Transcript File

EOCT ReviewPhysical Science
The Structure of the Atom
The Structure of the Atom
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The NUCLEUS contains:
Protons-positively charged, mass of 1amu
 Neutrons-no charge, mass of 1amu
 All of the mass of an atom can be said to come from
the nucleus
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How do we know the number of protons?
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It is equal to the atomic number
How do we know the atomic number?
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We look on the periodic table!
The Structure of the Atom
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The number you see at the top of
each square on your table is the
ATOMIC NUMBER, or the
number of PROTONS.
It will always be a whole number.
Notice that as you go across the
table, the atomic numbers go up
by one each time you go over one
element.
No two elements have the same
atomic number or the same
number of protons.
The atomic number gives the
identity of the element.
The Structure of the Atom
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The number you see near the middle of
each square on your table is the
ATOMIC MASS, weighted average of
the isotopes of an element.
ISOTOPES are two atoms of the same
element with different numbers of
neutrons.
Some Boron atoms have 5 protons and
5 neutrons (MASS NUMBER=10).
Other Boron atoms have 5 protons and
6 neutrons (MASS NUMBER=11).
The ATOMIC MASS is the average of
all of the elements different MASS
NUMBERS.
Some questions might ask you to
calculate neutrons based on the atomic
mass. In this case your answer would be
10.811 - 5 = 5.811, or A.M. – P = N
The Structure of the Atom
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Isotopes have a certain notation
Name Notation: The name of the element followed by
the mass number
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Ex: Carbon-12 (N=6), Carbon-13 (N=7), and Carbon-14
(N=8)
Symbolic Notation
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12
6
C
13
6
C
14
6
C
In the symbolic notation, the mass number is always on top,
and the atomic number is always on the bottom
The Structure of the Atom
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The Electrons are NOT found in the nucleus
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Electrons are negatively charged
The mass of an electron is so much smaller than that of
protons and neutrons that they are insignificant to the mass
of the atom
They are found surrounding the nucleus in an Electron
Cloud
The electron cloud has different energy levels; as you
go farther away from the nucleus, the energy level has a
higher number
Electrons fill the energy levels according to the pattern:
2, 8, 8, 18, 18, 32, 32
The Structure of the Atom
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In an electrically neutral atom,
the electrons will be equal to the
number of protons.
You can find electrons by
looking at the periodic table and
the atomic number.
You can use the periodic table
to determine how the electrons
will fill the energy levels.
The series of numbers at the
very bottom tell you how many
electrons will fill into each level
as you go out.
Valence electrons are the
electrons in the outermost level:
Boron has 3 valence electrons.
The Structure of the Atom
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You always start filling in
electrons in the lowest,
innermost level first
You fill according to the
pattern: 2, 8, 8, 18, 18, 32,
32.
Boron has five electrons, 2
in the innermost level, then
three in the next.
The Structure of the Atom
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Valence electrons are the
outermost electrons
Look on your periodic table and
find the number of outermost
electrons for oxygen
You should find there are six
A Lewis Dot Diagram shows only
the valence electrons, in a box
type format
You put one on each of the sides;
once you cover four sides you
start pairing them.
The Structure of the Atom
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Remember, ISOTOPES are atoms with the same
number of protons and different number of neutrons
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Mass # – Atomic # (# of Protons) = # of Neutrons
Atomic Mass – Atomic # (# of Protons) = # of Neutrons
When two atoms have the same number of protons,
but a different number of electrons, they are called
IONS
Ions are either positively or negatively charged,
depending on whether you’ve lost or gained electrons
The Structure of the Atom
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Taking away electrons:
Boron is most likely to
lose 3 electrons
The negative electrons
and positive protons will
no longer be balanced
Do you think it will be a
positive ion, or negative?
Positive: B+3
Boron Atom and Ion
6
5
## of
of Subatomic
Subatomic Particles
Particles
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4
Protons
Electrons
3
2
1
00
Boron
Boron
Boron
Ion
Boron+3
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Adding electrons:
Fluorine is most likely to
gain 1 electron
The negative electrons
and positive protons will
no longer be balanced
Do you think it will be a
positive ion, or negative?
Negative: F-1
Fluorine Atom and Ion
10
9
8
# of Subatomic Particles
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7
6
Protons
5
Electrons
4
3
2
1
0
Fluorine
Fluorine Ion
The Structure of the Atom
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The OCTET Rule
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Atoms will gain or lose electrons in order to have a full outer
shell of electrons
This means 8 electrons, or an octet (noble gases)
You have to look at the element to see whether it is more
likely to gain electrons to have eight, or to lose electrons and
have the eight from the level below
Ex: Mg has 12 electrons, is it closer to the noble gas Ne
which has 10 electrons, or the noble gas Ar which has 18?
Neon, so magnesium is going to lose 2 electrons to be like
Ne. Will this be a positive ion or a negative ion?
Positive! It will be Mg+2
The Structure of the Atom
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MEMORIZE these groups
Group 1: H-Fr will be +1
 Group 2: Be-Ra will be +2
 Group 15: N-Bi will be -3
 Group 16: O-Po will be -2
 Group 17: F-At will be -1
 Notice that those to the left are likely to be positive
(lose electrons), those on the far right are likely to be
negative (gain electrons)
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The Periodic Table
The Periodic Table
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The Periodic Table is an orderly arrangement of all of
the discovered elements, as well as some predicted
elements
