Chemistry Test: Chapter 3 + Part of Chapter 4
Cathode rays are composed of _____.
Electrons.
Which particle has the least mass?
Electrons.
According to Rutherford's experiment, the atom is composed largely of ______.
Empty Space
What is the Wave Theory?
It predicted that any frequency could supply enough energy to eject a electron.
What is the Photoelectric Effect?
It refers to the emission of electrons from a metal when light shines on the metal.
A chemical compound always has the same elements in the same proportions by mass regardless of the source of the compound. This is a statement of ____________.
Law of Definite Proportions
Low Frequency = ______ Wavelength.
Long
There are ____ possible excited states, but only ___ ground state.
Many; One
An electron has a large charge to ____ ratio.
Mass
What is the Law of Conservation of Mass?
Mass is neither created nor destroyed.
Who used charge/mass to determine the mass of electrons 1/2000th the mass of an H atom.
Milliken
What is an electron?
Negatively charged and large compared to the nucleus.
What did Einstein call these particles?
Photons
How are the energy and frequency of electromagnetic radiation related?
Planck's constant X frequency = energy
How are the energy and wavelength of electromagnetic radiation related?
Planck's constant X speed of light / wavelength = energy
What is Thomson's model called?
Plum Pudding Model
If the charge of the alpha particle is positive, what is the charge of the nucleus?
Positive
What are the subatomic particles?
Protons, neutrons, and electrons.
Which subatomic particle has a charge of +1?
Protons.
List the colors of light in the visible light spectrum in order of increasing frequency.
Red, orange, yellow, green, blue, indigo, violet.
Summarize Rutherford's model of the atom, and explain how he developed this model based on the results of his famous gold-foil experiment.
Rutherford shot alpha particles at a sheet of gold and expected them to pass right through it. They ended up scattering in all directions. This led him to believe that there must be a very dense positively charged atom in the nucleus.
High Frequency = _______ Wavelength.
Short
What is quanta?
Small packets of energy.
Bohr's model did not explain what?
Spectra of atoms with more than one electron or the chemical behavior of atoms.
What else did Thomson discover?
That atoms can be divided into sub-atomic particles.
What did JJ Thomson discover?
That cathode ray particles carry a negative charge. These negatively charged particles are deflected from their straight line path when an electric field is applied.
What was Rutherford's explanation for the results of his experiment?
That the deflected alpha particles must experience a powerful force within the atom.
All of those combined form what?
The Electromagnetic Spectrum
Describe JJ Thomson's model.
The atom is composed of diffuse balls of positive charged with negative particles dispersed throughout. .
What number uniquely identifies an element?
The atomic number.
What was the first sub-atomic particle to be discovered?
The electron.
What did Planck study?
The emission of light by hot objects.
Distinguish between the ground state and an excited state of an atom.
The ground state is the lowest energy level available. An excited state is a higher energy level.
What is ground state?
The lowest energy state of an atom.
What is a quantum of energy?
The minimum quantity of energy that can me lost or gained by an atom.
What did Rutherford discover?
The nucleus.
What is an atom?
The smallest particle of an element that retains them chemical properties of that element.
True / False: Aristotle had no experimental evidence.
True, Aristotle had no experimental evidence.
True / False: Democritus had no experimental evidence.
True, Democritus had no experimental evidence.
True / False: Each particle of light carries a quantum of energy.
True, each particle of light carries a quantum of energy.
True / False: Not all proportions of Dalton's theory were correct.
True, not all proportions of Dalton's theory were correct.
What is the small portion of the electromagnetic system that can be seen by the human eye (400nm-700nm) called?
Visible Spectrum
Before 1900, scientist thought light behaved only as a ____. Then they discovered that light has ________-____ characteristics.
Wave; Particle-like
According to Bohr's model of the hydrogen atom, how is hydrogen's emission spectrum produced?
When an electron falls from a higher to a lower orbit (energy level) energy is given off (orbit). The different orbits produce fixed lines in the emission spectrum of hydrogen.
What kind of radiation is visible light?
electromagnetic radiation
An important result of Rutherford's experiments what gold foil was to establish that _____.
electrons have a negative charge
Which theory of light- the wave of particle theory -best describes this phenomena: the emission of electromagnetic radiation by an excited atom.
particle
Which theory of light- the wave of particle theory -best describes this phenomena: the photoelectric effect.
particle
Which theory of light- the wave of particle theory -best describes this phenomena: the interference of light.
wave
How are wave length and frequency of electromagnetic radiation related?
wave length X frequency = speed of light
What does "atom" mean?
