Download Chemistry Notes (pg. # 1)

Chemistry Notes (pg. # 1)
Chemistry _ _
- Def: The study of all _________ and the ________ they
can undergo.
-The study of m________ and e________
The word “Chemistry” comes from the word “Alchemy”, and has its
roots in this “endeavor”.
Chemistry, the C________ science:
-Chemistry has been called the c________ science because
it o_________ so many other sciences.
Ex. Biology, physics, engineering, medicine
- Chemistry is considered the central science, and the idea of
the _________ is central to the central science.
Atomic Theory:
Question: What would happen if you were able to cut a piece of
aluminum foil over and over and over…Would you always still have
aluminum?
Democritus- G______ p_______ (450 B.C.) who proposed the idea of
atoms. He called them “_______”
- Democritus believed that atomos were small, i________
particles.
____________- The search for a general understanding of
reality by chiefly speculative rather than observational means.
- Limitation of _____________: Does not use
ex____________.
____________- systematic knowledge of the physical or material
world gained through observation and e_______________.
Limitation of ___________: Limited to information
gained through p_____________ e_____________.
- The ideas of Democritus were dismissed by his fellow
philosophers through the use of l_______; however,
the idea of the atom was re-visited by the s_________
John Dalton in the early 1800’s.
-
Modern View of The Atom:
The atom is composed of ________, _______, and ______.
Particle:
Mass:
1.0073 amu
1.0087 amu
0.0006 amu
Charge:
(+)
Location:
Question: How did scientists determine that the atom is made up of
____________, ____________, and ____________?
- Also, how did they determine that there is a
____________ and an electron “__________”?
Evidence for the Negative Electron:
Cathode Ray T_____ Experiment:
The Cathode Ray T______ experiment showed that by
deflecting a stream of particles with a magnet, atoms must contain
n_______ c______ p_______.
- This was significant because it showed that atoms were not
simply small indivisible “balls”, but rather had a s________.
- From the Cathode Ray Tube Experiment came the P____
P_____ model of the Atom.
(pg. # 1 continued…)
Evidence For the Positive Nucleus:
Rutherford’s G______ F_______ experiment:
Rutherford shot (+) particles at a sheet of gold foil.
Results: Most of the particles went ______ _______.
Some particles deflected s_______ b______
Analysis: 1.)This showed that most of the atom is in fact
e______ s_____
2.)Also, the positive charge is very c________ in a
small _________.
3.) This experiment disproved the _____ _____
______.
Chemistry Ch. 3 Notes (pg. # 2)
Question: What makes one element different from another?
Ex. Why is copper different than aluminum?
Hint: It probably has something to do with the ______.
Henry Moseley- English scientist who determined what made atoms of
the various elements unique from each other. He found that each
element has a unique p_______ c_______ in the nucleus, and thus a
certain n_______ of ________.
Atomic Number:
- Atomic Number- The number of p________ in the nucleus.
Elements are identified by their A_______ N_______.
Ex. Indicate which element has each of the following atomic
numbers:
a. 34 _________
b. 12 _________
c. 7 _________
d. 6 _________
Ions:
- A neutral atom has an e_______ number of protons
and e_______.
Ex. A neutral Li atom has ___protons and
____ electrons
- An _____ is an atom (or small molecule) that has
either _______ or_______ an electron or
electrons.
- Ions as a result have a net c________
Ex. Na (neutral) has ___ protons and ___ electrons
Na+ has ____ protons and ____ electrons
Ex. Determine how many protons and electrons each of the following
ions have.
Ca2+
Al3+
F-
N3-
Isotopes:
Isotope- Atoms of the s_______ element with a different number
of _________.
Ex.
Carbon-12 isotope:
____ protons, ____ neutrons
Carbon-14 isotope:
____ protons, ____ neutrons
Mass Number: The mass number of an isotope is the number of
________ plus the number of ________.
Ex.
Carbon-12
Ex. How many protons and neutrons does an Oxygen-15 atom have?
Protons = _______ Neutrons = ______
Notation of Isotopes:
Ex.
37
Cl
Ex. How many protons and neutrons do the following isotopes of
carbon have?
12
13
14
C
C
C
Chemistry Ch. 3 Notes (pg. # 3)
The Atomic Mass Unit:
1 a.m.u. is defined to be _____ the mass of a ________ isotope.
- In other words, a ________ isotope has a mass of exactly
______ a.m.u.
Average Atomic Mass and Relative Abundances of Isotopes:
- All isotopes of an element do not have the same _______.
- The Average Atomic Mass is a w_________ average of all
the isotopes of an element
-The average atomic mass appears on the _________
__________ of the ________.
6
C
12.011
- Certain Isotopes of an element are more s_______ than others. As
a result, there is a Relative Abundance of each isotope.
Relative Abundance- The percentage of an element that is composed of
a certain isotope.
ex. The relative abundance of 12C in carbon is 98.89%.
- So, in any sample of carbon, 98.89% of the
sample will be the carbon-12 isotope.
(note: Notice how the average atomic mass of
carbon is very close to 12 amu)
Calculating Average Atomic Mass:
Avg. Atomic Mass = (Mass of Isotope 1)(% abundance/100) +
(Mass of Isotope 2)(% abundance/100) +…
Ex. Strontium has four isotopes with the following masses:
83.913 amu (0.56%)
85.909 amu (9.86%)
86.909 amu (7.00%)
87.906 amu (82.58%)
Calculate the average atomic mass of strontium.