MATTER
I. What is matter:
STATES OF MATTER ARE: __________,______________,____________,____________
Describe each state of matter with respect to: Particle Distance and Compressibility
SOLID
LIQUID
GAS
______________
________________
___________________
______________
________________
___________________
The following table summarizes properties of gases, liquids, and solids and identifies the microscopic behavior
responsible for each property.
Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the
Behavior
gas
liquid
solid
assumes the shape and volume
of its container
particles can move past one
another
assumes the shape of the part
of the container which it
occupies
particles can move/slide past
one another
retains a fixed volume and
shape
rigid - particles locked into
place
compressible
lots of free space between
particles
not easily compressible
little free space between
particles
not easily compressible
little free space between
particles
flows easily
particles can move past one
another
flows easily
particles can move/slide past
one another
does not flow easily
rigid - particles cannot
move/slide past one another
II. Physical vs. Chemical Properties
A. PHYSICAL PROPERTIES:
Physical properties of matter are categorized as either Intensive or Extensive:
o
Intensive - Properties that do not depend on the amount of the matter present.
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o
Color
Odor
Luster - How shiny a substance is.
Malleability - The ability of a substance to be beaten into thin sheets.
Ductility - The ability of a substance to be drawn into thin wires.
Conductivity - The ability of a substance to allow the flow of energy or electricity.
Hardness - How easily a substance can be scratched.
Melting/Freezing Point - The temperature at which the solid and liquid phases of a
substance are in equilibrium at atmospheric pressure.
Boiling Point - The temperature at which the vapor pressure of a liquid is equal to the
pressure on the liquid (generally atmospheric pressure).
Density - The mass of a substance divided by its volume
Extensive - Properties that do depend on the amount of matter present.
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Mass - A measurement of the amount of matter in a object (grams).
Weight - A measurement of the gravitational force of attraction of the earth acting on an
object.
Volume - A measurement of the amount of space a substance occupies.
Length
B. CHEMICAL PROPERTIES:
Chemical properties of matter describes its "potential" to undergo some chemical change
or reaction by virtue of its composition.
It is quite difficult to define a chemical property without using the word "change".
Eventually you should be able to look at the formula of a compound and state some
chemical property. At this time this is very difficult to do and you are not expected to be
able to do it.
For example hydrogen has the potential to ignite and explode given the right conditions.
This is a chemical property.
Metals in general have they chemical property of reacting with an acid. Zinc reacts with
hydrochloric acid to produce hydrogen gas. This is a chemical property.
IN GENERAL
Physical properties:
Chemical
properties:
Properties that do not change the chemical
nature of matter
Properties that do change the chemical
nature of matter
III. AN ORGANIZATIONAL CHART TO HELP UNDERSTAND THE CLASSIFICATION, STRUCTURE,
AND RELATIONSHIPS THAT EXIST IN “MATTER”
IV. HISTORY OF ATOMIC THEORY (MAIN PLAYERS AND CONTRIBUTIONS)
V. SUBATOMIC PARTICLES AND SYMBOL NOTATION
Name
protons
Symbol
p
Mass
1u
Charge
1+
Location
part of the nucleus
n1
1u
0
part of the nucleus
1/1837 u
1–
normally at large distances from the nucleus
1
1
1
neutron
0
electron
-1e
0
Atomic Number (Z)
The atomic number is the number of protons in the nucleus of an atom. It is listed on the periodic
table for each element. No two elements have the same atomic number (or the same number of protons),
so the atomic number identifies the element.
Mass Number (A)
Mass number: (symbol: A) total number of protons and neutrons in the nucleus (not listed on the
periodic table, since it varies). NOTE this number is a whole number. Atomic Mass is different.
Atoms of the same element have the same atomic number, but may have different mass numbers.
Isotopic notation for a particular atom (also called nuclide symbol notation):
A
E
Z
(E = element's symbol; A = mass number; Z = atomic number)
For example:
23
Na
11
Represents a sodium atom which always has 11 protons and in this case has a mass number of 23.
(Note: This means that there are 12 neutrons. 23 - 11 = 12)
Mass number - atomic number = # neutrons
Determining the number of electrons- [*THE NUMBER OF ELECTRONS CAN CHANGE]
The number of electrons in an element can change.
NEUTRAL ATOMS: the number of protons is exactly equal to the number of electrons
IONS: charge on the ion tells you the number of electrons.
