The Structure of Matter and the Chemical

ElementsTextbook: Baker

Solids, liquids, and gases

Section 2.1

A model is a simplified approximation of reality.◦ Architects build models before the actual

construction◦ Business owners build models

Science models are simplified but, useful as a representation of what the structure will be like◦ Models are not always physical entities◦ Some could simply be a set of ideas

Model

All matter is composed of tiny Particles These Particles are in constant motion The amount of motion is related to

temperature. Increased temperature represents increased motion

Solids, gases, and liquids differ in the freedom of motion of their particles and in how strongly the particles attract each other.

States of Matter model

Particles of a solid can be pictured as tiny spheres held closely together

When a solid is heated, the average speed of the moving particles increases.

Faster-moving particles collide more violently, causing each particle to push its neighboring particle far away

Therefor the increase in temperature usually causes the solid to expand

Solids

Illustration

Particles in a liquid are still close together but, have more empty space between them than in a Solid

Liquids normally expand to fill a slightly larger volume

Attractions between them keep then a certain distance apart

Freedom of movement allows liquids to take the shape of their container

Liquids

Illustration

Particles of a gas are much father apart than a solid or liquid

According to the model each particle in a gas moves freely in a straight-line path until it collides with another particle

Particles are moving very fast and normally bounce off each other and continue on their own path

Gases

Illustration

The Chemical Elements

Section 2.2

Scientific Investigation◦ Are all the particles in a solid, liquid, or gas

identical?◦ What are the particles made of?

Materials◦ Glass of Water◦ Dissolved table salt

The Nature of Particles

1. Heating can separate the salt and water (Distillation)

◦ The water will evaporate thus, leaving the salt◦ Using the distillation apparatus water vapor will

be cooled and placed into a separate container

2. Run electric current through water and break down into Hydrogen gas and Oxygen Gas

3. Run electric current through melted dry salt and break down into Sodium metal and Chlorine gas

Breaking down substances

Salt water has been broken down into 4 elements or building blocks of matter◦ Elements –are substances that cannot be

chemically converted into simpler ones

Results

Water consist of ◦ Hydrogen ◦ Oxygen

Salt consist of◦ Sodium◦ Chlorine

These are both chemical compounds (covered in Chapter 3)

The mixture of the two are known as a solution (covered in Chapter 4)

Describing Common Elements

Illustration

There are current 114 elements◦ 24 are not naturally found on Earth

2-3 might exist in Stars◦ Some elements found in nature are Unstable

These elements exist for a limited time and then turn into other elements via radioactive decay

◦ Of the 83 stable elements found in nature, many are rare and will not be mentioned in this text

The Elements

Each element is known by name and a symbol

They are named in a variety of ways◦ The elements Francium and Californium were

named to honor the places where they were discovered.

◦ Some reflect the source from which the element was first isolated Hydrogen came from the Greek words water(hydro)-

forming(genes)◦ Some elements are named for their appearance

Idos means violet in Greek

Identifying Elements

Symbols are also chosen in a variety of ways◦ Some are the first letter of an elements name

C represents Carbon When two letters are used the first is capitalized the

second is lowercase Cl is chlorine and Co is cobalt

◦ Some symbols use the Latin names for the elements Na is sodium (Latin natrium) Au is gold (Latin aurum) means shining dawn

Most recent are not named yet are given temporary names and three letter symbols

Symbols

Common Elements

The Periodic TableSection 2.3

The Periodic Table

Arranged in groups or families that have similar characteristics◦ They are in columns◦ They are commonly referred to as Groups or

Families◦ Groups are numbered 1-18◦ Groups A or B

This convention is explained and illustrated better on the following slide

Structure of the Periodic Table

Groups A and B

Special Groups

Properties◦ Metals have a shiny metallic luster.◦ Metals conduct heat well and in the solid form

conduct electric currents.◦ Metals are malleable, which means they are

capable of being extended or shaped by the blows of a hammer.

Metals

Characteristics◦ Some are gases at room temperature and

pressure◦ Some are solids◦ Only one is a liquid◦ They do not have the characteristics listed

previously for metals

Non-metals

Characteristics◦ Have some but not all the characteristics of

metals Metalloids include:

◦ Boron◦ Silicon◦ Arsenic◦ Tellurium ◦ Astatine◦ Germanium◦ Antimony◦ Polonium

Metalloids

Illustrations

Room temperature (20) and normal pressure◦ Most elements are solid◦ Two are liquid (Hg and Br)◦ Eleven are has (H, N, O, F, Cl, and the noble

gases)

Elements

The Structure of the Elements

Section 2.4

The atom is the smallest part of the element that retains the chemical characteristics of the element itself.

An atomic mass unit (amu) is the mass of a carbon atom that has 6 protons, neutrons, and electrons

The Atom

Protons() have a positive 1+ charge Neutrons()have 0 charge Electrons() have a negative 1- charge Why a charge does?

◦ Opposite charge attract◦ Same charge repel

The Nucleus is the core and contains the protons and neutrons

Internal Structure

Illustration Review

Elements lose or gain electrons before the change the electrons have an equal number of and ◦ If it loses one or more it will have more , thus it

will have more positive charge and less minus charge, this ion becomes a cation.

◦ Inversely is there are loses one or more it will have more , then it will have an overall negative charge or anion

Ions

Cations and Anions

When an element has two or more atoms, each with the same number of protons but a different number of neutrons, the different species of element are called isotopes.

Isotopes

Atomic number is the number of protons in an uncharged atom

Atomic mass is the sum of protons and neutrons in an atom

*The Atomic number of an isotope is the same but, not the mass number because of the difference between the number of neutrons. To specify the different isotopes the mass number with follow the symbol for the element.

Atomic Number vs. Atomic Mass

19 of the elements found in nature have one occurring form. i.e. Al, aluminum atoms found in nature have 13 protons and 14 neutrons the mass is .

Naturally occurring forms

Sn or Tin atoms all have 50 , but Sn atoms can have:◦ 62, 64, 65, 66, 67, 68, 69, 70, 72 or 74 neutrons.

Thus tin has 10 natural isotopes for example:

Multiple Isotopes

Common ElementsSection 2.5

Covalent bond- the sharing of electrons

Molecules- uncharged collection of atoms

Hydrogen molecules contain two atoms; which make them Diatomic

Chemical Bonds

*Notice the prefix Di indicates there are two

Nitrogen Oxygen Fluorine Chlorine Bromine Iodine Hydrogen *Gases at room temperature

Other Diatomic Elements

Gaseous Diatomic Element

Liquid Diatomic Element

Solid Diatomic Element (Ball Stick)

Solid Diatomic Element (space-fill)

Each atom in a metallic solid has released an ◦ These atoms then become cations ◦ The free-moving electrons allow for them to be

good conductors of electric current More information is presented see “Sea-of-

electron” model

Metallic Elements

Sea-of-Electron Model

For review assignment Click Here

Review