Properties of Matter. Characteristics of a substance

Properties of Matter

Properties of Matter

• Characteristics of a substance

Physical Properties• characteristics that can be observed without

changing the chemical identity of the substance– Not dependent on amount of sample

AppearanceOdorMelting PointBoiling PointDensity

HardnessTextureDuctility/MalleabilitySolubilityElectrical/Thermal

ConductivityMagnetism

Chemical Properties• Characteristics that describe the ways a substance can

react to form new materials– Cannot be observed without changing the chemical

composition of the substance

• Examples

FlammabilityReaction with OxygenReaction with Water

Decomposition by lightDecomposition by heatTendency to Corrode

Physical Changes• Changes that do not result in the formation of

a new substance– Chemical bonds have not been broken or formed;

the molecules are still connected in the same way• Change of state• Change in appearance

Chemical Changes• Changes in the chemical bonds of a substance

– Always produce a new substance– Chemical bonds are broken and/or formed

– Signs:• Visible flame• Color change • Bubbling/Fizzing• Smoke• Heat/Light given off• Formation of a substance in a different state

Kinds of Matter• Elements

– cannot be broken down into any other substance– All matter is composed of elements.– Each element is made of a specific type of ATOM

• Ex: Oxygen

• Ex: Hydrogen

Kinds of Matter

• Compounds– two or more elements chemically combined in a

specific ratio

Kinds of Matter

• Mixtures– two substances that are together in the same

place but are NOT chemically combined

States of Matter• Matter is made of tiny particles that are in

constant, random motion– can be classified as a solid, liquid, gas, or plasma

depending on the motion and arrangement of the particles

Solid• Particles do not move freely, but vibrate in

place– Packed tightly together, usually arranged in a

specific & fixed pattern• Definite volume• Definite shape

Liquid• Particles move freely

– Fairly close together, but not in a fixed pattern• Definite volume• Indefinite shape (take shape of container)

– Viscosity: resistance to flow• High viscosity – slow flow (honey)• Low viscosity – easy flow (water)

Gas• Particles move very energetically in all

directions– Very fast and far apart

• Indefinite volume (take up all available space)• Indefinite shape (take shape of container)

Plasma• Particles have extremely high energy

– Highly energetic charged particles that move independently

– Extremely fast and far apart• Most of the matter in the universe!

Particle Motion• Solids – particles tend to move slowly (vibrate) and keep

their shape• Liquids – particles move freely and take the shape of

their container• Gasses – particles move excitedly and fill all available

space• Plasmas – charged particles move extremely excitedly

and fill all available spaceWhat misconceptions could be created by the model shown here of particles in a solid, liquid, gas, and plasma?

Phase Changes• Transfer of heat energy is

required to change the state (or phase) of a substance– Freezing/Melting Point– Boiling/Condensation Point

Argon Ice melting and sublimating at the same moment

Phase Graphs

Draw your own Phase Graph

Density• Density is a measure of how closely packed

the atoms are in a substance• Density will change as temperature changes

– As a substance is heated, particles tend to spread, making it less dense (ice is an exception)

– Solids tend to be more dense than liquids; liquids tend to be more dense than gasses.

Calculating Density• Density equals mass divided by volume• d = m/v

– Mass usually measured in grams (g)– Volume either found by displacement or calculated

using a formula (mL, cm3, or cc)• Units: g/mL or g/cm3 or g/cc

Sinking and Floating• Density determines whether an object will sink

or float.• Substances/Objects that are

more dense will sink in substances that are less dense.

• Substances/Objects that are less dense will float in substances that are more dense.– The diet coke is less dense than

water. The regular coke is more dense than water. • Coke = 1.042 g/mL Diet Coke = 0.997g/mL• Water = 1.000 g/mL

Conductivity• Electrical Conductivity – the ability of a substance to

allow electrical energy to flow through it• Thermal Conductivity – the ability of a substance to allow

thermal energy to flow through it– Both are related to density

• CONDUCTORS: more dense materials tend to be better conductors (allow energy to flow through them easily)

• INSULATORS: less dense materials tend to be poor conductors (resist the flow of energy through them)

Special Properties of Water• Unlike most substances, the freezing point and

boiling point of water allow it to exist as a solid, liquid, and gas at natural Earth temperatures

Special Properties of Water• Water heats up & cools down very slowly

compared to other substances– Due to a property called “specific heat”– This maintains a moderate environment on Earth that

is suitable for life

Special Properties of Water• Water forms “polar molecules”, creating “hydrogen

bonds” between molecules. This results in…– Cohesion – water molecules attracted to each other

– Adhesion – water molecules attracted to other substances

Special Properties of Water• Water is called the “universal solvent”

– Many other substances dissolve in water• The water we encounter is rarely pure because so many

minerals can easily dissolve in it.