POSITIVE IONS: LOST THE NUMBER OF ELECTRONS EQUAL TO THE CHARGE
NEGATIVE IONS: GAINED THE NUMBER OF ELECTRONS EQUAL TO THE CHARGE
Complete the next page on counting the number of particles in an atom or ion:
VI. ISOTOPES AND AVERAGE ATOMIC MASS
Example #1: Carbon
mass number exact weight percent abundance
12
12.000000
98.90
13
13.003355
1.10
This is the solution for carbon:
(12.000000) (0.9890) + (13.003355) (0.0110) = 12.011
Example #2: Nitrogen
mass number exact weight percent abundance
14
14.003074
99.63
15
15.000108
0.37
This is the solution for nitrogen:
(14.003074) (0.9963) + (15.000108) (0.0037) = 14.007
Calculate the average atomic weight for:
1) magnesium
mass number exact weight percent abundance
24
23.985042
78.99
25
24.985837
10.00
26
25.982593
11.01
2) molybdenum
mass number exact weight percent abundance
92
91.906808
14.84
94
93.905085
9.25
95
94.905840
15.92
96
95.904678
16.68
97
96.906020
9.55
98
97.905406
24.13
100
99.907477
9.63
VII. NUCLEAR CHANGES (UNSTABLE ISOTOPES AND RADIOACTIVE DECAY)
A. RADIATIONS:
Alpha Decay
The reason alpha decay occurs is because the nucleus has too many protons which
cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is
emitted. The way it works is that the Helium nuclei are in constant collision with the
walls of the nucleus and because of its energy and mass, there exists a nonzero
probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out
of the nucleus. Here is an example of alpha emission with americium-241:
Alpha Decay of Americium-241 to Neptunium-237. Adapted from Alpha Decay.
Beta Decay
Beta decay occurs when the neutron to proton ratio is too great in the nucleus and
causes instability. In basic beta decay, a neutron is turned into a proton and an
electron. The electron is then emitted. Here's a diagram of beta decay with hydrogen3:
Alpha Decay of Hydrogen-3 to Helium-3. Adapted from Stability of Nuclei.
There is also positron emission when the neutron to proton ratio is too small. A
proton turns into a neutron and a positron and the postiron is emitted. A positron is
basically a positively charged electron. Here's a diagram of positron emission with
carbon-11:
Positron Decay of Carbon-11 to Boron-11. Adapted from Types of Radioactivity.
The final type of beta decay is known as electron capture and also occurs when the
neutron to proton ratio in the nucleus is too small. The nucleus captures an electron
which basically turns a proton into a neutron. Here's a diagram of electron capture
with beryllium-7:
Electron Capture of Beryllium-7. It decays to Lithium-7. Adapted from Electron
Capture.
Gamma Decay
Gamma decay occurs because the nucleus is at too high an energy. The nucleus falls
down to a lower energy state and, in the process, emits a high energy photon known as
a gamma particle. Here's a diagram of gamma decay with helium-3:
B. TRANSMUTATION REACTIONS:
When a nucleus is unstable it either splits apart spontaneously into fragments or else ejects small
particles. The end result of this "decay" is either a more stable nucleus or a completely stable (nonradioactive) nucleus.
The emission of the small particles and any energy that accompanies them is called radioactivity.
The phenomenon was first described by the French scientist Henri Becquerel and the general
characteristics of the small particles given off during decay were determined through experiment by
Rutherford.
The common pathways for nuclear decay include the following:
type of decay
alpha beta positron electron capture gamma
particle involved
none
symbol
C. HALF-LIFE PROBLEMS: (RADIOACTIVE DECAY)
Half-life: time is takes for ½ of a radioactive sample to decay.
Fill in the data table for the quantity at time= t [q(t]] for a radioactive isotope with a
Half life of 10.0 days and create a decay graph:
Time (t)
days
0
Quantity (q(t))
grams
100
q(t) = q(t=0)/2( # ½ lives)
where the: # 1/2 lives = time/ ½ life
Sample Problems: (1st 3 are simple diagram problem)
1. The half life of a certain radioactive substance is 12.5 hours. How much of a 40.00 g sample will
remain after 50.0 hours:
2. If 100.00 grams of a radioactive substance decays to a mass of 6.250 grams in 1.5 x 10 4 years, what is its
Half life?
3. If 54.000 grams of a radioactive substance remains after 180 days, how much was in the original sample
If its half life is 30.0 days.
4. How much time would be required for the substance in problem #1 to decay to a mass of 20.00 g.
5. What is the half life of a radioactive substance if a mass f 23.625 g decays to a mass of 18.595 g
In 2.456 hours.