Welcome to Chemistry!!. What is Chemistry? The study of all substances – composition, structure...

Welcome to Chemistry!!

What is Chemistry?

• The study of all substances – composition, structure and properties - and the changes that they can undergo.

• Chemistry is everything!!

Branches of Chemistry

CHEMISTRY

Organic Inorganic Biological PhysicalAnalytical Theoretical

Types of Research• Basic – for the sake of increasing

knowledge

• Applied – generally used to solve a problem

• Technological Development – production/use of products to improve quality of life

What is Matter?

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

• Mass is the amount of matter in an object.

Building Blocks of Matter

• Atom – smallest unit of an element that maintains the chemical identity of that element

• Element – pure substance, all one type of atom

• Compound – made of atoms of two or more elements chemically bonded

Properties

• Extensive – depend on amount of matter– Ex: volume, mass

• Intensive – do not depend on amount of matter– Ex: melting and boiling point, density

Physical Properties

• Physical Property- a property that can be observed and measured without changing the substance.

• Physical change - changes appearances, without changing the composition.

States of Matter

• Solid- has definite shape and definite volume.

• Liquid- definite volume but takes the shape of its container (flows).

• Gas- a substance without definite volume or shape and can flow.

• Plasma- high temperature state of matter where atoms lose most of their electrons

Solid

Liquid

Gas

Definite Volume?

YES

YES

NO

Definite Shape?

YES

NO

NO

Temp. increase

Small Expans.

Small Expans.

Large Expans.

Com-pressible?

NO

NO

YES

States of Matter

Solid Liquid Gas

Melt Evaporate

CondenseFreeze

Chemical Properties• Chemical Property- a property that can

only be observed by changing the type of substance.

• Examples: Flammability, decomposition, reactivity

• Chemical change/reaction - a change where a new form of matter is formed.

Chemical Reactions

• Reactants: substances that react

• Products: substances that are formed

Paper + Oxygen + Fire Ash + Smoke

Classification of Matter

MATTER

Can it be separated?

Mixtures Pure Substances

Is composition uniform? Can it be decomposed by ordinary chemical means?

Homogeneous Mixture

Air, sugar water, stainless steel

Heterogeneous Mixture

Granite, wood, blood

Compounds

Water, sodium chloride

Elements

Gold, aluminum

yes

yesyes

no

nono

Mixtures• Blend of two or more kinds of matter, each

of which retains its own identity and properties

• Heterogeneous- mixture is not the same from place to place.– Chocolate chip cookie, gravel, soil.– VISIBLE particles

• Homogeneous- same composition throughout. aka: solution– Kool-aid, air.– NON-VISIBLE particles

Separating Mixtures

• Heterogeneous mixtures use filtration or vaporization

• Homogeneous CANNOT use filtration

- use distillation, crystallization and chromatography

Distillation

Chromatography

Pure Substances

• Either Compounds or Elements

• Every sample has exactly same characteristic properties (mixtures depend on components)

• Every sample has exactly same composition ALWAYS

Which is it?

ElementCompoundMixture

MATTER

Can it be separated?

Mixtures Pure Substances

Is composition uniform? Can it be decomposed by ordinary chemical means?

Homogeneous Mixture

Air, sugar water, stainless steel

Heterogeneous Mixture

Granite, wood, blood

Compounds

Water, sodium chloride

Elements

Gold, aluminum

yes

yesyes

no

nono

Elements

Periodic Table

• Elements are organized into groups based on similar chemical properties

• Vertical columns – Groups/Families

• Horizontal rows – Periods

• 2 rows on the bottom– Lanthanide series– Actinide series

Types of Elements

Mr. Green. Mr. Green’s Homepage. 10 Sept. 2003. http://www.tvgreen.com/index.htm. 22 Aug. 2004

Metals

Metals

• Conduct electricity and heat

• Malleable: hammered into sheets

• Ductile: drawn into wire

• Tensile strength: resist breaking when pulled

Mr. Green. Mr. Green’s Homepage. 10 Sept. 2003. http://www.tvgreen.com/index.htm. 22 Aug. 2004

Nonmetals

Mr. Green. Mr. Green’s Homepage. 10 Sept. 2003. http://www.tvgreen.com/index.htm. 22 Aug. 2004

Metalloids

Types of Elements

• Nonmetals– Poor conductor of heat and electricity– Solids are brittle

• Metalloid– Share characteristics of metals and

nonmetals– semiconductors

• Noble Gases – relatively unreactive