matter: properties and changes - norwell high school · 2014-10-10 · elements & compounds •...

Matter: Properties and Changes

Chapter 3.1: Properties of Matter

Substances

• Review:

• Matter is anything that has mass and takes up space.

• Matter with uniform and unchanging composition is pure substance.

• ie~ Table salt (NaCl)

• What about H2O? Pure water = yes; seawater / tap water = no.

Sates of Matter

• States of Matter

• All matter that exists can be classified into one of three forms:

• Each can be distinguished by the way it fills a container.

• Exception to rule: plasma (fourth state of matter)

• Found in lightning bolts and stars.

Chapter 3: Matter - Properties and

Changes

3.1 Properties of Matter

States of Matter

Solid -

Liquid -

Gas -

Vapor -

Physical Properties -

1

States of Matter

• Solid

• Definite shape and volume.

• Particles tightly packed.

• Expands slightly when heated.

States of Matter

• Liquid

• Flows and has constant volume.

• Particles not held in place and packed less closely.

• Able to move past one another.

• Takes shape of container.

• Expands when heated.


Changes


States of Matter

Solid -

Liquid -

Gas -

Vapor -


1

States of Matter

• Gas

• Flows to conform to shape of container & fills entire volume.

• Expands to fill containers.

• Particles are very far apart

• Easily compressible.


Changes


States of Matter

Solid -

Liquid -

Gas -

Vapor -


1

States of Matter

• Gases vs Vapor

• Do not mean the same thing!

• Gas is a substance that is naturally in the gaseous state at room temperature.

• Vapor refers to gaseous state of substance that is solid or liquid at room temperature

• Helium? Neon? Steam?

Physical Properties of Matter

• Characteristic that can be observed or measured without changing the composition.

• Also describe pure substances.

• Uniform and unchanging compositions = consistent and unchanging properties.

• Examples include: Density, color, odor, hardness, melting point, boiling point.

Chemical Properties -

3.2 Changes in Matter

Physical Change -

2


• Two Types

• Extensive

• Dependent on the amount of substance present.

• Examples include: Length, mass, & volume.


• Two Types

• Intensive

• Independent on the amount of substance present.

• Examples include: Density- always the same regardless of how much substance is present.

• Substances can be identified by intensive properties.

• ie~ scent

Chemical Properties of Matter

• The ability of a substance to combine with or change into one or more other substances.

• Composition of substance changes.

• Results from contact with other substances or addition of energy (thermal or electric).

• Example: Iron = Forms rust when in contact with oxygen in air

• Copper =



Physical Change -

2

Chemical Properties of Matter

• Each substance has its own unique set of physical and chemical properties.

• Copper: Can be shaped into different forms (physical) or turns green when in contact with air (chemical)



Physical Change -

2


Chapter 3.2: Changes in Matter

Changes in Matter

• Physical Change

• Changes in appearance but not composition.

• Examples include: 1) Cutting sheet of paper 2) Breaking glass object 3) Crumpling piece of aluminum foil

Changes in Matter

• Phase Change

• Transition of matter from one state to another.

• Depends on temperature and pressure of surroundings.

• As temperature and pressure change, substances change from one phase to another.

• Example is the water cycle:

• 1) Ice (solid) is heated to become liquid water. 2) Add more heat, liquid water boils and is converted to steam (gas).

• What type of changes are these? Physical (Different appearance but same composition)

Changes in Matter

• Phase Change

• Melting and Boiling Points

• The temperature and pressure at which a substance undergoes a phase change.

• Intensive physical properties that can be used to identify unknown substances.

Changes in Matter

• Chemical Change

• One or more substances changing into new substances.

• aka~ chemical reaction

• New substances formed have different compositions and properties.

Changes in Matter

• Chemical Reaction

• Starting substances = reactants.

• New substances formed = products.

Changes in Matter

• Chemical Reaction

• Evidence includes a change in properties.

• ie~ spoiled food: What are some changes in properties? Look, taste, digestability...

Chemical change -

Evidence of Chemical Change

Law of Conservation of Mass -

A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of Magnesium

oxide. How many grams of oxygen reacted?

3

Changes in Matter

• Law of Conservation of Mass

• Mass is neither created nor destroyed during a chemical reaction.

• It is conserved.

• mass of reactants = mass of products.

• Although chemical changes occur, total mass remains constant.

Changes in Matter

• Law of Conservation of Mass

• Mass is neither created nor destroyed during a chemical reaction.

Chemical change -

Evidence of Chemical Change

Law of Conservation of Mass -

A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of Magnesium

oxide. How many grams of oxygen reacted?

3


Chapter 3.3: Mixtures of Matter

Changes in Matter

• Most everyday matter occurs as mixtures.

• Combination of two or more pure substances.

• Each pure substance retains its individual chemical properties.

• Composition of mixtures is variable.

Changes in Matter

• Types of Mixtures

• Heterogeneous

• Mixture that does not blend smoothly.

• Composition is not uniform.

• Substances remain distinct.

• Examples include: salad dressing, orange juice, etc.

Changes in Matter

• Types of Mixtures

• Homogeneous

• Has constant composition throughout.

