Chapters 4 and 5 Study Guide

energy of a photon

(E)photon=hv (E)photon represents energy h is Planck's constant v represents frequency

energy of quantum

(E)quantum=hv (E)quantum represents energy h is Planck's constant v represents frequency

Aristotle

-empty space cannot exist -matter is made of earth, fire, air, and water

Democritus

-greek philosopher -first person to propose the idea that matter was not infinitely divisible -matter is composed of atoms, which move through empty space -different kinds of atoms have different sizes and shapes -size, shape, and movement of atoms determine the properties of matter -matter is made up of tiny particles called atomos (atom derived from this term)

Dalton

-matter is composed of extremely small particles called atoms -atoms are indivisible and indestructible -atoms of a given element are identical in size, mass, and chemical properties -atoms of a specific element are different from those of another element -different atoms combine in simple whole-number ratios to form compounds -in a chemical reaction, atoms are separated, combined or rearranged

Dalton's atomic theory

1) elements are composed of atoms 2) atoms of same element are identical, but differ from other elements 3) elements can mix together 4) atoms only change when mixed with other elements

quantum number

Bohr assigned a number, n, called the _____ _____, to each orbit. he also calculated the radius of each orbit.

mass of isotopes

____ containing more neutrons have a greater mass. in spite of these differences, isotopes of an atom have the same chemical behavior. as you will read later in this textbook, chemical behavior is determined only by the number of electrons an atom has.

electromagnetic radiation

a form of energy that exhibits wavelike behavior as it travels through space ex: microwaves

gamma ray

a high-energy radiation that possesses no mass and is denoted by the symbol of an upside down y. because they are neutral, gamma rays are not deflect by electric or magnetic fields. they usually accompany alpha and beta radiation, and they account for most of the energy lost during radioactive decays. this term is massless

photon

a massless particle that carries a quantum of energy; proposed by Einstein

nuclear reaction

a reaction that involves a change in an atom's nucleus is called this.

proton

a subatomic particle carrying a charge equal to but opposite that of an electron; that is, a ____ has a chagre of 1+.

neutron

a subatomic particle that has a mass nearly equal to that of a proton, but it carries no electric charge.

nucleus

almost all of its mass were contained in a tiny, dense region in the center of the atom; the negatively charged electrons held within the atom by their attraction to the positively charged nucleus. incredibly dense. contains positively charged particles called protons

beta particles

an electron with a 1- charge. the negative charge of the beta particle explains why it is attracted to the positively charged plate.

nuclear equation

an equation that shows the atomic numbers and mass numbers of the particles involved. the mass number is conserved in nuclear equations

scanning tunneling microscope (STM)

an instrument that allows individual atoms to be seen

isotope abundances

analyzing an element's mass can indicate the most abundant isotope for that element. for example, fluorine (F) has an atomic mass that is extremely close to 19 amu. if fluorine had several fairly abundant isotopes, its atomic mass would not likely be so close to a whole number. thus, you might conclude that all naturally occurring fluorine is probably in the form of fluorine-19.

what was wrong about Dalton's theory

atoms are divisible and atoms of the same element can have slightly different masses

isotopes

atoms with the same number of protons but different numbers of neutrons are called this.

electromagnetic wave relationship

c=yv c is the speed of light in a vacuum y is the wavelength v is the frequency

mass of an electron

calculated by knowing the electron's charge and using the known charge-to-mass ratio. the following equation shows how small the mass of an electron is: mass of an electron=9.1x10^-28g=1/1840 the mass of a hydrogen atom

alpha particle

contains two protons and two neutrons, and thus has a 2+ charge, which explains why alpha particles are attracted to the negatively charged plate. an ____ _____ is equivalent to a helium-4 nucleus

electromagnetic spectrum

continuous range of wavelengths and frequencies. colors that can be separated from white light (prism effect); includes all forms of electromagnetic radiation, with only differences in the types of radiation being their frequencies and wavelengths.

what was one downside of rutherford's model?

could not account for all of the atom's mass

Robert Milikan

determined the charge of an electron using the oil-drop apparatus. X-rays knock out electrons from the air particles between the two parallel charged plates and the electrons stick to the droplets, giving them a negative charge. by varying the intensity of the electric field, Millikan could control the rate of a droplet's fall. he determined the magnitude of the charge on each drop increased in discrete amounts and determined that the smallest common denominator was 1.602 x 10^-19 coulombs. he identified this number as the charge of the electron. this charge was later equated to a single unit of negative charged noted 1-: a single electron carries a charge of 1-

