chemistry wilbraham staley matta waterman chapter 2: introduction to chemistry & matter and...

ChemistryWilbraham

StaleyMatta

Waterman

Chapter 2:Introduction to Chemistry

& Matter and Change

Copyright © 2005 Pearson Education & Prentice-Hall, Inc.

Chemistry

The study of the composition of matter and the changes that matter undergoes.

Living and nonliving things are made of matter, chemistry affects all aspects of life

and most natural events.

creatures survive deep in the ocean where there is no light

why some foods taste sweet

some bitter

even why there is different shampoos for dry or oily hair.

chemical changes that occur in leaves can cause...?

The reason why...

Areas of study

organic chemistry

inorganic chemistry

biochemistry

analytical chemistry

physical chemistry

Organic Chem

The study of all chemicals containing carbon.

Athletes inhale chemicals developed by organic chemist to control symptoms of asthma.

Inorganic Chem

the study of chemistry that does not contain carbon.

non-living

example: inorganic chemist might explain how lacking calcium can affect the growth and repair of bones.

NOTE: there are other ways of getting calcium than drinking milk

Biochem

the study of the processes that take place in organisms.

example: how the energy used from the contraction of muscles is produced and stored.

Analytical chem

the area of study that focuses on the composition of matter.

example: measuring the level of lead in water

Physical chem

area that deals with mechanism; rate and energy transfer that occur when matter undergoes a change.

example: breathing during exercise.

Everything is a chemical

http://www.untamedscience.com/year-of-chemistry/july.php

Matter and Change

Properties of Matter

Describing matter

Extensive properties

Intensive properties

Extensive Properties

Matter is anything that has mass and takes up space.

Mass of an object is a measure of the amount of matter the object contains.

Volume of an object is a measure of the space occupied by the object.

Mass and volume are examples or extensive properties.

Extensive property depends on the amount of matter in a sample.

Intensive Property

Hardness is an example of intensive property.

Intensive property depends on the type of matter in a sample, not the amount of matter.

Identifying Substances

Substance: matter that has a uniform and definite composition.

Gold and copper are examples of pure substances.

Identifying Substances

physical properties: a quality or condition of a substance that can be observed or measured without changing the substance’s composition.

State, color, melting point, boiling point are all physical properties.

States of Matter

Three states of matter:

Solid

Liquid

Gas

plus plasma

Solids

Definite shape

Definite volume

Not easily compressed

particles are packed closely together in a rigid arrangement

Liquids

Indefinite shape

Definite volume

Not easily compressed

particles are close together, but free to flow past one another.

Gas

Indefinite shape

Indefinite volume

Easily compressed

particles are relatively far apart and can move freely.

Plasmais a state of matter similar to gas in which a certain portion of the particles are ionized.

Heating a gas may ionize its molecules or atoms (reduce or increase the number of electrons in them), thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions.

Lighting is an example of plasma present on the Earth’s surface

Checking In On a piece of paper answer the following from page 42 2.1 Section Assessment:

Name two categories used to classify properties of matter.

Explain why all samples of a given substance have the same intensive properties.

Name three main states of matter.

Describe the two categories used to classify physical changes.

Which property is Table 2.1 can most easily distinguish sodium chloride from the other solids?

In what way are liquids and gases alike? In what way are liquids and solids different?

2.2 Mixtures

How can mixtures be classified?

Mixture: is a physical blend of two or more components.

examples: chicken noodle soup, liquid salad dressing and air are all types of mixtures.

Based on the distribution of their components, mixtures can be classified as heterogeneous mixtures or as homogeneous mixtures.

Heterogeneous Mixture

Think about chicken noodle soup...

the ingredients are not evenly distributed throughout the mixture.

More chicken or noodles in one spoon full than the next.

Heterogeneous mixture: A mixture in which the composition is not uniform throughout.

Homogeneous Mixture

Think about olive oil and vinegar...

olive oil does not like a mixture, nor does vinegar.

Vinegar is a mixture of water and acetic acid, which dissolves in water.