The first periodic table was arranged according to
atomic mass by Dmitri Mendeleev; he used index cards
to teach his students the elements
The modern periodic table was arranged by Henry
Mosely, in order of increasing atomic number
The table has 18 groups, or columns, also called
families
It has 7 rows, or periods
Periodicity is the term that means when the elements
are placed in order, you see periodic, or repeating,
trends in their properties
Alkaline Earth Metals
Noble Gases
The Periodic Table
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Group 1-Alkali metals
The most reactive metals on the table, react readily
with water
 Charge of +1
 Metals conduct electricity and have luster
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Group 2-Alkaline Earth Metals
Reactive, but less than alkali metals
 Charge of +2
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The Periodic Table
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Groups 3-12-Transition metals
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These metals have different charges, some metals
even having two possible charges
Group 17-Halogens
The most reactive non-metals
 Charge of -1
 Are found as diatomic molecules F2, Cl2, if not in a
salt with a metal, NaCl, KF
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Group 18-Noble Gases
Filled valence shell
 Also called inert gases, because they are so stable
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The Periodic Table
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Atomic Radius: the size of an atom
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As you go across the table in one period, the radius gets
smaller, because the increasing number of protons pulls the
electrons in tighter
As you go down a group the radius gets bigger because the
electrons start filling energy levels that are farther and farther
out
Electronegativity: the likelihood an element will gain an
electron
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Goes up as you go across, because the elements get closer to
having a full octet
Goes down as you go down a group, because the electrons
are farther from the nucleus
Matter and its Properties
Matter and its Properties
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Matter is anything that has mass and takes up space (volume)
The relationship between mass and volume is called density
Density=mass/volume,
or mass divided by volume
Matter and its Properties
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Mass is found by using a balance
Volume can be found either by using the formula
l x w x h for a cubic rectangle, or by using a graduated
cylinder for liquids
The volume of an irregularly shaped solid can be found
by using the water displacement method
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First you measure the volume of an amount of water
Second, you drop in the solid you need to know the volume
of
Last, you subtract the original volume and the volume from
the volume of the water plus the solid, the difference is the
volume of the solid
Matter and its Properties
Matter and its Properties
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Homogeneous mixtures are also called solutions
Solutions are when one thing is dissolved in something
else
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The substance that is dissolved is called the solute
The substance the solute is dissolved in is called the solvent
Example: Sugar in coffee
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Solute: sugar
Solvent: coffee
Example: Air
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Solutes: oxygen, argon, carbon dioxide
Solvent: nitrogen
Matter and its Properties
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Solutions have a measure called concentration
Concentration means how much solute is dissolved in
the solvent
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Saturated means that the solution can not hold any more
solute, any extra would sink to the bottom
Unsaturated means that you could dissolve more solute
without any sinking
Supersaturated means that the conditions are such that you
could actually dissolve more than what “should” go in
A different approach:
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Concentrated-a lot of solute in the solvent
Dilute-not much solute in the solvent
Electrolytes are solutions which conduct electricity;
these include salts, acids, and bases
Matter and its Properties
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Solubility Curves can
compare the solubility of
different salts at a range
of temperatures
Which salt has the
highest solubility at
10 degrees?
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KI
Which salt has the lowest
solubility at 40 degrees?
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Ce2(SO4)3
Matter and its Properties
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Acids and Bases
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Both are electrolytes, which means they conduct electricity
The pH scale is a range that tells you how strong an acid or base
is
pH less than seven are acids, with the strongest being close to
zero
pH higher than seven are bases, with the strongest being close to
fourteen
Matter and its Properties
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Acids
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Contain an H+ ion
Taste sour
Turn litmus red
pH less than 7
Start with H: HCl, HNO3, H2SO4
Bases
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Contain OH- ion
Taste bitter
Turn litmus paper blue
pH greater than 7
Turns phenolphthalein fuschia
End with OH: NaOH, KOH, Mg(OH)2
Matter and its Properties
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Neutralization
An acid plus a base will give you a neutral salt in
water
 Example:
HCl + NaOH = NaCl + HOH
(H2O)
 This is called a neutralization reaction; the positive
ion from the base combines with the negative ion
from the acid to form the salt
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Bonding
Bonding
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There are two main types of compounds
Ionic
a metal and a non-metal
 electrons are gained and lost
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Covalent
between two or more non-metals
 electrons are shared
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Another type of bond is metallic, where
electrons are pooled
Bonding
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Ionic Bonds
a metal from the left side of the table, joins with a
non-metal from the right side
 they can be shown using Lewis dot diagrams
 the metals lose electrons to form an octet
 non-metals gain the electrons
 sometimes you might have to use more than one of
