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