• Always has single phase.

• Referred to as solutions.

Changes in Matter

• Solutions

• Most familiar with liquid forms.

• Examples include: tea, lemonade, etc

• Solution systems can be solid, liquid, or gas.

• Solid-solid solutions of metals are known as alloys.

• Examples include: steel, bronze, 14-karat gold.

Changes in Matter

• Solutions

3.3 Mixtures of matter

Mixture -

Heterogeneous Mixture -

Homogeneous Mixture (solution) -

4

Separating Mixtures

• Important to be able to separate mixtures to understand nature of matter.

• Use physical processes to separate mixtures based on physical properties.

• ie~ magnet to separate metal from sand.

Separating Mixtures-

Filtration -

Distillation -

5

Separating Mixtures

• Filtration

• Separates heterogeneous mixtures composed of solids and liquids.

• Uses a porous barrier.

Separating Mixtures-

Filtration -

Distillation -

5

Separating Mixtures

• Distillation

• Used to separate most homogeneous mixtures.

• Based on differences in boiling points.

1) Mixture is heated until lower boiling

point boils to vapor.

2) Vapor is condensed into liquid and

collected.

Separating Mixtures

• Crystallization

• Results in the formation of pure solid particles of a substance.

• Solid particles come from solution containing dissolved substance.

• Solids are highly pure

• Example: rock candy

Crystallization -

Sublimation -

6

Crystallization -

Sublimation -

6

Separating Mixtures

• Sublimation

• Solid changes to vapor without going through liquid phase.

• Used to separate one solid that sublimates form one that does not.

Chromatography -

3.4 Elements and Compounds

Element -

Periodic Table -

Compounds -

7

Separating Mixtures

• Chromatography

• Separates components of a liquid mixture (mobile phase) based on ability of each to travel across another material (stationary phase).

• Components flow through stationary phase at different speeds.


Chapter 3.4: Elements and Compounds

Elements & Compounds

• Matter can take many different forms.

• All matter can be broken down into basic building blocks called elements.

• Element is a pure substance that cannot be separated into simpler substances by physical or chemical means.

• 92 natural elements

• Several others that have been developed


• Elements have unique chemical names & symbols.

• Names consist of 1/2/3 letters.

• First ALWAYS capitalized; rest are lowercase.

• 92 natural elements not evenly distributed.

• H2: 75 % of mass of universe.

• O2, H2, C: 90% of human body

• Under normal conditions, elements can be found in each type of phase. (ie~ Cu, Hg, He)


• Elements organized into a periodic table.

• Based on similarities and masses

• Rows = periods

• Columns = groups / families

• Elements in same group have similar chemical and physical properties.


• Compounds made up of two or more different elements that are chemically combined.

• Most matter in the universe exists as compounds.

• 10 million known; ~ 100,000 developed each year.

• Chemical formulas of compounds

• Composed of chemical symbols and subscripts.

• Subscripts indicate number of elements in each compound.

• ie~ H2O, NaCl

Properties of Compounds vs. Elements

8


• Compounds can be broken down into simpler elements by chemical means.

• Compounds generally more stable than individual elements.

• Requires energy (ie~ heat or electricity).

• Electrolysis is breakdown of H2O.

*** What do you notice about the amount

of H2 compared to the amount of O2?


8

Properties of Compounds

• Properties of a compound are different from those of the individual elements.

• ie~ H2O

• How is H2O different than H2 & O2?


• Properties of a compound are different from those of the individual elements.


8

Law of Definite Proportions -

A 1.0 g sample of hydrogen reacts with 19.0 g of fluorine. What is

the % of hydrogen in the compound?

9

• Organization of Matter

• Pure substances & mixtures.

• Separation???


Law of Definite Proportions

• Elements in compounds combine in definite proportions by mass.

• Law of Definite Proportions = Compound is composed of same elements in the same proportion by mass.

• Mass of the compound = sum of masses of elements that make up the compound.




9


• Amounts of elements in a compound can be expressed as percent by mass.

• Ratio of the mass of each element to the total mass of the compound.




9


• Amounts of elements in a compound can be expressed as percent by mass.

• Ratio of the mass of each element to the total mass of the compound.

• Percent by mass the same regardless of amount of sucrose; each has the same mass proportion

Law of Multiple Proportions - When different compounds are

formed by a combination of the same elements, different mass of

one element combine with the same relative mass of the other

element in a ratio of small whole numbers

10

Law of Multiple Proportions

• Use when comparing different compounds composed of the same elements.

• Law of Multiple Proportions = Different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in a ratio of small whole numbers.

Law of Multiple Proportions

Law of Multiple Proportions - When different compounds are

formed by a combination of the same elements, different mass of

one element combine with the same relative mass of the other

element in a ratio of small whole numbers

10

mass ratio of Compound I mass ratio of Compound II = 1.793 g Cu / g Cl

0.8964 g Cu / g Cl = 2.000

• Mass ratio of copper to chlorine in Compound 1 is exactly two times the mass ratio of copper to chlorine in Compound II.

• 2:1

matter: properties and changes - norwell high school · 2014-10-10 · elements & compounds •...

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