Glossary of Chemistry Test Chapters 3 and 4

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the smallest particle of an element that retains the chemical identity of that element
Antione Lavosier's law of conservation of matter
No mass was gained or lost in the reaction. He concluded that a chemical reaction neither creates nor destroys matter, but that matter is conserved.
Law of constant Composition
He found that a given compound always contains the same elements in the same proportions by mass.
John Dalton
Atomic Theory of matter
Joseph Louis Proust
Law of Conservatipon of Composition
Atomic Theory of Matter
*Each element is composed of extrememly small particles called atoms.
*All atoms of a given element are identical, but htey differ from those of any other element.
*Atoms are neither created nor destroyed in a chemical reaction.
*A given compound always has the same relative numbers and kinds of atoms.
Michael Faraday
Atoms contain particles that have electrical Charge.
What does the word static mean?
Benjiman Franklin
An atom could have one of two different electrical charges. Either posative (+) or negative (-)
Cathode Ray
A stream of particles that are originated from a cathode. These particles are negativley charged.
Matter is neither created nor destroyed in chemical reactions
All matter is composed of tiny invisible particles.
A civen compound always contains the same elements in the same proportions by mass
A given compound always has he same relative numbers and kinds of atoms. All atoms of a given element are identical, but they differ from those of any otehr element. Each element is composed of extremely small particles called atoms. Atoms are neither created nor destroyed in chemical reactions.
About how many elements are there in nature?
Between 100 and 113
Is it possible to see atoms using a scanning tunneling microscope?
True or False?

The submicroscopic world of an atom includes exotic particles called quarks and gluons.
Did Aristotle agree or disagree with Democratus' ideas about atoms?
What technilogical advances has the study of atoms led to
televisions and computers.
What definition of the atom is accepted by scientists today?
An atom is the smallest particle of an element that retains the identity of the element
What important contribution did Lavosier make to Dalton's atomic theory of matter?
the idea that matter cannot be created or destroyed in chemical reactions.
Why is it not necessarily true that 100% natural products are superior to those made in a labrotory?
a compound's properties come from the identity and arrangement of it's atoms, not hte place where these atoms were assembled.
What would Proust say about the composition of carbon dioxide molecules?
The mass of carbon dioxide would always be composed of a certain percentage of carbon and a certain percentage of oxygen.
What scientist suggested that the structure of the atom was somehow related to electricity?
Michael Faraday
What is the negatively charged electrode of a cathode ray tube?
Henri Bacquerel discovered radioactivity while working with a sample of which element?
Delta radiation is not a component of radiation emitted from a (1) sample
What did Rutherfords atomic scattering experamint show about hte charged nucleus of an atom?
It must be posative
What did Thomson conclude that the cathode rays were composed of in his experiment with cathode ray tubes?
negatively charged particles.
static electricity
electrical charges that are not in motion
SI unit of electrical charge; charge of one electron
spontaneous emission of radiation from an element.
Negatively charged particle found outside the atomic nucleus
gamma radiation
radiation that is similar to X- Rays and is not composed of particles
Atomic Nucleus
Small core at the center of an atom containing a positive charge
alpha particle
particle with a 2+ charge that is emitted by radioactive elements.
How did Rutherford's alpha scattering experamint show that Thompson's plum pudding model of the atom was incorrect?
Alpha particles were deflected in all directions, and some were completely reversed in direction. Rutherford concluded that the particles must have bounced directly off a concentrated nucleus of posative charge.
How does Rutherford's atomic model differ from Thomson's model?
In Thomson's model the (+) and (-) charges are randomly spread throughout the electron, but Rutherford shows that the electron is mostly (-) charged empty space with a tiny (+) nucleus.
What was the purpose of Millikan's oil drop experamint?
He was trying to determine the chage of an individual electron. He was also able to calculate the mass of an individual electron.
What is the atomic number of an atom defined as?
number of protons
Static electricity comes from
charges not in motion
What are the three fundememtal particles that make up atoms?
proton, neutron, electron
What is the approximate atomic mass of a neutron in amu?
Two atoms are isotopes if htey contain...
The same number of protons but a different number of neutrons
What does an ion contain?
an unequal number of protons and electrons.
What scientist measured the charge of the electron?
Who discovered the electron?
The mass number of an atom is defined as it's...
total number of protons and neutrons
What dd Rutherford call the core of the atom?
What is an element's identity based on?
atomic number
What element is the atomic mass unit defined in terms of?
What does a cathode ray consist of?
Who discovered radioactivity?
How many protons, neutrons and electrons are in the ion (top)52, (bottom)24, Cr 3+
24 protons, 28 neutrons, 21 electrons
What are atoms composed of?
protons, neutrons and electrons
What particles are contained in the nucleus?
protons and neutrons
What charge of the nucleus do the protons carry?
Atomic mass unit
the unit used to measure the mass of protons, neutrons and electrons
Henry Moseley
found that atoms of each element contain a unique positive charge in their nucleus.
Atomic Number
The number of protons in an atom
When an atom loses or gains one or more electrons, it aquires a net electrical charge.
Atoms that have the same number of protons but different numbers of neutrons.
Mass Number
The sum of the isotope's number of protons and neutrons.
Atomic Mass
The average mass of an element's atoms which can also be called the average atomic mass of the atomic weight.
Nuclear Reactions
changes occur in an atom's nucleus that change it's composition
Strong Nuclear Force
an attractive force that holds the nucleus together. It overcomes teh electric repulsion between protons.
All atoms with an atomic number over 83 are...
radioactive decay
When an atom emits alpha, beta or gamma radiation
Nuclear Equation
an equation that keeps track of the reaction's components
Why is carbon dating not useful for artifacts made entirely of metal
The half life of most metals is too long to be useful
Compare the pnetrating power of alpha, beta and gamma radiation.
Alpha has the least penetrating power and can be easily stopped by clothign or a piece of paper. Beta particles have medium penetrating power and can be stopped by aluminum or plastic, Gamma rays have high penetrating power and can not be stopped, but can be reduced by a thick sheet of metal or concrete.
Why do nuclei need to be stable?
The neutrons hold the protons together by the strong nuclear force. If there were no neutrons the protons would repell eachother becasue htey are attracted to the neutrons.
Describe two types of nuclear reactions other than radioactive decay
Fusion; a nuclear process in which two light nuclei combine to form a single heavier one, Fission; a heavy nucleus splits in to two smaller nuclei
In any radioactive decay, the sum of the mass numbers and atomic numbers must be (1) before and after the reaction
To be stable, atoms with more than 20 protons need increasingly more...
neutrons than protons
What did De Brglie refer to thewavelike materials of particles as?
matter waves
Heisenburg's uncertainty principle
the position and the momentumof a moveing object cannot be simultaneously measured and known exactly
Which scientist labeled each enery level in his atomic model useing a quantum number
Excited state of an atom
When an electron that absorbs a quantum of energy can jump to a level of higher energy
Why is the Bohr model of an atom inaccurate?
There is no way to measure the exact path of an electron in an atom
What two properties of waves did De Broglie derive a mathematical relationship between
the mass and velocity of a moveing particla and the wavelength that it would exibit.
When Radiation is absorbed by a hydrogen electron, the hydrogen atom changes its ground state to what?
an excited state.
What color is sodium emission
Continuous spectrum
shows all wavelengths of light

