Chemistry unit 1
Brass is a combination of a number of elements. Its exact composition can vary. A. mixture B. compound
A
Coffee is a solution of organic substances in water. A. mixture B. compound
A
A gravel can be broken down into different kinds of substances by physical processes. No chemical reactions are needed to separate different parts of gravel into pure substances. This is because gravel is a(n) A. compound B. element C. homogeneous mixture D. heterogeneous mixture
D
A particle that travels around the nucleus of an atom in orbitals is called a(n) A. quark. B. proton. C. neutron. D. electron.
D
A scientist uses an accelerator and high energy electrons to study the particles inside the protons of a helium atom. What particles is the scientist studying? A. the He neutrons B. the He nucleus C. the He electrons D. the He quarks
D
Atoms of which element contain 25 protons? A. magnesium (Mg) B. aluminum (Al) C. tin (Sn) D. manganese (Mn)
D
Bromine, a liquid at room temperature, has a boiling point of 58°C and a melting point of -7.2°C. Bromine can be classified as a A. compound. B. impure substance. C. mixture. D. pure substance.
D
Electrons orbit the nucleus in specific, defined paths. Each path has a specified energy. A. Bohr model B. electron cloud model C. Dalton model
A
If the plum pudding model of the atom was correct, what should the results of Rutherford's experiment be? A. Most of the positively charged particles should bounce back at a range of angles as they collide with the atoms in the foil; only a few should pass straight through the foil. B. Most of the positively charged particles should pass straight through the foil because they move easily through the positively charged matter in the gold atoms., C. Most of the positively charged particles should collide with the foil and stay there because they stick to the negatively charged gold atoms.
A
In which of these statements are protons, electrons, and neutrons correctly compared? A. Quarks are present in protons and neutrons but not in electrons. B. Quarks are present in protons, neutrons, and electrons. C. Quarks are present in neutrons and electrons but not in protons. D. Quarks are present in protons and electrons but not in neutrons.
A
Sports drinks contain sugar, salt, and flavorings dissolved in water. They can be made more or less sweet by adding different amounts of sugar. A. mixture B. compound
A
The chemical formula for an emerald is Be3Al2(SiO3)6. An emerald can be described as A. a pure substance because it is a compound. B. a pure substance because it is an element. C. an impure substance because it is chemically combined. D. an impure substance because it is a mixture.
A
What did Ernest Rutherford's gold foil experiment demonstrate about atoms? A. Their positive charge is located in a small region that is called the nucleus. B. Their negative charge is located in small particles that are called electrons. C. Their nucleus makes up the majority of the volume of the atom. D. Their electrons are floating in a sea of positive charges.
A
What is the charge on an electron? A. -1 B. 0 C. +1 D. +2
A
Which best describes the effect of J. J. Thomson's discovery? A. The accepted model of the atom was changed. B. The accepted model of the atom was supported. C. Cathode ray tubes were no longer used in experiments due to poor results. D. Cathode ray tubes became the only instrument of use in the study of atoms.
A
Which conclusion could be made from Ernest Rutherford's gold foil experiment? A. Atoms are made up of mostly empty space. B. Atoms are mainly solid and block alpha particles. C. The volume of the nucleus is large compared to the rest of the atom. D. The mass of the nucleus is small compared to the rest of the atom.
A
Which event would be impossible to explain by using John Dalton's model of the atom? A. An iron atom emits particles when it is struck by light. B. An oxygen atom combines with two hydrogen atoms to form water. C. An acid reacts with a base to form salt and water. D. The atoms in sodium metal react with water.
A
Which particle is J. J. Thomson credited with discovering? A. electron B. neutron C. proton D. photon
A
Which sample is a pure substance? A. zinc oxide B. sugar dissolved in water C. pond water D. soil
A
Which scientist is credited with developing the first scientific atomic theory? A. John Dalton B. Joseph Proust C. Ernest Rutherford D. J. J. Thomson
A
Which statement about the electron-cloud model is true? A. It is the currently accepted atomic model. B. It can easily be replaced by existing models. C. It specifies the location and momentum of an electron. D. It does not explain the formation of emission lines.
A
Which statement best describes John Dalton's use of creativity in his work? A. He reinterpreted and retested Joseph Proust's results. B. He used a philosophy to conduct his experiment. C. He recorded his results as four parts of the atomic theory. D. He rejected Democritus's idea that matter was composed of atoms.