"atomos"- indivisible
Which parts of Dalton's theory were correct?
#1 and #2
What was Dalton's theory?
1. All matter is composed of atoms. 2. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. 3. Atoms cannot be subdivided, created, or destroyed. 4. Atoms of different elements combine in simple whole-number ratios to form compounds. 5. In chemical reactions, atoms are combined, separated, or rearranged.
Describe at least four properties of electrons that were determined based on the experiments of Thomson and Millikan.
1. Electrons are negatively charged particles. 2. Electrons are present in all atoms of all elements. 3. Electrons have a very large charge to mass ratio. 4. Electrons have a mass of 9.109 X 10^-31 Kg
What is a photon?
A particle of electromagnetic radiation having zero mass and carrying a quantum of energy.
What is the name of Dalton's theory?
Atomic Theory of Matter
What are elements made of?
Atoms
What are compounds made of?
Atoms of different elements.
In the early twentieth century, what two experiments involving light and matter could not be explained by the wave theory of light?
1. Photoelectric Effect 2. Emission Spectrum of the Hydrogen Atom
What did Bohr's model tell us?
1. The electron can circle the nucleus only in allowed paths. 2. Lowest energy state- orbit closest to the nucleus. 3. Orbit separated from nucleus by large empty space where electron cannot exist. 4. Energy of electron is higher when an electron is in orbits that are successively farther from the nucleus.
How many alpha particles deflected back toward the source?
1/8000
All atoms consist of how many regions?
2
Who was Democritus?
A Greek philosopher
What is electromagnetic radiation?
A form of energy that exhibits wavelike behavior as it travels through space.
What two regions make up the atom?
A nucleus and an electron.
What is a nucleus?
A small region located at the center of an atom; contains protons (+) and neutrons (0).
What shape did Dalton think an atom was?
A sphere.
What is Excited State?
A state in which an atom has a higher potential energy than it has in its ground state.
What is a chemical reaction?
A transformation of a substance(s) into 1 or more new substances.
According to the Law of Conservation of Mass, if element A has an atomic mass of 2 mass units and element B has an atomic mass of 3 mass units, what mass would be expected for compound AB? for compound A2B3?
AB = 5 A2B3 = 13
Which philosopher did not believe in atoms?
Aristotle
Why was Rutherford's model incomplete?
Because it did not explain how an atom's electrons were distributed in space surrounding the positively charged nucleus.
In 1913 ____ proposed H atom model- linked electrons to photon emission.
Bohr
Describe two major shortcomings of Bohr's model of the atom.
Bohr's model only explained the hydrogen atom, not atoms with more than one electron. It also did not explain the chemical behavior of atoms.
What experiment is evidence that atoms are divisible?
CRT experiment
What is the Law of Definite Proportions?
Chemical compounds contain the same elements in exact proportions regardless of sample size.
What is the Law of Multiple Proportions?
Compounds composed of elements in ratios of small whole numbers.
Aristotle thought all matter was __________.
Continuous
Who turned Democritus' ideas into a scientific theory?
Dalton
Explain: The Law of Definite Proportions in terms of Dalton's Atomic Theory.
Dalton says that atoms are indivisible and indestructible.
Explain: The Law of Multiple Proportions in terms of Dalton's Atomic Theory.
Dalton says that compounds are formed by a combination of two or more different kinds of atoms.
Explain: The Law of Conservation of Mass in terms of Dalton's Atomic Theory.
Dalton says that in a chemical reaction, atoms are rearranged and are neither created nor destroyed.
Who coined the term "atom"?
Democritus
__________ radiation is absorbed only in whole numbers of photons.
Electromagnetic
When an atom returns to its ground state or a lower excited state what does it give off energy in the form of?
Electromagnetic Radiation
The range is called the ___________ _______.
Electromagnetic Spectrum
X-rays, ultraviolet light, infrared light, microwaves and radio waves are all kinds of what?
Electromagnetic radiation
What is Rutherford's experiment called?
Gold Foil Experiment
What was Rutherford's experiment?
He bombarded a thing piece of gold foil with alpha particles.
What did Rutherford assume would happen in his experiment?
He expected alpha particles to pass through with only slight deflection.
Planck proposed that ___ objects don't emit electromagnetic energy continuously but in small packets of energy called quanta.
Hot
How does electromagnetic radiation travel?
In the form of waves covering a wide range of wavelengths and frequencies.