Chapter 3
Atomic structure
Student check
In your own words what do you think the
“Big Bang Theory” is?

Structure of the Atom
There are two regions
1. The nucleus
protons and neutrons
Positive charge/ protons
Almost all the mass is found in the
Nucleus
2. Electron cloud- Most of the volume of
an atom
The region where the electron can be
found

Counting the Pieces
Atomic Number = number of protons
 # of protons determines kind of atom
 the same as the number of electrons in
the neutral atom
 Mass Number = the number of protons
+ neutrons
 All the things with mass

Student

What do you know about the atom?

What do you know about the nucleus?
Isotopes
Dalton was wrong.
 Atoms of the same element can have
different numbers of neutrons
 different mass numbers
 called isotopes

Student

What is the mass number?

What two parts of the atom make up
most of the mass of an atom?
Symbols

Contain the symbol of the element, the
mass number and the atomic number
Symbols

Contain the symbol of the element, the
mass number and the atomic number
Mass
number
Atomic
number
X
Symbols

Find the
– number of protons 9
– number of neutrons 10
– number of electrons 9
– Atomic number 9
– Mass Number 19
19
9
F
Symbols
 Find
the
–number of protons 35
–number of neutrons45
80
–number of electrons 35
35
–Atomic number 35
–Mass Number 80
Br
Student

How do you know the number of
protons of any given element?

What is the difference between the
atomic number and the mass number?
Symbols
 if
an element has an atomic
number of 34 and a mass number
of 78 what is the
–number of protons
–number of neutrons
–number of electrons
–Complete symbol
Symbols
 if
an element has an atomic
number of 34 and a mass number
of 78 what is the
–number of protons 34
–number of neutrons 44
–number of electrons 34
–Complete symbol Se
Symbols
 if
an element has 91 protons and
140 neutrons what is the
–Atomic number
–Mass number
–number of electrons
–Complete symbol
Symbols
 if
an element has 91 protons and
140 neutrons what is the
–Atomic number 91
–Mass number 231
–number of electrons 91
–Complete symbol Pa
Symbols
 if
an element has 78 electrons and
117 neutrons what is the
–Atomic number
–Mass number
–number of protons
–Complete symbol
Symbols
 if
an element has 78 electrons and
117 neutrons what is the
–Atomic number 78
–Mass number 195
–number of protons 78
–Complete symbol Pt
Naming Isotopes
Put the mass number after the name of
the element
 carbon- 12
 carbon -14
 uranium-235

Student

What is the.
– Atomic number
– Mass number
– number of protons
– Complete symbol


What is an isotope?
What questions do you still have?
Tutorial
Click on the arrorw to go to a tutorial on
mass number
 Atomic number
 Isotopes
 Electrons, Protons And Neutrons |
Standard Model Of Particle Physics
 Advanced