A
Which of these are examples of chemical changes? Check all that apply. A. burning a candle B. boiling alcohol C. frying an egg D. melting an ice cube E. making coffee
A C
Which of these discoveries contradict components of Dalton's atomic theory? Check all of the boxes that apply. A. Atoms contain smaller particles: protons, neutrons, and electrons. B. Atoms of a given element can bond to other atoms only in specific ways. C. Atoms of a given element can have different numbers of neutrons. D. Nuclear reactions can change an atom of one element into an atom of another element. E. All atoms of a given element have the same number of protons.
A C D
Who used scientific investigations to study atoms? Check all that apply. A. Dalton B. Democritus C. Rutherford D. Thomson
A C D
An atom of element Be has four protons, four electrons, and five neutrons. Which element below could be an isotope of this atom? A. sodium-10 B. beryllium-10 C. boron-9 D. carbon-9
B
Caffeine contains hydrogen, carbon, nitrogen, and oxygen atoms in a fixed ratio. A. mixture B. compound
B
Electrons are embedded in a mass of positively charged matter. A. electron cloud model B. plum pudding model C. Dalton model
B
How many electrons are in an atom of elemental sodium? A. equal to the number of neutrons B. equal to the number of protons C. equal to the number of protons and neutrons
B
Identify each of the atomic models described here. Atoms are indivisible spheres. A. plum pudding model B. Dalton model C. Bohr model
B
In an electrically neutral atom, the number of A. protons equals the number of neutrons. B. protons equals the number of electrons. C. neutrons equals the number of electrons.
B
Light shining on a strip of metal can dislodge electrons. Do you think this is more consistent with light being made up of waves or of particles? A. waves B. particles C. not sure
B
Soda is a mixture. The ingredients list for a can of soda is given below. (Carbonated water (water, carbon dioxide), high fructose corn syrup, sucrose, caramel color, phosphoric acid, natural flavors, caffeine. The ingredients of the soda are best described as A. mixtures B. compounds C. elements.
B
The diagram below shows some subatomic particles. (WHAT IS PROTONS/NEUTRONS MADE OF) What is the particle that is labeled with a question mark (?) in the diagram? A. beta particle B. quark C. isotope D. alpha particle
B
The mass number of Fe2+ is 56. How many neutrons are there in a single Fe2+ atom? A. 28 B. 30 C. 56 D. 58
B
Which activity is the best demonstration of J.J. Thomson's use of creativity in his work? A. ignoring observations in his experiment B. interpreting the results of his experiment C. physically assembling the apparatus for his experiment D. reading about Joseph Proust's work
B
Which cannot be chemically broken down into simpler substances? A. compound B. element C. solution D. mixture
B
Which element has an atomic number of 16? A. oxygen (O) B. sulfur (S) C. germanium (Ge)
B
Which is a substance that is made up of only one type of atom? A. compound B. element C. solution D. mixture
B
Who was the first person to suggest the existence of atoms? A. Dalton B. Democritus C. Proust D. Thomson
B
A number of substances and their chemical formulas are listed below. Check the ones that are compounds. A. neon (Ne) B. carbon monoxide (CO) C. glucose (C6H12O6) D. cobalt (Co) E. fluorine (F2)
B C
Check the statements that are a part of the Early Atomic Theory. Check all of the boxes that apply A. Scientists believe that the atom is made up of elements. B. Atoms combine in whole number ratios to form compounds. C. Atoms cannot be created or destroyed during a chemical reaction.
B C
Which of these statements is supported by the results of Thomson's experiment? Check all of the boxes that apply. A. Atoms are indivisible. B. Cathode rays are made up of negatively charged particles. C. Atoms contain negatively charged particles.
B C
Which of these are examples of physical changes? Check all that apply. A. burning wood B. freezing water C. cutting paper D. iron rusting E. mixing water and acetone
B C E
A change in which property of light will have no effect on whether or not the photoelectric effect occurs? A. frequency B. energy C. intensity D. wavelength
C
According to the Bohr model of an atom, what happens when an electron moves from the second energy level to the third energy level and then back to the second energy level? A. Energy is absorbed and then stored in the atom. B. Energy is released and then absorbed to form an absorption line. C. Energy is absorbed and then released to form an emission line. D. Energy is released from the atom, and the outer level is weakened.
C
An electron's position cannot be known precisely. Only its probability of being in a certain location can be known. A. Bohr model B. plum pudding model C. electron cloud model
C
How did the development of the earliest idea about atoms differ from the later work of scientists? A. It was based on sound evidence. B. There were explanations for the idea. C. It was based on the thoughts of an early philosopher. D. There were experiments conducted to support the idea.
C
How does the electron-cloud model describe electrons? A. The exact position of an electron can be known. B. An electron can be found at certain distances from the nucleus. C. An electron has a high probability of being in certain regions. D. Each electron follows a specific path around the nucleus.
