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?