Olive oil and vinegar are homogeneous mixtures.

Homogeneous mixture: is a mixture in which the composition is uniform throughout.

Another name is a solution.

Solutions

Many solutions are liquids.

Some gases, like air.

Some solids, like stainless steel- a mixture of iron, chromium and nickel.

Phase

Phase: is a term used to describe any part of a sample with uniform composition and properties.

Homogeneous mixture- consists of a single phase.

Heterogeneous mixture- consists of two or more phases.

Separating Mixtures

On a piece of paper write down how you would separate these mixtures:

In a salad

In a olive oil and vinegar mixture

and what might be a helpful tool?

In a salad you can remove ingredients you do not like (solid mixture).

In a olive oil and vinegar mixture- decant, or pour off, the oil layer- oil floats on water.

cool liquids till oil turns solid- oil freezes before vinegar.

taking advantage of the differences in physical properties to separate mixtures.

Filtration

Filtration: is a process that separates a solid from the liquid in a heterogenous mixture.

A colander can separate cooked pasta from the cooking water.

The holes, or pours, in a coffee filter are small enough so the coffee can not go through but not small enough to retain the particles of water.

DistillationDistillation: a liquid is boiled to produce a vapor that is then condensed into a liquid.

tap water is a homogeneous mixture of water and substances that dissolved in the water. One way to separate water from the other components in tap water is through distillation.

2.2 Section Assessment

Answer Q’s!

Elements and Compounds

Element: the simplest form of matter that has a unique set of properties.

Examples: Oxygen and hydrogen

Compound

Compound: is a substance that contains two of more elements chemically combined in a fixed proportion.

carbon, oxygen, and hydrogen are chemically combined in the compound sucrose.

Can compounds can be broken down into simpler substances?

Can elements?

Yes, compounds can be broken down into simpler substances by chemical means.

Elements cannot!

Chemical change: is a change that produces matter with a different composition than the original matter.

example: heating is one of the processes used to break down compounds into simpler substances.

Breaking down compounds

Properties of Compounds

Properties of compounds are quite different from those of their component elements.

Example: Sugar is a sweet-tasting, white solid.

Carbon is black, tasteless solid.

Hydrogen is a gas that burns in the presence of oxygen- a colorless gas that supports burning. The product hydrogen and oxygen is water, which stops materials from burning.

NaCl or sodium chloride

sodium and chloride

sodium is soft, gray metal

chlorine is a pale yellow-green poisonous gas

sodium chloride is a white solid

there is a change in the composition and a change

in properties.

If the composition of a material is fixed, the material is a substance.

If the composition of a material may vary, the material is a mixture.

What is the key difference between a substance and a solution?

The composition of a substance is fixed; the composition of a solution may vary.

Substance vs. solution

Symbols

Symbols are used to represent elements, and chemical formulas to represent compounds.

Each element is represented by a one- or two-letter chemical symbol.

The first letter- always capitalized.

Second letter- is lowercase.

Periodic Table

Periodic table: is an arrangement of elements in which the elements are separated into groups based on a set of repeating properties.

Allows you to easily compare the properties of one element (or group of elements) to another element (or group of elements).

Each element:

is identified by its symbol placed in a square.

listed in order from left to right and top to bottom by atomic number, a number that is unique to each element.

Shown centered above the symbol.

the lightest element hydrogen (H), is in the top left corner.

Each horizontal row of periodic table is called a period.

There are seven periods in the periodic table.

Within a period, the properties of the elements vary as you move across the period.

This pattern of properties repeat as you move to the next period.

Each vertical column of the periodic table is called a group or family.

Elements within a group have similar chemical and physical properties.

Each group is identified by a number and the letter A or B.

How many elements are in period 2?

In group 2A?

On a piece of paper, answer the following:

How many?

How many elements are in period 2? 8 elements

In group 2A? 6 elements

2.3 Section Assessment

Answer Q’s!

2.4 Chemical Reaction

Chemical changes

What happens during a chemical change?