midterm review sheet

Define Chemistry
Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes.
If you were studying properties of diamonds (diamonds are made of carbon), you would be studying ______ chemistry.
organic
If you were studying how the intake of potassium affects the production of ATP, you would be studying ______ chemistry.
biochemistry
If you were studying the energy given off by a combustion reaction, you would be studying _____ chemistry.
physical
If you were studying how oxygen binds to hemoglobin (contains iron), you would be studying __________ chemistry.
inorganic
If you were studying the composition of wool to determine how to make clothes softer, you would be studying _______ chemistry.
analytical
If you used computers to put together a model that showed the destruction of the ozone layer, you would be studying _________ chemistry.
theoretical
Use the definitions of basic research and applied research to distinguish the two terms.
Basic research is carried out for the sake of increasing knowledge, such as how or why a specific reaction occurs and what the properties of a substance are. On the other hand, applied research is generally carried out to solve a problem.
What is the benefit of technological development? Name one example of technological development in our society.
The benefit is that it improves the quality of our lives. EX: biodegradable materials, computers, air conditioning
Define matter. Define mass.
Matter- anything that has mass and takes up space.
Mass- a measure of the amount of matter.
What are the four basic building blocks of matter?
atom, element, compound, molecule
Define element.
element- a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom.
Define atom
the smallest unit of an element that maintains the chemical properties of that element.
What are extensive properties? Give one example
Extensive properties depend on the amount of matter present.
EX: volume, mass, amount of energy in a substance
What are intensive properties? Give an example.
Intensive properties do not depend on the amount of matter present.
EX: melting point, boiling point, density, color, texture, hardness
Four physical properties of a classroom desk.
1) three feet off the ground
2) tan colored
3) solid
4) flat surface
What are three physical changes involved in cooking?
1) cutting
2) melting
3) boiling
List two changes of state. Are changes of state classified as physical or chemical changes?
1) melting
2) boiling
Changes of state are classified as physical changes.
Solids have a _________ volume and __________ shape.
Solids have a definite volume and a definite shape.
Liquids have a ______ volume and _________ shape.
Liquids have a definite volume and an indefinite shape.
Gases have a ______ volume and _______ shape.
Gasses have an indefinite volume and an indefinite shape.
What is the main difference between a physical property and a chemical property?
A physical property is a characteristic that can be observed or measured without changing the identity of the substance, whereas a chemical property relates to a substances ability to undergo changes that transform it into different substances. Physical properties can be observed without changing the identity of the substance, chemical properties can not.
List three chemical changes involved in cooking
baking chicken, grilling hamburgers, frying shrimp
Chemical changes involve reactants and products. What is the difference between these two terms.
Chemical changes begin with reactants which turn into products
The law of conservation of mass states that the mass of the _______ must equal the mass of the _______.
The law of conservation of mass states that the mass of the reactants must equal the mass of the products.
Matter can be divided into two categories. What are they?
1) pure substances
2) mixtures
What is the difference between a homogeneous mixture and a heterogeneous mixture? Give an example of each.
homogeneous is consistent throughout (sweet tea)
heterogeneous is not consistent throughout (salsa)
An _________ like lithium or a ________ like salt can both be considered pure substances.
An element like lithium or a compound like salt can both be considered pure substances
A compound can be broken down into elements by what kind of change?
a chemical change
Horizontal rows on the periodic table are called _________.
periods
Vertical columns on the periodic table are called _________.
groups
What is the scientific method?
A logical approach to solving problems
List the four steps to the scientific method.
observe, hypothesize, experiment, conclude
There are two types of data. What are they? How can you tell the difference between the two?
1) qualitative – data that deals with descriptive information
2) quantitative- data that deals with numerical information
When testing a hypothesis the experimenter should use controls, why?
To have a way to compare the results of your experiment
Use the definition of dependent variable and independent variable to distinguish the two terms.
dependent variable- the variable that changes because of the independent variable
independent variable- the variable that is changed by the scientist
If you were to do an experiment to test to see which paper towel was the most absorbent, list three controls.
1) amount of paper towel used
2) amount of liquid used
3) type of liquid used
Based on the paper towel experiment, what would be the independent variable and the dependent variable?
independent variable- paper towel brand
dependent variable- how much liquid was absorbed
What is the next step if the hypothesis is not supported by the experiment?
Either revise or reject the hypothesis.
What is a theory? What is a hypothesis?
theory- a broad generalization that is supported by many experiments