C
Light is emitted by electrons when they drop from one energy level to a lower level. Which transition results in the emission of light with the greatest energy? A. level 2 to level 1 B. level 3 to level 2 C. level 4 to level 2
C
The table describes how some substances were formed. Substance Description P Formed by boiling pure water Q Formed by combining three hydrogen atoms to every nitrogen atom R Formed by adding 5 g of sugar to 1 L of water S Formed by compressing carbon under high pressure Based on the given descriptions, which substance is most likely a mixture? A. P B. Q C. R D. S
C
This flow chart shows the amount of energy that is emitted by each type of light. ultraviolet > blue light > yellow light > red light (maximum energy) (minimum energy) In an experiment, shining which type of light on a strip of metal would be least likely to produce the photoelectric effect? A. ultraviolet light B. dim blue light C. bright red light D. bright yellow light
C
What could J. J. Thomson conclude from his experiments? A. Atoms are mostly empty space. B. Most of the mass of the atom is concentrated in the center. C. Atoms must balance positive and negative particles. D. Atoms are indivisible.
C
What happens when the electron moves from the first energy level to the second energy level? A. Energy is absorbed, and an emission line is produced. B. Energy is released, and an emission line is produced. C. Energy is absorbed by the atom. D. Energy is lost from the atom.
C
Which statement describes a major drawback of the Bohr model that caused scientists to replace it? A. It worked only for helium and larger atoms. B. It did not identify the distance between an electron and the nucleus. C. It contradicted the Heisenberg uncertainty principle. D. It stated that spectral lines of atoms are similar.
C
Blue light waves have more energy than red light waves. Which of these situations most likely produces a photoelectric effect? You may assume that the same metal is used in each situation. Check all that apply. A. shining dim red light on a strip of metal B. shining bright red light on a strip of metal C. shining dim blue light on a strip of metal D. shining bright blue light on a strip of metal
C D
Carbon-12 and carbon-13 are isotopes of carbon. Which of the following statements is correct? A. They both have seven protons in the nucleus. B. They both have the same mass number. C. They both have seven neutrons in the nucleus. D. They both have the same atomic number.
D
The emission spectrum of hydrogen shows discrete, bright, colored lines. Which characteristic of the Bohr model is best supported by this observation? A. Energy is released when an electron moves to a higher energy level. B. Smaller atoms have fewer spectral lines than larger atoms. C. The energy of an electron increases with distance from the nucleus. D. Electrons cannot exist in locations other than in specific orbits.
D
What can a drop of liquid mercury be described as? A. a pure substance and a compound B. an impure substance that is reactive C. an impure substance that is unreactive D. a pure substance and an element
D
Which best describes a compound such as sodium chloride? A. a pure substance that can be separated into different elements by physical means B. a mixture of two common substances that can be separated by chemical means C. a mixture of two common elements that can be separated by physical means D. a pure substance that can be separated into different elements by chemical means
D
Which is a pure substance? A. soda B. gasoline C. salt water D. carbon dioxide
D
Which observation provided Albert Einstein the clue that he needed to explain the photoelectric effect? A. Light is made up of extremely small particles. B. Particles that are emitted from a strip of metal are electrons. C. Shining light on a metal strip produces emissions. D. Energy of electrons depends on light's frequency, not intensity.
D
Which statement best describes the relationship between the ingredients (in the soda)? A. They can be separated from each B. other only using chemical reactions. C. They are always present in exactly the same ratio in all sodas. D. They are not chemically bonded to each other.
D
Which statement best summarizes the importance of Ernest Rutherford's gold foil experiment? A. It proved that all of John Dalton's postulates were true. B. It verified J. J. Thomson's work on the atomic structure. C. It showed that an electron circles a nucleus in a fixed-energy orbit. D. It showed that a nucleus occupies a small part of the whole atom.
D
Which statement describes an electron? A. It has a positive charge and is located in the nucleus. B. It has a positive charge and is located in orbitals around the nucleus. C. It has a negative charge and is located in the nucleus. D. It has a negative charge and is located in orbitals around the nucleus.
D
Mark the statement as true or false. All of the proposed ideas by Dalton, Thomson, and Rutherford are still used in the Modern Theory of the Atom. true false
false
A hydrogen electron is elevated from level 1 to level 2. Another electron is elevated from level 2 to level 4. The transition requiring the greatest energy change is... A. level 1 to level 2 B. level 2 to level 4 C. both require the same amount of energy.
✔ level 2 to level 4
