Early Theories
The relationship in which masses of elements can combine to form a particular ratio that can be reduced to small, whole numbers.
Law of Definite Proportions
He is associated with philosophical atomism
Democritus
Do neutrons have a charge and can they contribute to the overall charge of a particle?
NO
The first atomic model was created by this scientist?
John Dalton
In atomic notation, n stands for the number of
neutrons in an atom
Two isotopes of the same element have the same number of _______________ but a different number of _______________.
protons
neutrons
Matter was made of separate discrete particles
Atomism
He is responsible for the first atomic model
John Dalton
The number of protons an atom has is called
The atomic number
Describe JJ Thompson atomic model
Plum Pudding Model
--the pudding was the positively charged material
--the plums were the negatively charged material
In atomic notation, Z stands for the number of
protons in an atom
Isotopes generally have the same chemical properties but different _______________ properties.
physical
Those who believed that matter could be continuously subdivided believed in what theory
The continuous theory of matter
Joseph Proust
An electrically balanced atom must have the same number of what?
Protons and electrons.
Rutherford's model was changed to include the addition of ......
neutrons
The atomic number is represented by what symbol.
Z
Identifying different isotopes is important for understanding the risks associated with what?
Physical properties.
The two ancient philosophies regarding the science of matter
1) atomism
2) continuous theory of matter
JJ Thompson was responsible for identifying that every atom had small particles of what charge?
negative
The smallest particle capable of chemical interactions is the
atom
Rutherfolds model showed that the __________ of an atom is the smallest region in the center that is positively charged
nucleus
The atomic mass is represented by what symbol?
A
Besides H-1, what other isotopes of Hydrogen occur? Give their scientific names.
Dueterium: H-2
Tririum: H-3
The fact that any sample of salt contains 1 g of sodium (NA) and 1 gram of chlorine (CL) illustrates
The law of definite proportion.
He created a new atomic model because of what was discovered during the alpha particle experiment?
Ernest Rutherford
This is why the neutron was not detected for many years.
A neutron is electrically neutral, making it difficult to detect.
List the three major atomic particles from lightest to heaviest?
electron, proton, neutron
Weighted averages of isotopes of an element determine its
atomic mass
Tritium is an isotope of hydrogen. It has a mass number of 3. What is the isotopic notiation?
3
H
1
He worked with cathode rays
J.J. Thompson
He is responsible for identifying the neutron.
James Chadwick
Chemical and physical properties
One-twelfth of the mass of a C-12 is defined as
atomic mass unit
Write the isotopic notation for fifty-two protons, seventy-eight neutrons, and fifty-two electrons.
What is the element?
130
Te
52
Telliurium
Write the isotope notation for Chlorine with 17 protons and 20 neutrons.
37
CL
17
He experiemented with x-rays
Wilhelm Roetgen
He did the gold foil experiment.
Hans Geiger
He discovered protons
Rutherford
Draw a diagram of the models created by Dalton, Thompson, and Rutherford.
see the text book p 71, 81, 83
A naturally occurring sample of the element gallium (Ga) is a mixture of two isotopes. In a sample of gallium, 60.11% of the atoms have a mass of 68.9856u and 39.89% of the atoms have a mass of 70.9247u. Calculate the mass of gallium.
.6011 x 68.9856 = 41.43
.3989 x 70.9247 = 28.28
Mass of Gallium = 41.43 + 28.28
What is the isotopic notation for an atom that has 35 protons, 32 neutrons, and 35 electrons?
67
X
35