hypothesis- a testable statement

What two things make up a measurement?
1) number
2) unit
The SI Units are used across the world for science. Why is it important that scientists all use the same units?
So that scientists across the world use the same units which allows results to be shared
List the seven SI base units.
meter, gram, second, kelvin, mole, ampere, candela
How are the base units manipulated to account for large and small measurements?
prefixes are added
How does mass differ from weight?
mass is not dependent on gravity, weight is
What does volume measure? List three units for volume.
Volume measures the amount of space an object takes up.
Units for volume:
1) cm cubed
2) mL
3) L
What is the formula for density? What is the unit for density?
D= m/v
density = mass divided by volume.
the unit for density is g/mL or g/cm^3
Can density be measured directly? How did we determine the density of a penny in the penny lab?
No. In the penny lab we used a scale to find the mass, then the water displacement method to find volume. We then calculated density with the formula.
Why does ice float in water?
Ice has a lower density than water.
Convert 435g to mg.
435,000 mg
convert 3.54 cm^3 to L.
3.54cm^3 = 3.54mL = 0.00354 L
What is the difference between accuracy and precision?
accuracy- the closeness of a measurement to the accepted value
precision- the closeness of a set of measurements to each other
Are the following test scores accurate, precise, neither or both? 74, 70, 76
They are precise but not accurate
What does the percent error tell you about your experiment? Is a high percentage or a low percentage a more accurate experiment?
How close your data is to the accepted data. A low % is a more accurate experiment
If the actual value for the density of copper is 7.34 g/mL and the value you recorded after your lab was 8.42 g/mL, what is the percent error of your experiment?
[(accepted-experimental)/accepted]*100
[(8.42-7.34)/7.34]*100=14.7%
How many significant figures in each of the following numbers?
a) 52.5200
b)3003
c)20300
d)3.500
e)0.00254
f)900
g)200500.0
h)8290
i)0.00520
a)5
b)4
c)3
d)4
e)3
f)1
g)7
h)3
i)3
Who was the first person to believe that matter was made up of smaller particles?
Democritus
Was Democratis supported? why or why not?
no, there was no proof for his ideas
Why did it take nearly 2,000 years before anyone developed these ideas of whether matter is made of smaller particles or not?
It was not until then that there was technology that allowed proof
State the laws of definite and multiple proportions; be able to identify both on the exam.
law of definite proportions- a compound contains the same elements in the same proportions by mass regardless of the size or source of the compound

law of multiple proportions- if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always in a ratio of small whole numbers

Who developed atomic theory?
Dalton
What is the first statement of the atomic theory?
all matter is composed of small particles called atoms
What are the two modifications that have been made to the atomic theory?
1) atoms are divisible
2) not all atoms of the same element are identical
Define atom
the smallest particle of an element that retains the chemical properties of that element
What are the three subatomic particles that make up the atom?
proton, neutron, and electron
Who discovered that subatomic particles existed by performing the cathode ray experiment?
Thomson
How did scientists determine that the cathode ray was composed of negatively charged particles?
When a negative plate was put up to the glass tube, the cathode ray inside bent away from the negative charge.
Describe the setup of Rutherford’s gold foil experiment.
Rutherford shot alpha particles at a sheet of gold foil, the experiment was surrounded by zinc sulfide which would flash if hit by the alpha particle.
What surprised scientists when observing the gold foil experiment?
That some of the alpha particles hit the gold foil and bounced back
What result of the gold foil experiment proved that the atom was made mostly of empty space?
Most of the alpha particles went straight through undisturbed.
What result of the gold foil experiment proved that the nucleus was dense?
Whatever caused the large alpha particle to stop and change direction must be massive, a large mass and a small volume means that the particle is dense
What result of the gold foil experiment proved that the nucleus was positively charged?
The positive charged alpha particles were deflected. Like charges repel one another
What do nuclear forces do?
They hold the nucleus together
What two particles are located inside the nucleus?
proton and neutron
The number of protons in an atom can also be called the ________.
atomic number
Isotopes differ in two ways. What are the two ways?
1) number of neutrons
2) mass
Name three ways that isotopes are the same.
1) number of protons
2) number of electrons
3) chemical behavior
The total number of protons and neutrons can also be called the ______.
mass number
What does amu stand for?
atomic mass unit
The unit amu is based on which isotope?
carbon-12
Identify the mass in amus for the proton, neutron, and electron
proton = 1 amu
neutron = 1 amu
electron = 0 amu
List three types of electromagnetic radiation.
gamma rays, X-rays, UV rays
List the one thing that all waves have in common.
They all travel at the speed of light. (3.00 *10^8 m/s)
List three ways that waves are different.
1) wavelength
2) frequency
3) energy
Describe the difference between frequency and wavelength.
wavelength- the distance between equivalent points on adjacent waves