either the metal or the non-metal to get the dots to
cancel out
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Bonding
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NaCl
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MgO
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Since they both
have two, you
reduce the
formula to one
each
CaCl2
Bonding
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Ionic formulas can be found by using the crossover
method
Bonding
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Naming Ionic Compounds:
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For Binary Compounds (two elements):
First, write the name of the metal
 Then, write the negative ion with the ending changed to –
ide
 Example: Na+1 and Cl- becomes sodium chloride
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For Tertiary Compounds (two or more elements):
First, write the name of the positive ion
 Then, write the name of the polyatomic ion, or if the
negative ion is a single element, change the ending to –ide
 Examples: Mg+2 and NO2- become magnesium nitrite
NH4+ and Cl- become ammonium chloride
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Bonding
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Some metals have more than one charge
Their formula and name will depend on the
charge
Ex: Copper can either be +1 or +2
Cu+1 would be CuCl, or Copper (I) chloride
 Cu+2 would be CuCl2, or Copper (II) chloride
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If you have the formula and not the name, you
must use the reverse crossover to find which
charge is correct
Bonding
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Covalent Compounds come from sharing electrons
Bonding
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Covalent compounds-you know a compound is
covalent if the first element is a non-metal
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Ex: CCl4
Covalent compounds use prefixes in their names
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1
2
3
4
5
6
7
8
9
10
mono
di
tri
tetra
penta
hexa
hepta
octa
nona
deka
Bonding
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The prefixes can be used either to find the name
from a formula, or the formula from a name
You don’t use mono on the first element
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Example: NO2
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Nitrogen dioxide
Example: diphosphorus trisulfide
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P2S3
Reactions
Reactions
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The left side of a reaction is called the reactants
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On the right side of the arrow, you find the
products
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These are what you start with
These are what you finish with
The Law of Conservation of Matter states that
all atoms on the right must be balanced with the
atoms on the left
Reactions
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There are five main types of reactions that
involve electrons
Reactions involving electrons are called chemical
reactions
Synthesis-when two or more small things make one
larger compound
A + B → AB
2H2 + O2 → 2H2O
 Analysis/Decomposition-when one larger thing
breaks down into smaller parts
AB → A + B
2NaCl → 2Na + Cl2
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Reactions
Single Replacement-when an individual element
reacts with a compound and two ions switch places
A + BC → AC + B
Zn + 2HCl → ZnCl2 + H2
 Double Replacement-when two compounds react
together and two ions switch places
AB + CD → AD + CB
KOH + NaCl → KCl + NaOH
 Combustion-this is a specific type of synthesis
reaction in which one reactant is always oxygen
A + O → AO
2Mg + O2 → 2MgO
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Reactions
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Balancing Chemical Reactions
The main function is multiplying
 Ex: Fe + S → Fe2S3
1
1
2 3
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2Fe + S → Fe2S3
2
1
2 3
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2Fe + 3S → Fe2S3
2
3
2 3
Reactions
Sometimes you have to add if an element is in more
than one place on the same side of the arrow
 Ex: NO + O2 → NO2
Total O 3
2
Total N 1
1
 Try to even up any odd numbers by multiplying by 2,
then balance
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2NO + O2 → 2NO2
Total O 4
4
Total N 2
2
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Radioactivity
Radioactivity
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Nuclear radioactivity comes from nuclear
reactions
Nuclear reactions are those that involve the
protons and neutrons in radioactive isotopes
Isotopes with equal protons and neutrons are
the most stable
Nuclear radiation gives off very high energy
compared to chemical (electron) reactions
This radiation can be harmful if you aren’t
careful, but it can also be very useful!
Radioactivity
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There are three main types of nuclear radiation
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Alpha radiation-lowest in energy, can be stopped by
paper or a few cm of air
238
92U
4
→ 2He
234
+ 90Th
Beta radiation-higher in energy, can be stopped by
metal or thick clothes
14
6C
0
-1e
14
+ 7N
238
92U
4
→ 2He
→
 Gamma radiation-accompanies either alpha or beta,
highest in energy, can be stopped by thick steel or
concrete
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234
+ 90Th
0
+ 0
Radioactivity
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Nuclear fusion is when two or more nuclei join
together to make one larger nucleus
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high temperature is required, this is where we get
energy from the sun
Nuclear fission is when nuclei split apart
occurs with elements with atomic number higher
than 90
 causes a nuclear chain reaction and gives off high
energy
 This is what happens in nuclear power plants
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Radioactivity
Half-Life
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A half-life is the amount
of time that it takes a
radioactive substance to
lose half of its mass due
to decay
Ex: a 10g sample of a
radioactive substance with
a half-life of 5 days
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In 5 days you have 5g
In 10 days you have 2.5g
In 15 days you have 1.25g
And so on and so on
Mass vs. Time
12
10
8
Mass (g)
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6
4
2
0
0
5
10
15
Time (days)
20
25
Radioactivity
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Radiation Exposure
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Benefits of radiation
