Honors Chemistry Chapter 2 Notes Matter and Change

Honors Chemistry Chapter 2 Notes – Matter and Change

(Student edition)

Chapter 2 problem set:35, 37, 41, 46, 49, 54, 56, 60-63, 67, 71, 72, 76, 79, 80

Useful diagrams: 2.3, 2.8, 2.11

2.1 Properties of Matter

Matter: Anything that has and takes up . It is everything except .

Matter and energy are related in the equation:

Describing Matter: Properties are used to describe matter.

Mass: is a measure of the quantity of .

Weight: is a measure of the attraction of an object.

Volume: is a measure of the occupied by the object.

Properties - Characteristics of a substance which help to identify it.

Two questions: What can be observed? How does it behave with other substances?

Intensive Properties: of the size of the sample.

Examples:

Density: density is a ______ratio.

It involves a unit.

Which is heavier: a pound of feathers or a pound of lead?

They are the same weight; however, they have different densities.

Density changes with . Gases are affected than liquids or solids.

Extensive Properties: of the sample size.

Example:

Identifying Substances:

Physical Property: a quantity or condition of a substance that can be observed or

measured the substance’s composition.

States of Matter:

There are 4 phases of matter, but 3 main phases we deal with in chemistry.

solid ( ), liquid ( ), and gas ( )

Solid: a form of matter that has a shape and volume.

Liquid: a form of matter that has an shape, flows, yet has a fixed volume.

Gases: a form of matter that takes both the shape and volume of its container.

Plasma: high energy gas where escape from the atoms (occurs on the sun).

2.3Elements and Compounds (pure substances)

Element: A substance that can not be broken down by ordinary chemical reaction

(extraordinary - ).

Compound: When two or more elements are combined.

Molecule: The smallest particle of a compound that can exist on its own.

usually, molecules are assumed to be compounds, but...

Some elements can exist as atoms, some elements can exist only as molecules….

Monatomic Molecules: an atom, but also a molecule. Examples:

Diatomic Molecules:

Polyatomic Molecules:

Constant Composition: When every in a substance is exactly the same. Elements and compounds have constant composition. The word homogeneous can also be used to describe elements and compounds since every is the same.

Symbols of the Elements: sometimes, the Latin name is the source of a chemical symbol.

- ferrum - cuprum - plumbum

- natrium - stannum - aurum

- wolfram originally (German) - now it stands for

some elements are named after , some after

2.2Mixtures

Mixtures: two or more substance that are combined, each of which retains its own . It can be element-element, compound-compound, etc.

Mixtures are classified based on the distribution of their components.

Homogeneous Mixture (AKA ):

This mixture is transparent and evenly mixed. Salt water is an example of a solution. Every sample is the same; however, they do not have constant composition. Constant composition is where every particle is the same.

Heterogeneous Mixture (AKA ): This mixture shows (visible, distinct parts of the mixture). It is not evenly mixed. Example: olive garden salad.

2.3Continued …

Distinguishing Substances and Mixtures:

Types of Mechanical Mixtures: suspensions, emulsions, and colloidal dispersions

(colloids).

Mechanical mixtures exhibit the effect. This is the reflection of light off of particles big enough to reflect light. An example is dust in the projection light at movie theaters.

A comparison of solutions and mechanical mixtures:

It is commonly thought that all solutions are liquid based, but that is not true.

Brass: solid, solid solution

Air: gaseous solution

Aqueous (aq):

The classification of matter chart:

2.2Continued …

Separating Mixtures: differences in physical properties can be used to separate mixtures.

Filtration: The process that separates a solidfrom a liquid in a heterogeneous mixture.

Distillation: The process that separates a liquid out of a liquid-liquid mixture by boiling

the mixture to produce a vapor that is then condensed back into a liquid.

2.4Chemical Reactions

Chemical and Physical Properties:

Physical Property: a property that can be observed without changing the

substance into a new substance.

Examples:

Chemical property: a property that can be observed when changing the substance

into a new substance (or properties that describe how a substance

interacts or doesn’t interact with other substances).

Examples: see chemical changes

Chemical and Physical Change:

Chemical Change: a change when the substance turns into another substance by

losing, gaining, or rearranging atoms.

Examples:

A chemical change is a chemical reaction. Reactants are the substances at

the start of the reaction. Products are the substances produced in the reaction.

Physical Change: when a substance changes form, but not its identity or

chemical properties.

Examples:

Physical changes can be classified as reversible or irreversible.

The signs of a chemical change are:

Precipitates:

physical changes occur with a change in energy.

chemical changes involve some energy change although those changes may not be easily detected (some are small and some are great).

Conservation of Mass:

In the late 1700’s, it was known:

metal heat calx

(light)(heavy)

So .... it was thought that a change in mass is the result of a chemical change.

But.... Antoine Lavoisier (France) did the same experiment in a sealed container.

He found no change in mass.

Law of Conservation of Mass:

Extraordinary reaction: (of course, this was not known at the time).

Example:

NIBRelative Abundance

Lone Elements: state elements.

Combined Elements: combined state elements.

Most elements are found in the in nature.

Examples of free state elements:

Oxygen is the most common element on Earth. It makes up % of the earth’s crust, % (by weight) of the earth’s water, and % (by weight) of the earth’satmosphere.

Silicon makes up % of the earth’s crust.

The next six most abundant are:

The remaining elements make up less than % of the earth.

In living things the most abundant elements are:

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