J.J. Thomson

did a series of cathode-ray tube experiments at Cambridge University in the late 1890s to determine the ratio of its charge to its mass; identified the first subatomic particle: the electron

isotope notation

each isotope of an element is identified with a number called the mass number

principal energy level

each major energy level is called a ___ ____ ____. an atom's lowest ___ __ ______ is assigned a principal quantum number of 1. when the hydrogen atom's single electron occupies an orbital with n=1, the atom is in its ground state. up to 7 energy levels have been detected for the hydrogen atom, giving n values ranging from 1 to 7

photoelectric effect

electrons, called photoelectrons, are emitted from a metal's surface when light of a certain frequency, or higher that a certain frequency, shines on the surface

Rutherford's model

expected the light alpha particles to pass through gold atoms. he expected only a few of them to be slightly deflected. a narrow beam of alpha particles was aimed at a thin sheet of gold foil. a zinc-sulfide-coated screen surrounding the gold foil produced a flash of light when struck by an alpha particle. by noting where the flashes occured, the scientists could determine if the atoms in the gold foil deflected the alpha particles. the results: a beam of alpha particles bombarded a thin gold foil. most of the alpha particles went through the gold foil. however, a few of them bounded back, some at large angles while some deflected straight back toward the source; proved the plum pudding model wrong.

charge-to-mass ratio

found by measuring the effects of both magnetic and electric fields on a cathode ray; J.J. Thomson figured this out and compared the ratio to other known ratios and concluded that the mass of the charged particle was less than hydrogen, the lightest known atom, which meant there were particles smaller than the atom, meaning atoms were divisible

Planck's constant

has a value of 6.626x10^-34 Jxs, where J is the symbol for joule, the SI unit of energy. the equation shows that the energy of radiation increases as the radiation's frequency, v, increases. according to this theory, for a given frequency, v, matter can emit or absorb energy only in whole-number multiples of hv

wavelength

is the shortest distance between equivalent point on a continuous wave

mass number

is the sum of the atomic number (or number or protons) and neutrons in the nucleus ______=atomic number + number of neutrons

plum pudding model

made by J.J. Thomson made this model which states that the atom is a uniform, positively charged sphere containing electrons

law of conservation of mass

matter is not created nor destroyed in any chemical or physical change; Dalton's atomic theory easily explains that this law in chemical reactions is the result of the separation, combination, or rearrangement of atoms- atoms that are not created, destroyed, or divided in the process

natural abundance of isotopes

most elements are found as mixtures of isotopes. usually, no mater where a sample of an element is obtained, the relative abundance of each isotope is constant

electrons

negatively charged particles that are part of all forms of matter are now known as this term.

what is the charge of matter

neutral

oil-drop apparatus

oil is sprayed into the chamber above the two parallel charged plates. the top plate has a small hole through which the oil drops. X-rays knock out electrons from the air particles between the two parallel charged plates and the electrons stick to the droplets, giving them a negative charge. by varying the intensity of the electric field, Millikan could control the rate of a droplet's fall.

principal quantum number (n)

one of the four quantum numbers to atomic orbital; indicates the relative size and energy of atomic orbitals. as n increases, the orbital becomes larger, the electron spend more time farther from the nucleus, and the atom's energy increases. therefore, n specifies the atom's major energy level

atomic mass unit (amu)

one-twelfth the mass of a carbon-12 atom

cathode-ray tube

people wanted to explore the connection between matter and electric charge. scientists wondered how electricity might behave in the absence of matter. this newly invented vacuum pump passed electricity through glass tubes from which most of the air had been removed. metal electrodes are located at the opposite ends of the tube. the electrode connected to the negative terminal of the battery is called the cathode, and the electrode connected to the positive terminal is called the anode. when voltage is applied, electricity travels form the cathode to the anode

de Broglie equation

predicts that all moving particles have wave characteristics. it also explains why it is impossible to notice the wavelength of a fast-moving car.

energy sublevel

principal energy levels contain this term; principal energy level 1 consists of a single sublevel, principal energy level 2 consists of two sub levels, principal energy consists of three sublevels, and so on.

Einstein

proposed that light has a dual nature. a beam of light has wavelike and particle-like properties. it can be thought of as a beam of bundles of energy called photons. he also proposed that the energy of a photon must have a certain threshold value to cause the ejection of a photoelectron form the surface of the metal. thus, even small number of photons with energy above the threshold value will cause the photoelectric effect

Planck

proposed that the energy emitted by hot objects was quantized. he then went further and demonstrated mathematically that a relationship exists between the energy of a quantum and the frequency of the emitted radiation

nuclear stability

ratio of protons to neutrons; if not equal they lose energy through radioactive decay

shapes of orbitals

s: spherical p:dumbbell-shaped not all d or f orbitals have the same shape. each orbital can contain, at most, two electrons.

radioactivity

scientists noticed in the late 1890s that some substances spontaneously emitted radiation in a process they named this.

