MatterMatter

Anything that has Anything that has massmass and takes up and takes up spacespace..

All matter can be measuredAll matter can be measured MassMass VolumeVolume DensityDensity

Hundreds of Hundreds of years ago, years ago, scientists found scientists found that certain that certain types of matter types of matter couldn’t be couldn’t be broken down into broken down into any other simpler any other simpler substancessubstances

They called these They called these special pure special pure substances: substances: elementselements

No matter how small you No matter how small you divide it, gold is only made of divide it, gold is only made of

gold atoms.gold atoms.

So what is an atom?So what is an atom? The smallest particle an element can The smallest particle an element can

be divided into and still maintain the be divided into and still maintain the properties of that element.properties of that element.

Atoms are the building blocks of all Atoms are the building blocks of all matter.matter.

Why learn about atoms?Why learn about atoms?All matter is made of atoms, atoms are the

basic building block of everything in the universe

What does an atom look What does an atom look like?like?

The model of the structure of the The model of the structure of the atom has changed as technology has atom has changed as technology has improved and as more evidence has improved and as more evidence has been gathered.been gathered.

HISTORY OF THE ATOM

460 BC

Democritus develops the idea of atoms

He pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he called

ATOMAATOMA

(greek for indivisible)

First atomic models – roughly First atomic models – roughly based on earth, air, water, and based on earth, air, water, and

firefire

HISTORY OF THE ATOM

1808

John Dalton

Suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them

ATOMATOMSS

The new model of an atom- a The new model of an atom- a tiny solid spheretiny solid sphere

HISTORY OF THE ATOMHISTORY OF THE ATOM

1898

Joseph John Thompson

found that atoms could sometimes eject a far smaller negative particle which he called an

ELECTRONELECTRON

Thompson develops the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron's charge

1904

like plums surrounded by

pudding.PLUM

PUDDING

MODEL

The new model of an atom- The new model of an atom- atoms contain smaller, atoms contain smaller,

negatively charged particles negatively charged particles

1910 Ernest Rutherford

• English scientist who tested JJ Thompson’s model • Rutherford’s new evidence allowed him to propose a more detailed model with a central nucleus. • He suggested that the positive charge was all in a central nucleus. This held the electrons in place by electrical attraction

Rutherford’s experimentRutherford’s experiment

The results?

His hypothesis:

The new atomic model- a The new atomic model- a dense, positively charged dense, positively charged

nucleus in the center nucleus in the center surrounded by electronssurrounded by electrons

1913

Niels Bohr

studied under Rutherford in Manchester, England

Bohr refined Rutherford's idea by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons.

Bohr’s Atom

electrons in orbits

nucleus

The new atomic model- The new atomic model- electrons are in orbits around electrons are in orbits around

the nucleus at different energy the nucleus at different energy levelslevels

1920’s1920’s

Electron Cloud ModelElectron Cloud Model Electrons surround the positively Electrons surround the positively

charged nucleus, but not in set charged nucleus, but not in set orbitsorbits

They are in different levels, or They are in different levels, or cloudsclouds

There are set amounts of electrons There are set amounts of electrons found in each cloudfound in each cloud

The new atomic model- set The new atomic model- set numbers of electrons are found numbers of electrons are found

in different cloud layersin different cloud layers

Atomic Model HistoryAtomic Model History

http://www.youtube.com/watch?http://www.youtube.com/watch?v=QbWKF9uDF7wv=QbWKF9uDF7w

https://www.youtube.com/watch?https://www.youtube.com/watch?v=thnDxFdkzZsv=thnDxFdkzZs

NeutronNeutron

The neutron was not discovered until The neutron was not discovered until 1932 when James Chadwick 1932 when James Chadwick

This new idea dramatically changed This new idea dramatically changed the picture of the atomthe picture of the atom

ATOMS AND ATOMIC ATOMS AND ATOMIC STRUCTURESTRUCTURE

Atom Nucleus Proton Neutron Atom Nucleus Proton Neutron Electron Electron

WHAT IS AN ATOM?WHAT IS AN ATOM?o The smallest unit The smallest unit

of an element.of an element.

o Consists of a Consists of a central nucleus central nucleus surrounded by surrounded by one or more one or more electrons.electrons.

WHAT IS THE NUCLEUS?WHAT IS THE NUCLEUS?o The central part The central part

of an atom.of an atom.o Composed of Composed of

protons and protons and neutrons.neutrons.

o Contains most of Contains most of an atom's mass.an atom's mass.

WHAT IS A PROTON?WHAT IS A PROTON?

o Positively Positively charged particle. charged particle.

o Found within an Found within an atomic nucleus.atomic nucleus.

WHAT IS A NEUTRON?WHAT IS A NEUTRON?

o Uncharged Uncharged particle. particle.

o Found within an Found within an atomic nucleus.atomic nucleus.

WHAT IS AN ELECTRON?WHAT IS AN ELECTRON?

o Negatively Negatively charged particle. charged particle.

o Located in shells Located in shells that surround an that surround an atom's nucleus. atom's nucleus.

SummarySummary

Particle ChargeParticle Charge Mass (amu) Mass (amu) LocationLocation

ProtonProton positive positive 1 1 nucleusnucleus

Neutron neutralNeutron neutral 1 1 nucleus nucleus

Electron negativeElectron negative < 1 < 1 shells shells

outside the outside the nucleusnucleus

Atoms are neutralAtoms are neutral

Since Since protonsprotons ( (positivepositive charge) charge) are equal to the numbers of are equal to the numbers of electronselectrons ( (negativenegative charge), the charge), the overall charge of an atom is overall charge of an atom is neutralneutral

Atomic number equals the number of ____________ or ___________.

Atomic mass equals the number of ______________ + ____________. (mass number)

Atoms as Pictured on the Periodic Table

Atomic NumberSymbolNameAtomic Mass

protons electrons

protons neutrons

Ion charged particle formed when an atom gains or loses an electron

Video of particlesVideo of particles

http://www.youtube.com/watch?v=lP57gEWcisY

Bill Nye http://www.youtube.com/watch?

v=aNK1mQfNeik

Let’s review Let’s review The Atomic Number of an atom = The Atomic Number of an atom =

number of ______________ in the number of ______________ in the nucleus. (Equal to nucleus. (Equal to electrons)

The Atomic Mass of an atom = The Atomic Mass of an atom = number of _________ _________ in number of _________ _________ in the nucleus.the nucleus.

The number of Protons = Number of The number of Protons = Number of ____________.____________.

_____________ orbit the nucleus._____________ orbit the nucleus.

Protons

Protons + neutrons

electrons

Electrons

Build an atomBuild an atom

http://phet.colorado.edu/en/http://phet.colorado.edu/en/simulation/build-an-atom simulation/build-an-atom

Atom arrangement Atom arrangement animationanimation

http://web.visionlearning.com/http://web.visionlearning.com/custom/chemistry/animations/custom/chemistry/animations/CHE1.3-an-animations.shtmlCHE1.3-an-animations.shtml

http://www.bbc.co.uk/newsround/http://www.bbc.co.uk/newsround/2236946822369468