frequency- the number of waves that pass a given point in one second

Wavelength and frequency are related ________.
indirectly
Energy and frequency are related _________.
directly
Who first came up with the idea that energy was emitted as particles not as waves?
Planck
Einstein came up with the dual __________-___________ nature for electromagnetic radiation.
dual wave-particle nature.
What is a photon?
a particle of electromagnetic radiation carrying a quantum of energy
Describe how an electron moves from ground state to excited state and back to ground state.
An electron in its lowest energy state is in its ground state, when it absorbs energy it moves to an excited state, it gives off a photon and moves back to ground state.
What is released when an electron moves from excited state to ground state?
a photon
What is the difference between ground state and excited state?
ground state- lowest energy level
excited state- higher energy level
Each atom has its own ___________ ________________ ______________ that can be used to identify the element, much like a fingerprint.
atomic emission spectrum
How did Bohr describe the movement of electrons?
moved around the nucleus in organized orbits like planets orbit around the sun
The further the electron is away from the nucleus the ( more / less ) energy it has.
more
What is the difference between absorption and emission?
absorption- taking in energy
emission- giving off energy
What three scientists contributed to the current Quantum Model of the Atom?
de Broglie, Heisenberg, Schrodinger
What is predicted by the Schrodinger equation?
the probability of finding an electron in a given orbital
State the Heisenberg Uncertainty Principle
The position and velocity of an electron cannot be determined simultaneously.
What is an atomic orbital?
a region of space where an electron is likely to be found
How many energy levels are possible in an atom?
7
Each energy level contains sub levels. What are the four sub-levels and their shapes?
1) s -sphere
2) p -dumbbell
3) d -4 leaf clover
4) f -complicated
Each sub-level contains orbitals. How many orbitals are in each type of sub-level?
s-1
p-3
d-5
f-7
How many electrons are required to fill the first energy level?
2
How many electrons can go into the third energy level?
18
What information can be determined from the description 5s^2?
electrons are located in the 5th energy level in a spherical shaped sub-level and there are 2 electrons present.
How is a nuclear equation different from a chemical equation? (give at least two differences)
nuclear equations- change atoms from reactant to product; give off large amounts of energy

chemical equations- atoms stay the same from reactant to product; give off small amounts of energy

