Chapter 4 - Atomic structure
Lavoisier (1743-1794)
Helped turn_______________into an __________________________________
Verified the _________________________________________________________
Beheaded in ____________________________ Revolution (worked as a tax collector)- this pretty much stopped his career as a scientist
Early Models of the Atom
Democritus (a Greek Professor)
First suggested the existence of ______________________________________that make up____________
Named ____________
John Dalton (a scientist)
Studied the ratios in which ____________ combine in _________________________
Based his ideas on results of his __________________________________________
Dalton’s Atomic theory
All matter is composed of ___________________________called ___________________
Atoms do not change their________________________ when they undergo ___________________
Elements have only____________________________, all with the ______________________. Elements of different atoms are ___________________.
Compounds are composed of two or more elements combined in____________________________________.
Chemical reactions involve the __________________________ of atoms to give new______________________________. Atoms are not ____________________________________________.
Structure of the Atom
Discovered by__________________________ (Late 1890’s)
________________________ flowed through a ______________________________
Subatomic particles were attracted by a_________________charged plate – therefore, they had to be _____________
Even though atoms are _______________ ____________they contain definite negative charged particles, which we now know as _______________________________.
This led to a model of the atom known as the “__________________________”
Ernest Rutherford
Trying to find ___________________________to support the ________________________
“shot” _________________________________at a very thin layer of _____________________
Alpha particles (helium nuclei) have two relevant features here:
They have a lot of _____________________ (mass x speed)
Most alpha particles went ____________________________
Some were deflected off at _______________
Very few ______________________________________________(Rutherford this was as surprising as seeing a cannonball rebound from a sheet of tissue paper)
How to explain this (what could affect the positive alpha particle’s path sometimes but not often?)
They have a_______________________________
The Nuclear Atom
An atom with a __________________________of positive charge (_______________________) around which tiny electrons moved in a space that was otherwise empty
The nucleus contained positively charged ___________.
Neutron
Chadwick
Subatomic particle with slightly more _______ than a proton but has no ________
Subatomic Particles
Protons
charge is __________
location ___________
Neutrons
charge is __________
location ___________
Electrons
charge is __________
location ___________
Atomic Number
The number of ___________ in the nucleus of the atom
The atomic number identifies the element
Atoms are electrically neutral
# of __________ = # of __________
Mass Number
The total number of __________ and __________ in the nucleus of an atom
Interpreting Symbols
27
Al
13
Aluminum- 27
Sample Problems
How many protons, neutrons and electrons are in an atom of Be-9?
Protons = _____ Electrons = _____ Neutrons = _____
How many protons, neutrons and electrons are in an atom of Ne-20?
Protons= ______ Electrons= ______ Neutrons= ______
Ions
an atom or group of atoms that have a _________ or ________ charge
An ion has either gained or lost electrons
A positive ion has______ electron(s)
Called: ___________
A negative ion has ______ electron(s)
Called: ___________
Class work:
In your textbook complete the following questions:
Pg 111 #15 and 16
Pg 112 #17 and 18
Bohr Model
Niels Bohr
Sought to explain the ______________________________in more detail
Often called the_______________________________________
It is _______________(Atoms are not like little solar systems)
We can’t predict or know the exact _________________________ and________________ of an electron
# of Electrons in a Bohr Model
1st Energy level contains __________electrons
2nd Energy Level contains ________electrons
3rd Energy Level contains_________ electrons
4th Energy Level contains ________electrons
Draw Silicon:
Isotopes
atoms of the same element that differ in the number of _________________ in the nucleus
Because isotopes of an element have different numbers of neutrons, they have different __________ numbers.
Sample Problems
Two isotopes of carbon are carbon-12 and carbon-14. Write the symbol for each isotope using subscripts and superscripts. Determine the number of protons, neutrons and electrons for each isotope
Two isotopes of oxygen are oxygen-16 and oxygen-18. Write the symbol for each isotope using subscripts and superscripts. Determine the number of protons, neutrons and electrons for each isotope
Weighted Average Atomic Mass
Real-Life Application:
Calculate marking quarter grade:
Test 80
Quiz 90
HW 100
*What would the average be if all categories were weighted equally?
*What if the breakdown was as follows:
Tests 50%
Quiz 30%
HW 20%
Average Atomic Mass
Sample Problems
What is the atomic mass of silicon if 92.21% of its atoms have mass 27.977u, 4.70% have mass 28.976u and 3.09% have mass 29.974u?
Find the average atomic mass for silver if 51.83% of silver atoms have mass 106.905 and 48.17% of atoms have mass 108.905?