outside light is a source of this
Line spectrum
a spectrum that contains only certain colors or wavelengths.

white light is a source of this
Why can't you observe the effects of wave motion for a baseball?
because it has a large mass so you need a very small wavelength
Where would hte energy level n=1 be on a Bohr atom?
the ring closest to the nucleus
What is the Ground State of an atom with energy levels n=1 through n=3? What is the Excited State?
n=1 is the ground state, n=2 and n=3 are both excited states
When an electron absorbs energy, the arrow depicting this change points (2) in relation to the nucleus
a region in space where and electron with a particular energy is likely to be found
electron density
the density of an electron cloud
Quantum Number
Number designating a principal energy level in an atom
Pauli exclusion principle
states that each orbital is an atom can hold at most, two electrons and that these electrons must have opposite signs
Quantum-mechanical model
explains the properties of atoms by treating the electron as a wave and quantizing its energy
Principal energy levels
the main energy levels in an atom
Electron Spin
The clockwise or counterclockwise motion of an electron
The electron cloud is least dense where teh probability of finding an electron is (1)
highly likely
The first principal energy level of teh hydrogen atom contains only a (1) orbital
What shape are p orbitals?
How does the 3s orbital differ from the 2s orbital?
it is larger
The number of sublevels in each principal energy level equals...
the quantum number for that energy level
Which sublevels can be found in the fourth principal energy level of an atom?
s, p, d and f
How does the quantum-mechanical model of teh atom describe electrons
by heating the electrons as a wave predicting where teh electrons will be found at all times
Explain the significance of drawing 90 pecent contour orbitals.
Because you can then see how the electrons surround the nucleus.
Give the number of orbitals and the maximum number of electrons for each sublevel: s, p, d, f
sublevel, orbitals, electrons
s, 1, 2
p, 3, 6
d, 5, 10
f, 7, 14
Light can exist as what two forms?
particles and waves
What is the brightness of light dependent on?
amplitude of the wave
What type of light can humans see?
Visible light
The number of complete waves that pass a fixed point in time per second.
What 3 types of light in the electromagnetic spectrum have the most energy?
gamma rays, x rays and UV rays
List the three types of light in the visible spectrum tat have the least energy.
red, orange, yellow
a particle of light
the amount of light energy in a wave.
What did Einstein propose about light energy after his photoelectric effect experamint?
light can act as a particle
De broglie derived a mathematical relationship between the mass and velocity of a moving particle and the (1)
Ground State
when radiation is emitted by an atom's electron and the atom's excited state is changed to the ground state.
Heisenberg's uncertainty principle
the momentum and the location of a moving electron cannot be simultaneously measured and known exactly.
S orbital
the first energy level of an atom that is shaped like a sphere
The sublevels that can be found in the third energy level of an atom are (1, 2, 3)
s, p, d
The quantum number m3 represents the (1) of an electron
magnetic spin
The sum of the superscripts in an electron configuration represents the total number of what in an atom?
Aufbau principle
Electrons are added one at a time to the lowest energy orbitals available until all the electrons of the atom have been accounted for.
The ground state is the (1) stable energy state of an atom
Hund's rule
electrons occupy equal energy orbitals so that the maximum number of unpaired electrons results.
Write the Electron configuration for magnesium and oxygen
Mg: 1s2 2s2 2p6 3s2
O: 1s2 2s2 2p4
Write the orbital diagram for aluminum
1s2 2s2 2p6 3s2 3p1
3p_^ _ _
3s_^ v
2p_ ^ v_^ v _^ v
2s_^ v
1s_^ v
What is teh speed of Light?
energy is emitted or absorbed in discreet pieces called quanta, wrote the equation E=hv, The constant, h, is equal to 6.62x10^-34 J-s
Explained the photoelectric effect in terms of quantanized energy, proposed the idea that light consists of tiny particles, or photons

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