What are the main subatomic particles involved in a chemical equation?
electrons
What are the main subatomic particles involved in a nuclear equation?
protons and neutrons
Which type of reaction, chemical or nuclear, give larger releases of energy?
nuclear
What are the three types of radiation?
alpha, beta, and gama
Rank the three types of radiation from most massive to least massive.
alpha, beta, gamma
Rank the three types of radiation from most penetrating to least penetrating.
gamma, beta, alpha
How did Rutherford determine that there were three types of radiation?
placed a positive and negative plate above and below a radioactive substance; beta was attracted to the positive plate, alpha was attracted to the negative plate, and gamma was unaffected
What was Roentgen’s contribution to nuclear chemistry?
developed the X-ray
What was Becquerel’s contribution to nuclear chemistry?
determined that radioactive substances spontaneously give off radiation
What was the Curie’s contribution to nuclear chemistry?
isolated radium and plonium
Cobalt-60 has a half-life of 5.27 years. How much of a 165g sample remains after 26.35 years?
5.16 g
How are fission and fusion similar?
fission and fusion are both nuclear processes.
How are fission and fusion different?
fission- splitting of a large atom to release energy
fusion- joining of smaller atoms to release energy
What are the only two fissionable isotopes?
uranium and polonium
How is fission a chain reaction?
fission begins when a neutron hits an unstable uranium atom. When this reaction is complete, 3 neutrons are given off allowing the reaction to continue.
How is the speed of the fission reaction controlled in a nuclear reactor?
by using control rods to absorb neutrons and slow down the reaction
The reactor heats the water which generates steam. The steam turns the _____ which generates _____.
turbine; electricity
What is the only substance that produces energy from fusion?
the sun
What are the current limitations that are keeping us from using fusion as a main power source?
temperature required is very high; also, we have to develop a container to hold this extremely high temperature.
What is a spent fuel rod?
a rod that use to contain fissionable uranium atoms, but has used all the uranium
What is done with the spent fuel rods after they are removed from the nuclear reactor?
they are put in spent fuel pools (swimming pools)
What are some benefits to using nuclear reactors to make energy compared to other methods?
cheap, release no harmful gases into atmosphere, easy to do
What are some drawbacks to using nuclear reactors to make energy compared to other methods.
give radioactive product that must be stored, plants are expensive to build
What is the unit used to measure the dose of radiation absorbed by humans?
rem
What are three methods used to detect radiation?
film bodge, Geiger counter
List 5 uses of nuclear chemistry.
bombs, X-rays, cancer treatment, to make energy, smoke detectors
______ came up with arranging the elements in order of their repeating properties. He arranged the elements in order of increasing atomic mass.
Mendeleev
_______ later revised the periodic table by arranging the elements in order of increasing _____ ________.
Moseley; atomic number
State the periodic law.
when the elements are arranged in order of increasing atomic number their properties will repeat.
What is the name of group 1 elements?
Alkali metals
What is the name of group 2 elements?
Alkaline Earth metals
What is the name of group 17 elements?
Halogens
What is the name of group 18 elements?
Noble Gases
What is the name of groups 3-12?
transition metals
What are the names of the two rows that make up the f-block?
Lanthanides and Actinides
What are metalloids? Where are they located on the periodic table?
substances that have properties of both metals and nonmetals
List three properties of metals. Where are they located on the periodic table?
good conductors, malleable, ductile; to the left of the stair-step line
list three properties of nonmetals. Where are they located on the periodic table?
bad conductors, not malleable, brittle; right of the stair-step line
List three properties of s-block metals.
soft, very reactive, good conductors
List two properties of p-block metals.
harder than s-block metals, not as reactive as s-block metals
list four properties of d-block metals.
shinny, good conductors, hard, malleable
Explain why group 18 is referred to as the noble gases?
because their outer energy level is full and they do not interact (bond) with any other elements
Explain what the atomic radius measures.
distance from nucleus to edge of electron cloud
How is the atomic radius of an atom actually measured?
distance between 2 nuclei divided by 2
What is the period trend or the atomic radius? The group trend?
period trend= decreases to the right
group trend= increases going down
Rank the following elements from largest radius to smallest radius: Cl, I, Br, C, F, Li
I, Br, Cl, Li, C, F
What is the group trend for ionic radius?
increases as go down groups
What is the difference between a cation and an anion? Include how each is formed.
