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WHAT DO YOU THINK ATOMS WHAT DO YOU THINK ATOMS LOOK LIKE?LOOK LIKE?
• Draw what you think atoms look Draw what you think atoms look likelike
• Why do you think they look like Why do you think they look like this?this?
HISTORY OF THE ATOMHISTORY 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)
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
HISTORY OF THE ATOMHISTORY OF THE ATOM
1910 Ernest Rutherford
they fired Helium nuclei at a piece
of gold foil which was only a few
atoms thick.
they found that although most of
them passed through. About 1 in
10,000 hithttp://micro.magnet.fsu.edu/electromag/java/rutherford/
ATOMIC STRUCTUREATOMIC STRUCTURE
Particle
proton
neutron
electron
Charge
+ ve charge
-ve charge
No charge
1
1
nil
Mass
SIZE OF ATOMS ANALOGYSIZE OF ATOMS ANALOGY
Atom = Skydome, Toronto
Nucleus = baseball
Protons = marbles inside baseball
Electrons = mosquitoes buzzing around baseball
1. Draw a diagram showing the location of the three types of particles in an atom.
2. Name each type of atomic particle
3. Write the charge of each atomic particle
WHAT DO ATOMS LOOK LIKE?WHAT DO ATOMS LOOK LIKE?
http://daveovergaard.pbworks.com/w/page/50839329/What%20do%20atoms%20look%20like
ATOMIC STRUCTUREATOMIC STRUCTURE
= number of protons in an atom
= number of protons and neutrons in an atom
HeHe22
44 Atomic mass
Atomic number
number of electrons = number of protons
ATOMIC STRUCTUREATOMIC STRUCTURE
What is the atomic number of H (hydrogen)?
What is the atomic mass of H (hydrogen)?
How many electrons and protons are in hydrogen atoms?
What would it look like?
ATOMIC STRUCTUREATOMIC STRUCTURE
What is the atomic number of Li (lithium)?
What is the atomic mass of Li (lithium)?
How many electrons and protons are in lithium atoms?
What would it look like?
QUIZ QUESTION:QUIZ QUESTION:
1. Atomic mass is the number of __________ and ___________ in an atom
2. Atomic number is the number of ___________ in an atom
3. How many protons are in this atom?4. What is the overall charge of this atom?5. What element is this atom?
ATOMIC STRUCTUREATOMIC STRUCTURE
Electrons are arranged in Energy Levels
or Shells around the nucleus of an atom.
• first shell a maximum of 2 electrons
• second shell a maximum of 8
electrons
• third shell a maximum of 8
electrons
ATOMIC STRUCTUREATOMIC STRUCTURE
There are two ways to represent the atomic
structure of an element or compound;
1. Electronic Configuration
2. Dot & Cross Diagrams
ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION
With electronic configuration elements are
represented numerically by the number of
electrons in their shells and number of shells. For
example;
N
Nitrogen
7
14
2 in 1st shell
5 in 2nd shell
configuration = 2 , 5
2 + 5 = 7
ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION
Write the electronic configuration for the following elements;
Ca O
Cl Si
Na20
40
11
23
8
17
16
35
14
28B
11
5
a) b) c)
d) e) f)
2,8,8,2 2,8,1
2,8,7 2,8,4 2,3
2,6
DOT & CROSS DIAGRAMSDOT & CROSS DIAGRAMS
With Dot & Cross diagrams elements and
compounds are represented by Dots or Crosses to
show electrons, and circles to show the shells. For
example;
Nitrogen N XX X
X
XX
X
N7
14
DOT & CROSS DIAGRAMSDOT & CROSS DIAGRAMS
Draw the Dot & Cross diagrams for the following elements;
O Cl8 17
16 35a) b)
O
X
XX
X
X
X
X
X
Cl
X
X
X
X X
X
XX
X
X
X
X
X
XX
X
X
X
SUMMARYSUMMARY
1. The Atomic Number of an atom = number of
protons in the nucleus.
2. The Atomic Mass of an atom = number of
Protons + Neutrons in the nucleus.
3. The number of Protons = Number of Electrons.
4. Electrons orbit the nucleus in shells.
5. Each shell can only carry a set number of electrons.
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