Jame Chadwick

showed that the nucleus also contained another subatomic neutral particle called the neutron; won a nobel prize for proving the existence of neutrons

Heisenberg uncertainty principle

states that it is fundamentally impossible to know precisely both the velocity and position of a particle at the same time

Rutherford

studied how positively charged alpha particles (radioactive particles) interacted with solid matter. this scientist conducted an experiment to see if alpha particles would be deflected as they pass through a thin gold foil. considering the properties of the alpha particles and the electrons, and the frequency of the deflections, he calculated that an atom consisted mostly of empty space through which electrons move. he also concluded that almost all of its mass were contained in a tiny, dense region in the center of the atom, which he called the nucleus.

atomic emission spectrum

the ____ ____ ____ of an element is the set of frequencies of the electromagnetic waves emitted by atoms of the element

atomic mass

the _____ ____ of an element is the weighted average mass of the isotopes of that element, b/c isotopes have different masses, the weighted average is not a whole number

amplitude

the _____ of a wave is the wave's height from the origin to a crest, or from the origin to a trough. wavelength and frequency do not affect the _____ of the wave

quantum mechanical model of an atom

the atomic model in which electrons are treated as waves is called the wave mechanical model of the atom, also known as this term. this model limits an electron's energy to certain values. different from bohr's model, the quantum mechanical model makes no attempt to describe the electron's path around the nucleus

ground state

the lowest allowable energy state of an atom is called this. when an atom gains energy, it is said to be in an excited state

quantum

the minimum amount of energy that can be gained or lost by an atom

atomic number

the number of protons in an atom is referred to as this _____=number of protons=number of electrons

frequency

the number of waves that pass a given point per second. one hertz, the SI unit of _____, equals one wave per second

alpha radiation

the radiation that was deflected toward the negatively charged plate was named this. it is made up of alpha particles

beta radiation

the radiation that was deflected toward the positively charged plate was named this. this radiation consists of fast-moving beta particles

radiation

the rays and particles emitted by the radioactive material were called this

why did the deflections occur in rutherford's model?

the repulsive force produced between the positive nucleus and the positive alpha particles cause the deflections

atom

the smallest particle of an element that retains the properties of the element is called this.

atomic orbital

the wave function predict a three-demensional region around the nucleus called this, which describes the electron's probable location. this term is like a fuzzy cloud in which the density at a given point is proportional to the probability of finding the electron at that point

cathode ray

there is a ray (radiation) going through a tube in the cathode-ray tubes. the accidental discovery of this term led to the invention of television. _____ ____ are a stream of charged particles; the particles carried a negative charge (the exact value of the negative charge was not known); these negative rays are found in all forms of matter

Bohr's model of the atom

this model was created because scientists did not understand the relationships among atomic structure, electrons, and atomic emission spectra. this danish physicist working in Rutherford's laboratory in 1913, proposed a quantum model for the hydrogen atom that seemed to answer why atomic emission spectra of elements is discontinuous rather than continuous?

Sir William Crookes

this scientist noticed a flash of light within one of the cathode-ray tubes. a green flash was produced by some form of radiation striking a zinc-sulfide coating that had been applied to the end of the tube. further worked showed that there was a ray (radiation) going through a tube.

how does the cathode-ray tube work?

this vacuum pump passed electricity through glass tubes from which most of the air had been removed. metal electrodes are located at the opposite ends of the tube. the electrode connected to the negative terminal of the battery is called the cathode, and the electrode connected to the positive terminal is called the anode. when voltage is applied, electricity travels form the cathode to the anode. a tiny hole located in the center of the anode produces a thin beam of electrons. a phosphor coatinf allows the position of the beam to be determined as it strikes the end of the tube. to things can then happen: (a) b/c the cathode ray is deflected in a magnetic field, the particles in the ray must be charged or (b) b/c the cathode ray is deflected toward the positively charged plate by an electric field, the particles in the ray must have a negative charge

radioactive decay

unstable nuclei lose energy by emitting radiation in a spontaneous process called this, and do so until they form stable atoms, often a different element

hydrogen line spectrum

when an electron drops from a higher-energy orbit to a lower-energy orbit, a photon is emitted. the ultraviolet (Lyman), visible (Balmer), and infrared (Paschen) series correspond to electrons dropping to n=1, n=2, and n=3, respectively

particle electromagnetic-wave relationship

y=h/mv y represents wavelength h is Planck's constant m represents mass of the particle v represents velocity