each constitute phase system. The oil & water each constitute a separate liquid phase, clearly distinct from a separate liquid phase, clearly distinct from each other.each other.

• Forensic Scientists use the existence of Forensic Scientists use the existence of different phases to identify & classify evidence different phases to identify & classify evidence found at a crime scene.found at a crime scene.