Atomic Structure Models. The Ancient Model Greeks were first to consider the fundamental nature of matter. Cut something in half enough times eventually.

Atomic Structure Models

The Ancient ModelGreeks were first to consider

the fundamental nature of matter.

Cut something in half enough times

eventually it becomes a single uncuttable piece.

The ATOM (atomos = greek for “uncuttable”

JJ Thompson - The “Plum Pudding” model

Positive charge sphere (the pudding)

Studded with negative charge electrons (the raisins)

Used Cathode Ray Tubes and measured deflection of particles

The Cathode Ray Tube

Cathode Ray Tube

Ernest RutherfordDiscovered the Nucleus!

Alpha Particles shot at gold foil were expected to pass right through

Instead a small percentage of them were deflected!

This meant there had to be a concentration of mass at the center!

Rutherford

James ChadwickDiscovered the Neutron!

Beryllium was bombarded with radiation

It emitted particles with NO charge (neutral)

The final piece of the atomic puzzle… but was it all assembled correctly?

The Atom?

Today’s Quantum ModelThe electron “cloud” model

Electrons do not “orbit” the nucleus like planets

They have “regions of probability”

This is where electrons are LIKELY to be found.

They move too fast to observe continuously!

Grouping the Elements

Families on the Periodic TableElements on the periodic table have been

grouped into families based on their chemical properties.

Each family has a specific name to differentiate it from the other families in the periodic table.

Elements in each family react differently with other elements.

Basic classificationsMetals – Shiny, silver/grey/whitish, good

conductors, malleable, high melting pointsNonmetals – Dull, low melting points, poor

conductors, brittle, Metalloids – Not metals, but not nonmetals

either… properties of both!

shells

ALKALI METALSGroup 1Hydrogen is not a member, it

is a non-metal (but also a Metal)

1 electron in the outer shell

Soft and silvery metals

Very reactive, esp. with water

Conduct electricity

ALKALINE EARTH METALSGroup 22 electrons in the

outer shell

White and malleable

Reactive, but less than Alkali metals

Conduct electricity

TRANSITION METALSGroups in the

middle

Good conductors of heat and electricity.

Some are used for jewelry.

Can bond with many elements in a variety of shapes.

BORON FAMILY Group 33 electrons in

the outer shellMost are metalsBoron is a

metalloidAluminum is on

the metal/non-metal border, but is NOT a metalloid!

CARBON FAMILY Group 44 electrons in

the outer shell

Contains metals, metalloids, and a non-metal Carbon (C)

Si and Ge vital to the information age (computers)

NITROGEN FAMILY Group 55 electrons in

the outer shellEasily share

electrons to form compounds (N and P especially)

Contains metals, metalloids, and non-metals

OXYGEN FAMILY Group 66 electrons in

the outer shellContains

metals, metalloids, and non-metals

Reactive

HalogensGroup 7All are non-metals

(Astatine is a metalloid)

One electron away from full outer shells!

Very reactive are often bonded with elements from Group 1

Like NaCl (Table salt!)

Noble GasesGroup 8Exist as gases

Non-metals

Full Outer electron shells, they don’t want to share!

Not reactive with other elements

Rare Earth MetalsMany are

Radioactive

The rare earths are silver, silvery-white, or gray metals.

Conduct electricity

Large Nuclei!

Why not show it this way?What would be the difficulty with this?