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We are exposed to radiation everyday; from the sun, from natural
radioactive isotopes, and others
This kind is called background radiation
Tracers and therapy in medicine
Irradiation of food to make it last longer
In smoke detectors
Carbon-14 dating of fossils
Clean power source
Dangers
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Radiation can be dangerous if you are exposed to very high levels
Radiation sickness can vary depending on the time, amount, and type
of radiation
There will be a warning sign on any high radiation area
Energy Transformations
Energy Transformations
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Energy is the capacity to do work
Energy can be transferred but is not lost; this is the Law
of Conservation of Energy
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The form may change, but is not created or destroyed
There are many different types of energy
Kinetic-energy of motion
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Mechanical-energy due to matter in motion
Electromagnetic-energy due to moving electrons
Thermal (heat) energy-energy due to the internal motion of
atoms
Sound energy-energy due to matter vibrating and traveling in a
wave
Light energy-energy of certain wavelengths of the
electromagnetic spectrum
Energy Transformations
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Potential Energy-stored energy
Chemical energy-the energy stored in chemical
bonds, is released when bonds are formed or broken
 Gravitational energy-energy due to having the ability
to fall, once the object falls it will have kinetic energy
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At the top of a roller coaster you have potential energy, as
you come down the hills, you have kinetic energy
Energy can be changed
Turbines turns heat energy from burning fuel into
mechanical energy
 Generators turn mechanical energy into electricity
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Energy Transformations
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Heat is a measure of the energy of particles (or
the movement of particles)
Temperature is a measure of the average kinetic
energy
They are not exactly the same thing
Energy transfer, or heat flow, goes from higher
energy to lower, or hotter to colder
What you are studying is called the system,
everything around it is called the surroundings
Energy Transformations
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Conduction-when heat is transferred by contact and the
collision of particles
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Convection-when heat is spread out by differences in
density and currents
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warm air mixing in the environment due to currents
Radiation-when heat is transferred through empty space
by means of electromagnetic waves
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a pot on a stove
a heating pad
The sun warming up the surface of the earth
The microwave cooking your lunch
Insulators like styrofoam and ceramic prevent the flow
of heat
Energy Transformations
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A heating curve shows the
change in temperature vs
time as heat is added
As you go across the x-axis,
heat is added
Heat can be calculated using
the change in temperature,
the mass, and the specific
heat
Specific heat is the amount of
heat energy needed to raise
1g of a substance by 1 degree
Celcius or Kelvin
A calorimeter is a devise used
to measure heat
Energy Transformations
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Phase diagrams show how a
substance can change from
solid, liquid, or gas due to
pressure or temperature
The triple point is the
specific T and P where all
three phases exist
simultaneously
The critical point is the point
where a substance can no
longer exist as a liquid
Waves
Waves
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Waves provide a means of transferring energy from one
place to another without transferring matter
The wave moves through a medium
Longitudinal waves have matter which vibrate in the
same direction as the disturbance-think of a slinky
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Rarefaction-parts where the coils are spread out
Compression-parts where the coils are close together
Wavelength-distance between one compression to the next
Amplitude-half the distance between two compressions
Frequency-the number of waves per second, the unit is Hz
Waves
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Transverse Waves-matter moves perpendicularly to the direction
of the disturbance
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Crest-the highest point of the wave
Trough-the lowest point of the wave
Wavelength-the distance from one point on a wave, to the same point on
the next wave
Amplitude-the height of the wave from the midpoint to the crest
Frequency-the number of waves per second
Waves
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The speed of a wave is the wavelength times the
frequency
The speed of ALL light waves is the same,
the speed of light=3x108m/s
Waves
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Light waves are special in that they do not need
a medium to travel through; they can move
through empty space
They are called electromagnetic waves because
they have alternating electric and magnetic fields
Light behaves like waves and particles; the
particle is called a photon
the photon is a bundle of light energy; it has
wavelike behavior
Waves
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Light waves are special in that they do not need a medium to
travel through; they can move through empty space
Reflection-the bouncing back of a wave from a surface such as a
mirror
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Refraction-the bending of light when it hits a new medium
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
The angle that it bounces back will be equal to the angle that it hit the
surface
Such as light bending when it goes from air to water
Diffraction-the scattering of light as it hits the edges of a
boundary or tiny opening
Interference is when two or more waves are moving through a
medium at the same time
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They can amplify each other (constructive interference)
They can distort or muffle each other (destructive interference)
Waves
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Objects that emit their own light are luminous
Objects that only reflect light are illuminated
Lenses bend light:
Convex lenses bend light to make the light rays
converge to a single point
 Concave lenses bend light to make the rays diverge
and go in opposite directions