-cation is a positive ion that forms when electrons are lost
-anion is a negative ion that forms when electrons are gained
What is the period trend for ionization energy? The group trend?
period: increases to the right
group: decreases going down
What is ionization energy?
the energy required to remove an electron from an atom
When an electron is removed from an element a ( cation / anion ) is formed. Are metals or nonmetals more likely to do this?
cation; metals
What is electronegativity?
the attraction for electrons in a chemical bond
What is the most electronegative element?
fluorine
Why do elements bond?
to become stable
What electrons are involved in the bonding process?
valence electrons
What types of elements are combined in a compound? what type of bonding? List one example of a compound.
metal and nonmetal; ionic; NaCl
List three properties of ionic compounds.
high melting point, conduct when liquid, brittle
What is the overall charge of ionic compounds?
zero (neutral)
How are ionic bonds formed?
metal cation is attracted to a nonmetal anion
Why can ionic compounds not conduct electricity in the solid state?
because the anions are not free to move; surrounded by cations
What is a cation? Give an example.
an ion with a positive charge
Ex: Mg 2+
What is an anion? Give an example?
An ion with a negative charge.
Ex: O2-
Why, when writing the name of a compound that contains a transition metal, does a Roman numeral have to be included?
Because transition metals do not always form the same ion; the correct one is indicated with a Roman numeral
What is a binary compound? All binary compounds, whether ionic or covalent, will end with what suffix?
a combination of 2 elements; will end with -ide
What is a polyatomic ion?
an ion composed of more than one atom.
What is the term used in metallic bonding that describes the fact that electrons do not belong to one particular atom?
delocalized electrons
Why are electrons delocalized in metals?
because the outer energy levels overlap
Why are metals good conductors of heat and electricity?
because the delocalized electrons are free to move
Why are metals shiny?
because delocalized electrons are free to move
What types of elements are combined in a molecule? what type of bonding? List one example of a molecule.
nonmetal and nonmetal; covalent; CO2
What is a diatomic molecule?
a molecule containing 2 atoms
EX: Cl2 or CO
Which bonds are stronger, ionic or covalent?
ionic
What would melt first, a block of ice or a grain of salt? Why?
block of ice; ice is covalent and salt is ionic; because ionic is stronger than covalent, covalent will melt first
How many electrons are shared in a single bond?
two
How many electrons are shared in a double bond?
4
How many electrons are shared in a triple bond?
6
Rate single, double, and triple bonds from longest to shortest. From strongest to weakest.
longest-shortest: single, double, triple
strongest-weakest: triple, double, single
What is the difference between a lone pair of electrons and a shared pair of electrons?
lone pair belong only to one atom, shared pair is shared between two atoms
State the octet rule
each atom will lose, gain, or share to achieve 8 electrons in their outer energy level
What are the two exceptions to the octet rule?
Hydrogen and helium (they only want 2, not 8)
What three things must be checked in order for a Lewis structure to be correct?
total number of electrons, octet rule, used correct number of atoms
Lewis structures represent molecules in 2D, in order to represent molecules in 3D what theory must be used?
VSEPR theory
What is the VSEPR theory?
describes the 3D arrangement of atoms in a molecule
When assigning variables to molecules in order to determine the VSEPR shape, what does A represent? What does B represent? what does E represent?
A- central atom
B- atoms bonded to central atom
E- lone pairs of electrons on the central atom
Why do the trigonal planar and bent shapes have bond angles less than 109.5??
because more than one correct lewis structure can be drawn
Polar bonds and nonpolar bonds are the two types of covalent bonds. How are they different? Give an example of each.
polar bonds- electrons shared unequally (partial charges present) EX: H-F
nonpolar bonds- electrons shared equally (no partial charge present) EX: O-O
How is an intermolecular force different from an ionic or covalent bond?
intermolecular forces occur between molecules; intro molecular forces (ionic and covalent) occur within molecules
List three types of intermolecular forces
dispersion, dipole, hydrogen bonding
How can you determine the strength of a covalent bond?
electronegativity difference
Hydrogen bonding occurs when hydrogen bonds to which 3 elements?
F, O, N
London dispersion forces exist between ________ molecules.
all
Dipole-dipole forces exist only between _____ molecules.
polar
Why are partial charges used in polar molecules?
there is an unequal distribution of electrons
How is it determined which atom in the bond gets the partial negative charge?
the more electronegative atom gets the partial negative.
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