Exam 3 Flashcards
Chapters 12-14
True or False: atoms are the building blocks of nature
true
how many distinct kinds of atoms have been found to date?
118 (90 of which are in nature)
What is an element?
any material consisting of only one type of atom
Atoms consist of ____________, ___________, and ____________.
protons, neutrons, and electrons
All atoms of the same element have the same number of protons. Which is called the ________ ____________.
Atomic Number
The mass of an atom in __________ ______ ________ (amu) is the total number of protons and neutrons in the atom.
atomic mass units
What are isotopes?
atoms of the same element that have different masses (numbers of neutrons)
What is the periodic table of elements?
A highly organized listing of all known elements sorted by groups (columns) and periods (rows).
How is the position of an element determined?
The position of an element is determined by its atomic number and what type of element it is: metals, non-metals, and metalloids.
What are the four sections of the periodic table, and what groups do they encompass?
Main group: groups 1, 2, 14-18
Transition Metals: Groups 3-13
Inner-transition metals: two rows under the main pt
Where are Alkali metals found?
Group 1
Where are Alkaline earth metals found?
Group 2
Where are halogens found?
Group 7 (technically 17)
Where are noble gasses found?
group 8 (technically 18)
Describe metals
- good conductors (bad insulators) of heat and electricity
- typically shiny
- malleable and ductile
- solids at room temperature, with the exception of mercury (liquid at room temp)
Describe nonmetals
- properties are more variable
- solids, liquids, and gases
- poor conductors (good insulators) of heat and electricity
describe metalloids
- dull appearing
- brittle
- solids
- sometimes called semiconductors
What is a spectroscope?
an instrument that separates and spreads light into its component frequencies
what does a spectroscope allow for?
analysis of light emitted by elements when they are made to glow - this identifies each element by its characteristic pattern.
Atomic Excitation: Electron _________ potential and moves farther from the nucleus. A photon of light is _________.
gains; absorbed
Atomic Excitation: Electron ________ potential energy and moves closer to the nucleus. A photon of light is _________.
loses; emitted
Describe the planetary model of the atom.
protons and neutrons are clumped together in the nucleus (the middle of the atom) with electrons orbiting around the nucleus on various levels.
Explain Electron waves
An electron’s wave nature explains why electrons in an atom are restricted to particular energy levels.
Describe the shell model of the atom
“3-D cutaway view” of an atom (think of how we draw animal cells)
In the electromagnetic force, protons _______ one another.
repel
In the nuclear forces, there is an ____________ force between protons and neutrons.
attractive
When the strong nuclear force is larger than the electric force, the protons are __________ to one another.
attracted
When the strong nuclear force is weaker than the electric force, the protons are ___________ by one another.
repelled
The presence of ___________ helps hold the nucleus together.
neutrons
What are the three types of nuclear reactions?
Radioactivity (a small piece of the nucleus leaves the atom)
Fission (“splitting the atom”)
Fusion (two small atoms combine into one larger atom)
What is Transmutation?
the conversion of one element to another element through the process of radioactive decay.
What is a half-life?
The interval of time required for one-half of the atomic nuclei of a radioactive sample to decay.
Iodine-131 has a half-life of 8 days. If you start with 1000g of iodine-131, how much will be left after 32 days?
8 days = 500g
16 days = 250g
24 days = 125g
32 days = 62.5g
What is radiometric dating?
ways of determining the age of objects or materials.
How many different radiometric dating methods are there?
Over 40; they all give good agreement
What is carbon dating used for?
plants and animals
based upon ratio of carbon-12 to carbon-14
What are nonliving things dated through?
uranium and lead isotopes
Explain ionizing radiation
knocks electrons out of atoms.
Explain Free Radicals.
An atom or group of atoms with one unpaired electron.
Explain stomatic damage
the organism exposed to the radiation is affected.
explain genetic damage
damage to reproductive system affects offspring
Most radiation we encounter is:
Natural background radiation that originates in Earth and space
What is a chain reaction?
A chain reaction is a self-sustaining reaction in which the products of one reaction event stimulate further reaction events.
Define Critical mass
the minimum mass of fissionable material in a reactor or nuclear bomb that will sustain a chain reaction.
At or above critical mass, in a large quantity of atoms, an enormous __________ can occur.
explosion
What is the Mass-Energy Equivalence?
E=mc^2
mass is a very large form of pe.
Mass pe can be converted to ke.
Produce ________ = used to produce electricity in nuclear reactors/
steam
Nuclear reactors: what fuels are/can be used?
Uranium-235
Plutonium-239
What does a control rod do?
absorbs extra neutrons to slow down acceleration.
In nuclear reactors, nuclear explosion cannot occur because fuel pellets are below critical mass. In a nuclear bomb, two __________ masses are driven together to reach critical mass.
subcritical
Only ______% of natural Uranium is U-235
0.7%
Define Nuclear Fusion
the combination of nuclei of light atoms to form heavier nuclei with the release of much energy
________ is the “nuclear sink” for energy production. Any nuclear transformation that moves nuclei towards iron releases _______.
iron; energy
Describe thermonuclear fusion
nuclear fusion is produced by high temperatures.
mass decreases as energy is released.
source of energy in the starts (sun).
What is a problem of fusion power plants?
They have really high temperatures (laser?).
Only experimental at this time.
What are the two advantages of Fusion Power Plants?
Hydrogen (from water) is the fuel source and there is low levels of radioactivity.
Define a physical property:
A physical property describes the look or feel of a substance.
Define a chemical property:
A chemical property describes the tendency of a substance to transform into a new substance.
What are the 5 signs of a chemical reaction?
Change in color
Precipitation
Bubbling (not boiling)
Change in temp.
Evolution of light
What is an element?
A material made of only one kind of atom.
What is the elemental formula?
The elemental formula is used to show the proportion by which atoms combine to form an element.
What is a compound?
A substance consisting of atoms of different elements.
____________ have properties uniquely different from the elements from which they are made.
Compounds
What is a chemical formula?
A chemical formula is used to show the proportion by which elements combine to form a compound.
Are these elements or compounds?
1. Cl2
2. H2O
3. CCl4
4. C60
5. PBr3
- element
- compound
- compound
- element
- compound
What is the first guideline to naming compounds?
Used when elements are on opposite sides of the periodic table (a metal and a nonmetal). Start with the element farthest to the left in the periodic table, then, for the element to the right, add the suffix -ide.
Name this compound: NaCl
Sodium Chloride
Name this compound: KF
Potassium flouride
Name this compound: CaBr2
Calcium Dibromide
Name this compound: BaO
Barium oxide
Name this compound: Cs2S
Dicesium sulfide
What is the second guideline to naming compounds?
Used when both elements are on the same side of the periodic table (usually both are nonmetals). With different possible combinations of elements, use prefixes to remove ambiguity.
What are the five prefixes used for guideline 2?
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
Name this compound: CO
Carbon monoxide
Name this compound: CO2
Carbon dioxide
Name this compound: CCl4
Carbon tetrachloride
Name this compound: NO2
Nitrogen dioxide
Name this compound: PBr3
Phosphorus tribromide
Name this compound: N2O4
Dinitrogen tetroxide
What is the third guideline for naming compounds?
Name is not systematic. It is a “common name”.
Name this compound: H2O
“Water”
dihydrogen monoxide
Name this compound: H2O2
“Hydrogen Peroxide”
dihydrogen dioxide