Waves
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Sound waves are longitudinal, or compressional, waves
Matter is necessary for sound waves to carry
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They can’t travel in the vacuum of space
Amplitude gives the sound its intensity, or loudness
measured in decibels (dB)
Frequency gives it its pitch, or highness or lowness,
measured in hertz (Hz)
Sound that is irregular or unpleasant is called noise
Sound that has a pleasing quality with regular patterns is
called music
Force, Mass, and Motion
Force, Mass, and Motion
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
Speed-also called velocity=distance/time
Velocity describes speed and direction

Ex: if you are driving to California at 50mi/h, then the
velocity is 50mi/h west
Force, Mass, and Motion

Acceleration is the change in velocity over time


Ex: if you are at a red light, your velocity is 0mph; the acceleration has to
do with changing your velocity and the amount of time it takes to change
it
Acceleration can be negative if you slow down, or drive in the
opposite direction
Force, Mass, and Motion
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An object has mass, but weight is a measure of the
gravitational force on the object
Free fall is what happens when something is under the
influence of gravity
Gravity has an acceleration of 9.8m/s2
Everything falls at the same rate, unless there is
something that causes air resistance such as a parachute
Other things may affect velocity, such as friction when
moving something across carpet, or wind acting with or
against an airplane
Force, Mass, and Motion

Newton’s First Law

Law of Inertia-an object at rest will remain at rest
and an object in motion will remain in motion,
unless acted upon by an outside force
Inertia is an object’s resistance to move
 When you slam on the brakes, your body keeps moving;
until the seatbelt stops you

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Newton’s Second Law

Law of Acceleration-when an unbalanced force
causes an object to accelerate, the acceleration is
directly proportional to the force and inversely
proportional to the mass

F=m*a
Force, Mass, and Motion

Newton’s Third Law

Law of Conservation of Momentum-For every
action (force), there is an equal and opposite reaction
Momentum (P) is mass times velocity
 P=m*v
 Ex: if a 20kg cart travels at 5m/s and runs into a 10kg cart
going in the opposite direction at 10m/s what will happen
 They will stop where they meet, the momentum of each
will cancel the other out

Force, Mass, and Motion

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Work-when a net force causes an object to change its
state of motion or rest, causing it to speed up, slow
down, or change direction
Work = force times distance
The unit is Joules (J) 1J = 1N*m
Holding a 100lb box is not work, but moving it is
A machine makes work easier by



Decreasing the required input force
Increasing the distance the resistance force moves
Changing the direction of the input force
Force, Mass, and Motion


The advantage of using a machine is called mechanical
advantage; when MA is large, less effort is needed
You need to know the resistance force and the effort
force

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Actual mechanical advantage = resistance force/effort
force


Effort force is the force you put in
The resistance force is what you’re working against
(sometimes the weight of the object you’re moving)
AMA = Fr/Fe
Ideal mechanical advantage=effort length/resistance
length

IMA = effort length/resistance length
Force, Mass, and Motion

If you work against friction your work input
includes friction
work input = work output + work against friction
 Efficiency = (work output/work input) *100%


There are six types of simple machines

Inclined plane-ramp
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The length of the ramp is the effort length, the height is
the resistance length
Wedge-ax, nail, chisel

The longer and thinner, the better the MA
Force, Mass, and Motion

Screw-inclined plane wrapped around a cylinder


Lever-bar that pivots around a fulcrum


The effort length and resistance length are always
measured from the fulcrum
Wheel and axle-larger circle is the wheel, smaller
circle is the axle


The closer the threads are together, the higher the MA
IMA = radius of wheel/radius of axle
Pulley-a rope or chain moves the wheel

The more ropes supporting the resistance, the greater the
MA
Electricity and Magnetism
Electricity and Magnetism


Electricity is caused by action of charged
particles
Static electricity comes from the buildup of
electric charges on the surface of objects
Static means not moving, so this is electricity that
does not flow
 Can come from friction, conduction, or induction
 When the static charge is suddenly lost, it is called
discharge; lightning is an example
 Grounding protects you from being electrocuted by
sending stray charges to the earth or ground

Electricity and Magnetism

Current electricity is electricity that flows
It flows through a circuit, or closed pathway
 Electromagnetic generators produce current as a coil
of wire moves through a magnetic field, this is called
alternating current (AC)
 Electrochemical cells, or batteries, produce current
from chemical reactions called direct current (DC)
 Thermocouples produce current from heat energy
 Photocells or solar cells produce electricity when
light hits photosensitive materials where electrons
can be given off
 Piezoelectric currents are produced due to pressure

Electricity and Magnetism







Conductors conduct electricity-they have space in the
valence shells for electrons to flow freely
Insulators do not conduct-their valence shells are too
full
A fuse is a piece of metal that will melt if the flow of
electricity gets too hot, once the fuse melts, the circuit
is open and electricity will not flow
Circuit breakers work the same way if the electricity
exceeds safe levels
Circuits can either be in series (one after the other) or
parallel (alternate branches)
If a series circuit gets interrupted, the flow will stop
If a parallel circuit gets interrupted, the flow will follow
one of the other paths
Electricity and Magnetism

Series Circuits-One path: if one bulb goes out, all
others will also
Electricity and Magnetism

Parallel Circuits-More than one path: if one bulb goes
out, all others can stay on
Electricity and Magnetism




Coulomb-unit of charge
Ampere-unit of current, coulombs/second, C/s
Voltage is the energy V=J/C
Resistance is measured in Ohms


Watts measure electrical power


Ohm’s Law: resistance = voltage/current R=V/I
P = voltage * current = VI unit is watts
Energy is the kilowatt-hour

Energy = power * time = Pt
Electricity and Magnetism


Magnetism is a force produced by the motion of
charged particles
The flow of electrons can form an electromagnet
If you wrap a copper wire into coils, then as electricity
flows from each end, the wire will become a magnet
 The more coils you have, the stronger the magnetic


A magnetic field can produce an electric current
An electric motor has a rotating electromagnet that
creates electricity
 This is called electromagnetic induction
